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In the present work, we study the ovule, seed, and fruit development in six Bulbostylis species in order to characterize the genus in a comparative approach and to identify the characteristics that can be used in taxonomy and phylogeny. Flowers and fruits at different developmental stages were analyzed using LM and SEM after processing according to standard techniques. The species studied have the following: anatropous and bitegmic ovules, weak crassinucellar ovules, obturator of integumentary origin, monosporic embryo sac of the Polygonum type, nuclear endosperm, hypostase formation, seed coat formed by tanniferous endotegmen and exotesta, and Bulbostylis-type embryo. On the other hand, the pericarp development constitutes the main variation within Bulbostylis since the cells of the exocarp may or may not present starch grains, and their inner periclinal walls may be slightly or deeply concave depending on the degree of development of the mesocarp sclereids. In a taxonomic context, the results herein obtained are in conflict with studies which suggest infrageneric groupings based on fruit micromorphology, and also with the relationship among the Bulbostylis species based on molecular analysis. This work contributes to a better understanding of the reproductive anatomy and embryology in Bulbostylis, and reveals the first insights about the origin of multiple embryos in Cyperaceae. Given the frequent presence of polyembryony in Bulbostylis, and the poor mention of this condition in the family, this work highlights an aspect in the anatomy of Cyperaceae that must be re-explored.

Within Chloridoideae, subtribe Eleusininae comprises 237 species with little morphological diversity in its inflorescence structure. This diversity may be explained by an evolution from complex (pyramidal shaped and highly branched) to simpler (digitated and barely branched) morphologies. However, only mature specimens have been studied; the developmental analyses of the inflorescences are rare. We analyzed the inflorescence, spikelet, and flower development of 17 species belonging to subtribe Eleusininae using scanning electron microscopy. In the early stages of the transition to flowering of the studied species, the inflorescence meristem elongates initiating primary branches acropetally. The differentiation of these branches along the main axis is either basipetal or amphipetal. Though the initiation of secondary branches along primary branches may be acropetal or amphipetal, their differentiation follows an amphipetal direction. The florets within spikelets are initiated acropetally. We found abnormal orientation of stamens and gynoecium within florets of Leptochloa chloridiformis. The analysis of the ontogeny enriched the current knowledge of inflorescences of the subtribe. In addition, the developmental patterns revealed the existence of more than one developmental pattern that leads to similar mature inflorescence forms. The results serve for future efforts on postulating trends of developmental patterns along Poaceae. Fil: Muchut, Sebastián Elías. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pilatti, Vanesa. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Reutemann Arnolfo, Andrea Guadalupe. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

Inflorescence forms in grasses lead to a general assumption that their evolution is random. We reconstructed the ancestral inflorescence for Poaceae subtribe Eleusininae and outlined possible evolutionary pathways to test the hypotheses of (1) non-directionality in grass inflorescence evolution and (2) an evolutionary direction from complex to simpler inflorescence architectures in this lineage. By studying early stages of inflorescence and spikelet development, we investigated ontogenetic changes that may correlate with evolutionary pathways identified. The approach presented here indicates that the current diversity of inflorescences found in Eleusininae is probably a result of two distinct evolutionary pathways. The main path involves a multi-staged course with shortening of main axis internodes first, followed by a decrease in number of primary branches and florets per spikelet. We postulate that reduced elongation of the internodes may affect the apical and axillary meristems performance, which in turn promotes a decrease in the number of primary branches and floret per spikelet. Current diversity in inflorescences of Eleusininae may be a consequence of a reductive evolution. We found that the evolutionary directionality of inflorescences in Eleusininae may be associated with developmental events that affected inflorescence morphology at early stages.

Objectives: Mechanical impedance causes structural changes in roots. Nevertheless, little is known about the changes in soybean root systems grown under compacted soils (mechanical impedance). The aim of this work was to understand the morphological and topological-architectural changes occurred in plants root system of soybean grown under soil compaction. Methods/Analysis: Three experiments were carried out and three mechanical impedance levels were tested. Silt loam soil passed through a 2-mm-mesh sieve (Typic Argiudol Esperanza series) was used. Three soil compaction levels were determined: 1.1 g.cm-3, null mechanical resistance (NR); 1.3 g.cm-3, low mechanical resistance (LR); and 1.5 g.cm-3, corresponding to high mechanical resistance (HR). Three soil resistances were consequent determine: < 0.1 MPA, 0.5 MPa and 3.5 MPa, respectively. Morphological, geometrical and topological-architectural roots parameters were measured. Findings: Plants grown in HR conditions had a root system confined to the first centimeters of the ground and showed shorter total root length, less number of lateral roots, higher diameter and low specific length. Growth form of root systems was sensitive to soil mechanical impedance even at resistance levels lower than 1 MPa. As soil impedance increases, lateral root growth occurs via the principal root rather than via the secondary roots and there were higher numbers of lateral roots on the principal root in the area from the proximal zone to the stem base. Novelty/Improvement: The main differences among NR, LR and HR plants were due to changes in the characteristics of the root system rather than in the shoot system, particularly in the root growth zone. As a conclusion, the present research demonstrates that there are morphological parameters that can be used to determine if crops have been exposed to soil compaction. Keywords: Architectural Parameters, Compacted Soil, Glycine Max, Morphological Parameters, Root Growth, Root System, Topological Parameters

Introducción y objetivos: Commelina erecta y Eutsachys retusa son malezas perennes tolerantes a glifosato. El propósito de este estudio fue caracterizar el banco de yemas de ambas especies y evaluar su respuesta a la aplicación de glifosato. M&M: Se analizaron yemas de 120 ejes reproductivos de C. erecta y 60 ejes reproductivos de E. retusa, a los 30 y 60 días después de la aplicación del herbicida. Las dosis empleadas en C. erecta fueron 0 (control), 1.200 y 2.400 g a.i. ha-1 y en E. retusa fueron 0 (control), 480 y 1200 g a.i. ha-1. Resultados: Ambas especies presentaron yemas activas en aproximadamente el 50% de los nudos, incluso después de la aplicación del herbicida. Ambas malezas alteraron la dinámica del banco de yemas y su patrón de crecimiento post-aplicación del herbicida. Es decir, la activación de yemas originalmente inhibidas permitió que ambas malezas rebroten y sobrevivan, alterando su arquitectura. Conclusiones: El banco de yemas juega un papel importante en la tolerancia a Glifosato en ambas malezas. En ambas especies, la capacidad de rebrote fue similar en cualquiera de las dosis de glifosato aplicadas; por lo tanto, una estrategia de control que aumente la dosis de herbicida no sería una alternativa exitosa para el manejo de estas malezas. La interrupción del almacenamiento de reservas en el sistema de rizomas y la reducción de la cantidad de yemas, serían factores claves para un manejo efectivo a largo plazo de estas y otras malezas perennes, en un sistema de labranza cero. Background and aims: Commelina erecta and Eutsachys retusa are two perennial weeds, which show high resprouting after glyphosate application. This behavior represents a serious problem for weed management. The purpose of this study was to characterize the bud bank of both species and to assess their response to glyphosate application. M&M: We analyzed 120 reproductive shoots of C. erecta, and 60 reproductive shoots of E. retusa, at 30- and 60-days post- herbicide application. The doses applied to C. erecta were 0 (control), 1.200 and 2.400 g a.i. ha-1, and to E. retusa were 0 (control), 480 and 1200 g a.i. ha-1. Results: We found that both species presented active buds in approximately 50% of their nodes, even after herbicide application. Bud bank dynamics changed in both weeds after herbicide application, and therefore their growth pattern. The activation of originally inhibited buds allowed weeds to regrow and survive after glyphosate application altering their architecture. Conclusions: The bud bank plays an important role in glyphosate tolerance in both weeds. The resprouting capacity in both species was similar for any dose of glyphosate applied. Therefore, an alternative control strategy based on the increase of the dose of herbicide would not be a successful alternative for the management of these weeds. The interruption of the storage of reserves in the rhizome system and the reduction of the number of buds would be key to effective long-term management of these and other perennial weeds in no tillage cropping system. Fil: Panigo, Elisa. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Dellaferrera, Ignacio Miguel. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Alesso, Carlos Agustín. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Perreta, Mariel Gladis. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

Background: Small RNAs regulate a wide variety of processes in plants, from organ development to both biotic and abiotic stress response. Being master regulators in genetic networks, their biogenesis and action is a fundamental aspect to characterize in order to understand plant growth and development. Three main gene families are critical components of RNA silencing: DICER-LIKE (DCL), ARGONAUTE (AGO) and RNA-DEPENDENT RNA POLYMERASE (RDR). Even though they have been characterized in other plant species, there is no information about these gene families in Citrus sinensis, one of the most important fruit species from both economical and nutritional reasons. While small RNAs have been implicated in the regulation of multiple aspects of plant growth and development, their role in the abscission process has not been characterized yet. Results: Using genome-wide analysis and a phylogenetic approach, we identified a total of 13 AGO, 5 DCL and 7 RDR genes. We characterized their expression patterns in root, leaf, flesh, peel and embryo samples using RNA-seq data. Moreover, we studied their role in fruit abscission through gene expression analysis in fruit rind compared to abscission zone from samples obtained by laser capture microdissection. Interestingly, we determined that the expression of several RNA silencing factors are down-regulated in fruit abscission zone, being particularly represented gene components of the RNA-dependent DNA Methylation pathway, indicating that repression of this process is necessary for fruit abscission to take place in Citrus sinensis. Conclusions: The members of these 3 families present characteristic conserved domains and distinct expression patterns. We provide a detailed analysis of the members of these families and improved the annotation of some of these genes based on RNA-seq data. Our data suggests that the RNA-dependent DNA Methylation pathway is involved in the important fruit abscission process in C. sinensis. Fil: Sabbione, Agustín Andrés. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Daurelio, Lucas Damian. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Veggeti, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Talón, Manuel. Institut Valencià Dinvestigacions Agràries; España Fil: Tadeo, Francisco. Institut Valencià Dinvestigacions Agràries; España Fil: Dotto, Marcela Claudia. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

Inflorescence morphology in Poaceae subtribes Hilariinae, Monanthochloinae, Boutelouinae, Scleropogoninae and Muhlenbergiinae (Cynodonteae, Chloridoideae) has been revisited recently, but inflorescence development remains largely unexplored. The aim of this study is to contribute additional information on the development of inflorescences in Cynodonteae by generating data on Distichlis, Bouteloua, Munroa, Erioneuron and Muhlenbergia and to compare them with results for other grasses. Using scanning electron microscopy images, we identified common developmental patterns among grasses and described developmental novelties for Bouteloua, Distichlis and Muhlenbergia. Novel developmental features are: the amphipetal initiation of second-order branches along the inflorescence of B. curtipendula, the elongation of the internodes of the inflorescence branches before floral development in M. asperifolius and ‘Type II’ unisexual flowers in D. acerosa. Variable traits among studied species are: inflorescence symmetry, direction of branch and spikelet initiation and differentiation, number of developing stamens, glume developmental patterns and timing of the arrest of gynoecium development during the formation of unisexual flowers. Our results allow us to postulate that a delicate balance of phytohormones may direct early development of grass inflorescence branching system by controlling direction of first-order branch differentiation. The approach used here provides a link between definitive structures and the underlying genetics. EEA Rafaela Fil: Pilatti, Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pilatti, Vanesa. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafalea; Argentina Fil: Pilatti, Vanesa. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Muchut, Sebastián Elías. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Muchut, Sebastián Elías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Uberti Manassero, Nora Graciela. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Uberti Manassero, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Reinheimer, Renata. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

This work presents an analysis of the homogenization and truncation processes in Cyperaceae inflorescences. The truncation process is rare in Cyperaceae. There may be homogenized inflorescences but in general these inflorescences present a terminal spikelet. In the few studied cases of truncated inflorescences in Cyperaceae the truncation process may affect the terminal spikelet, only on the main axis and on the long primary branches (species of Cariceae, species of Lipocarpha and Ascolepis), or it may also affect the short branches on the main axis (some species of Kobresia; Cyperus giganteus, C. papyrus and C. prolifer) and on the primary long branches (Cyperus giganteus, C. papyrus and C. prolifer). The homogenized inflorescences can be disjunct or not disjunct. The disjunct homogenized inflorescences have a distal portion of short branches and a proximal portion of long branches, which lead in turn as short branches subunits. Meanhile non-disjunct homogenized inflorescences have only short or long branches, all with the same branching degree. Fil: Bender, Adrian Gabriel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Ramos, Julio Cesar. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tivano, J. C.. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

This work provides an analysis of the spikelet structure in Cypereae, and their taxonomic and phylogenetic implications. The main variations in the Cypereae spikelets are seem in: number and phyllotaxis of the glumes, presence/absence of empty glumes, glume morphology, rachilla internode length, prophyll development, flower structure and structure of the dispersal unit. Consistently with the latest molecular phylogenies proposed for Cypereae, our results support the division of this tribe into two groups with spikelet characters more or less typical: the Cyperus and the Ficinia clades. Within the Cyperus clade, the existence of spikelets with convergent characters among the different taxa supports the inclusion of all this clade taxa within one wide genus Cyperus, just as the current phylogenetic hypotheses proposed for the group. Fil: Uberti Manassero, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Reutemann Arnolfo, Andrea Guadalupe. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Ardissone, Rodrigo. Universidade Federal do Rio Grande do Sul; Brasil Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

The species of the Cynodonteae tribe show great morphological diversity in their reproductive structures. Previous studies where inflorescences were comparatively analysed in the context of phylogeny have shown that although grass inflorescences seem to be excessively variable, there are certain aspects of inflorescences that store relevant information on the evolution and systematics in Poaceae. We have analysed and compared the inflorescence structures of species belonging to the Hilariinae, Monanthochloinae, Scleropogoninae, and Muhlenbergiinae subtribes. Considering the most relevant morphological characters, the most recurrent types of inflorescences in the lineage were determined by means of a principal coordinates analysis. To understand the evolution of inflorescence morphology, ancestral reconstructions of inflorescence characters were performed using the Bayesian inference method. The results obtained demonstrate that the processes of homogenization and truncation might account for the diversity observed in adult inflorescences. Five different types of inflorescences were identified out of 36 theoretical possibilities. Amongst these, inflorescence type 1 (panicle of spikelets, with a terminal spikelet, non-homogenized, and bearing third- or higher-order branches) was found to be the most frequent in the studied group. Ancestral reconstructions of morphological characters allowed us to suggest that the ancestor of the group might have had an inflorescence with the form of a raceme of spikelets, non-truncated and bearing first-order branches. More complex inflorescences bearing no terminal spikelets and having branches of higher order might have diverged this lineage. Fil: Pilatti, Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Muchut, Sebastián Elías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Uberti Manassero, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

This review is intended: (1) to interpret and characterize morphological variations observed in the structure of the enrichment axes, located below the terminal inflorescence in Poaceae; and (2) to study the relationship between the intensity of development of such axes and the size of terminal inflorescence. An important reduction in the development of the terminal inflorescence is generally accompanied by a significant development of enrichment axes. It is necessary to adequately characterize these enrichment axes, differentiating them from the terminal inflorescence. Since the intensive development of enrichment axes in synflorescences of many grass genera has caused misinterpretations of the inflorescence structure, to include them as parts of the terminal inflorescence. Fil: Muchut, Sebastián Elías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Pilatti, Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina Fil: Uberti Manassero, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Perreta, Mariel Gladis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina

Previous molecular phylogenetic analyses of the family Cyperaceae based on rbcL sequences showed Bulbostylis as paraphyletic, with B. atrosanguinea and B. hispidula forming a clade with Nemum spadiceum. On the contrary, phylogenetic analyses of the tribe Abildgaardieae based on nuclear (ITS ribosomal region) and plastid sequences (trnL-F region) showed Bulbostylis as monophyletic, although they only incorporated four species of Bulbostylis and none of Nemum. In this work, we presented a phylogenetic hypothesis of Bulbostylis based on a comprehensive sampling, including species from different continents for the first time. New sequences of Abildgaardia, Crosslandia, Fimbristylis, and Nemum were included to test the monophyly of Bulbostylis. In total, 84 sequences of both ITS and trnL regions were generated. Analyses were performed using Bayesian inference, maximum likelihood, and parsimony. Ancestral state reconstruction was performed using ML, MCMC, and parsimony methods. In all analyses, Bulbostylis resulted paraphyletic as Nemum atracuminatum is nested within it. Most American species of Bulbostylis grouped together, but relationships amongst them appeared poorly resolved. Ancestral state reconstructions of native distribution suggest an African ancestor of Bulbostylis, with at least three introduction independent events of the species in America. Morphological diagnostic characters such as the ‘style base permanence or detachment from the ripe achene’, and the ‘micromorphological patterns of the achene surface’ are homoplastic in this phylogenetic context, and therefore unsuitable to propose infrageneric groupings within the Bulbostylis. Fil: Reutemann Arnolfo, Andrea Guadalupe. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Ardissone, Rodrigo E.. Universidade Federal do Rio Grande do Sul; Brasil Fil: Lopez, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Muchut, Sebastián Elías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral; Argentina Fil: Boldrini, Ilsi. Universidade Federal do Rio Grande do Sul; Brasil Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Giussani, Liliana Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

This paper aims to interpret and characterize the inflorescence of Koyamaeae tribe from the typological point of view in order to establish homologies and promote comparative studies and the use of inflorescence characters in future phylogenetic studies. The Koyamaeae tribe is comprised of one monotypic Koyamaea W. Thomas &Davidse genus, with K. neblinensisW. Thomas&Davidse. Koyamaea neblinensis has a synflorescence type II and/or type III made up by a many-noded culm, covered by sheaths, usually unbranched (synflorescence type II), but occasionallywith 1?2 branches from the upper half (synflorescence type III). The inflorescence of Koyamaea shows a main axis leading to a terminal spikelet (main florescence) and a primary branch (primary paraclade) arising from the axillary bud of the single involucral bract. Accordingly, the inflorescence is composed of the main florescence and a highly reduced paracladial zone. This paracladial zone is reduced to one node where a single primary paraclade is inserted. This primary paraclade consists of a short hypopodium, a prophyll, an epipodium and a terminal spikelet (or coflorescence). The axillary bud of the prophyll develops a secondary branch (secondary Paraclade) with a similar structure to that of the primary paraclade. All subsequent higher-order branches also arise in the axils of prophylls. Inflorescence characters of this tribe are discussed in relation to related tribes Sclerieae, Bisboeckelereae, Cryptangieae and Trilepideae (sensu Goetghebeur, 1998). Fil: Dellaferrera, Ignacio Miguel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

Inflorescences in Cyperaceae are a source of characters with significant systematic value; however, the structure and primary homologies pose a challenge to their interpretation. The relationships among members of Abildgaardieae are not clear due to the absence of a phylogeny with strong support, comprising a representative number of species. Establishing correct primary homologies of inflorescences within Abildgaardieae might help to clarify the relationships among its members, as well as to find synapomorphies for the most important clades. Variations in the mature inflorescences within Abildgaardieae have been related to their ?shape? and ?structure?, and preliminary phylogenetic studies in species of Bulbostylis have shown that inflorescence structure traits are phylogenetically informative, but this is not true for the mere shape. While similar structures in the adult inflorescences of the members of different clades within Abildgaardieae might be considered homologous, it must be ascertained whether such similar structures share the same developmental process or have different developmental patterns. By studying the development of inflorescences in selected species of Abildgaardieae using SEM, we were able to show that inflorescences with homologous structures share a similar developmental process and, therefore, the adult structure of inflorescences may be relied on for establishing correct primary morphological homologies in this plant group. Most structural variations of inflorescences in Abildgaardieae depend on the degree of development of processes shared by the studied species. While phyllotaxis in the main axis of Cyperus may be modified during inflorescence development after primordial inception, variations in the phyllotactic patterns of leaves on vegetative shoots (=nomophylls) and of leaves on fertile shoots (=bracts or hypsophylls) within Abildgaardieae, might establish deeper differences in inflorescence structure, since they depend on changes in the shape of the apical meristem. Fil: Reutemann, Andrea G.. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Catedra de Morfologia Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Catedra de Morfologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pozner, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentina

Jouvea is a dioecious genus of grasses with two species. Molecular phylogenetic analyses place it in tribe Cynodonteae, closely related to subtribes Hilariinae and Scleropogoninae, and the genera Allolepis and Sohnsia. The staminate inflorescence in Jouvea is an ordinary grass spike of spikelets, but the pistillate inflorescence is represented by a single spikelet which lacks glumes, has a thick and cylindrical rachilla, lemmas forming a tube that enclose the palea and pistil, stigmas protruding from an apical pore of this tube, and does not have lodicules. Within Cynodonteae, inflorescences reduced to a single spikelet also occur in subtribe Monanthochloinae, in which the small number of flowers of the terminal inflorescence is compensated by an increase in the number of lateral floriferous shoots. We here describe the floriferous shoot system (synflorescence) of Jouvea and compare it to other cynodonteae grasses with reduced inflorescences. Jouvea species display a high number of lateral shoots (trophotagma enrichment axes) growing from the medial and distal zones of the synflorescences. These shoots have prophyllar origins and form clusters of lateral inflorescences. The elevated number of trophotagma enrichment axes of Jouvea may be associated with the extreme reduction in the pistillate terminal inflorescence. In addition, the increase in number of spikelets by the development of prophyllar branches is a unique strategy within tribe Cynodonteae. Fil: Muchut, Sebastián Elías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Reutemann Arnolfo, Andrea Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Uberti Manassero, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina

Cytosolic glyceraldehyde-3-phosphate dehydrogenase (NAD-GAPDH) is involved in a critical energetic step of glycolysis and also has many important functions besides its enzymatic activity. The recombinant wheat NAD-GAPDH was phosphorylated in vitro at Ser205 by a SNF1-Related protein kinase 1 (SnRK1) from wheat heterotrophic (but not from photosynthetic) tissues. The S205D mutant enzyme (mimicking the phosphorylated form) exhibited a significant decrease in activity but similar affinity toward substrates. Immunodetection and activity assays showed that NAD-GAPDH is phosphorylated in vivo, the enzyme depicting different activity, abundance and phosphorylation profiles during development of seeds that mainly accumulate starch (wheat) or lipids (castor oil seed). NAD-GAPDH activity gradually increases along wheat seed development, but protein levels and phosphorylation status exhibited slight changes. Conversely, in castor oil seed, the activity slightly increased and total protein levels do not significantly change in the first half of seed development but both abruptly decreased in the second part of development, when triacylglycerol synthesis and storage begin. Interestingly, phosphoNAD-GAPDH levels reached a maximum when the seed switch their metabolism to mainly support synthesis and accumulation of carbon reserves. After this point the castor oil seed NAD-GAPDH protein levels and activity highly decreased, and the protein stability assays showed that the protein would be degraded by the proteasome. The results presented herein suggest that phosphorylation of NAD-GAPDH during seed development would have impact on the partitioning of triose-phosphate between different metabolic pathways and cell compartments to support the specific carbon, energy and reducing equivalent demands during synthesis of storage products. Fil: Piattoni, Claudia Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Ferrero, Danisa María Luján. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Dellaferrera, Ignacio Miguel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Iglesias, Alberto Alvaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

We studied the inflorescences of 112 members of tribe Chloridoideae subtribe Eleusininae from a morphological and evolutionary perspective to identify the most frequent types and to explore the evolutionary history of selected inflorescence associated characters. Six characters were scored on adult specimens and a principal coordinate analysis was conducted to identify inflorescence types. To investigate the evolution of inflorescences we regenerated the phylogeny of the subtribe and performed ancestral character state reconstructions using parsimony methodology. All species have panicles of spikelets with pyramidal, digitate or single-branched appearances. The number of primary branches varies widely among species, although some species have a single primary branch. The lack of terminal spikelet (truncation) and the similarity among primary branches of the inflorescence (homogenization) characterize the majority of the subtribe. In Eleusininae, the spikelet may be uni-, two- or multi-flowered. We found 13 inflorescence types in the group among 72 putative inflorescence forms. About 75% of the species can be divided to five different inflorescence types. Ancestral state reconstruction suggests an evolutionary direction towards simpler inflorescences with spikelets that contain 1-2 florets. Fil: Muchut, Sebastián Elías. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Ministerio de Ciencia. Tecnología e Innovación Productiva. Agencia Nacional de Promoción Cientifíca y Tecnológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pilatti, Vanesa. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Uberti Manassero, Nora Graciela. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Reinheimer, Renata. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

Formas de crecimiento de Parietaria debilis(Urticaceae) y Veronicapersica (Plantaginaceae).Este trabajo analiza las formas de crecimiento en V. persicay P. debilis, para identificar su desarrollo estructural. El sistema de ramificación, su variación temporal y espacial, características estructurales y de desarrollo, así como la dirección de crecimiento y s ecuencia foliar fueron estudiados en plantas cultivadas a p artir de semillas, en cámaras de crecimiento y en pl antas coleccionadas a campo. En ambas especies tanto el eje principal como las ramas basales se comportan de manera similar, constituyendo estructuras equivalentes. A lo largo del eje principal y de los paracladios basales de V. persica, se observó una zona de producción de ramas largas, una zona de inhibición, con hojas en filotaxis opuesta, y una zona terminal que porta las flores de filotaxis alterna. Parietaria debilis no presentó de zona de inhibición y muestró un tipo continuo de ramificación. Presentó un eje principal y ramas largas de hasta sexto orden, sobre estos ejes se desarrollan ramas cortas que portan a su vez las ramas florales. Al ser anuales todas las estructuras producidas durante el ciclo crecimiento constituyen una sinflorescencia. La forma de crecimiento de estas dos especies, tiene implicancias importantes en su comportamiento como malezas de cultivos, debido a su alta capacidad de producir estructuras florales en forma rápida y continua asegurando ampliamente su producción de semillas.

A group of sunflower lines that exhibit a range of leaf Na+ concentrations under high salinity was used to explore whether the responses to the osmotic and ionic components of salinity can be distinguished in leaf expansion kinetics analysis. It was expected that at the initial stages of the salt treatment, leaf expansion kinetics changes would be dominated by responses to the osmotic component of salinity, and that later on, ion inclusion would impose further kinetics changes. It was also expected that differential leaf Na+ accumulation would be reflected in specific changes in cell division and expansion rates. Plants of four sunflower lines were gradually treated with a relatively high (130 mm NaCl) salt treatment. Leaf expansion kinetics curves were compared in leaves that were formed before, during and after the initiation of the salt treatment. Leaf areas were smaller in salt-treated plants, but the analysis of growth curves did not reveal differences that could be attributed to differential Na+ accumulation, since similar changes in leaf expansion kinetics were observed in lines with different magnitudes of salt accumulation. Nevertheless, in a high leaf Na+-including line, cell divisions were affected earlier, resulting in leaves with proportionally fewer cells than in a Na+-excluding line. A distinct change in leaf epidermal pavement shape caused by salinity is reported for the first time. Mature pavement cells in leaves of control plants exhibited typical lobed, jigsaw-puzzle shape, whereas in treated plants, they tended to retain closer-to-circular shapes and a lower number of lobes. Fil: Céccoli, Gabriel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Bustos, D.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina Fil: Ortega, Leandro Ismael. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Senn, María Eugenia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Taleisnik, Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Mesquite (Prosopis alba Grisebach), an important species in arid and semiarid regions, is currently commercially propagated by seeds and so there is great interest in developing techniques for species propagation, domestication and improvement. Cloning through mini-cuttings is a new and promising technique for the production of clonal seedlings of forest species. The main objective of this work was to evaluate vegetative propagation using the mini-cutting technique and indolebutyric acid (IBA) at different concentrations (0, 3,000, 4,500, 6,000 and 7,500 mg L−1) on rooting of P. alba clones. Rooting was achieved in 98–100 % of the mini-cuttings at all concentrations tested. Increasing IBA concentration resulted in an increase in the number of leaves and leaflets, as well as in fresh matter weight and number and length of roots of clone seedlings, until an optimum point (between 3480 and 4800 mg L−1) was reached. Plants were also vegetatively propagated in the field via conventional clonal garden cuttings under the same rooting conditions to compare the efficiency of the two propagation techniques. Mini-cuttings showed higher rooting and survival percentages than cuttings. A correlation analysis conducted between characteristics of stock plants (height, diameter, number of shoots) and shoots (height, diameter) showed a positive correlation between rooting and height of shoots with total root length, leaflet number, and height of clonal seedlings. We propose the mini-cutting technique as a tool for P. alba cloning.

Ascolepis and Lipocarpha, Cyperaceae, have highly reduced reproductive structures and hypogynous scales that are controversially appreciated. Because of this, flowers and spikelets and, thus, inflorescences have been interpreted in different ways, which, in turn, has led to placing the two genera in different tribes. Some authors interpret spikelets in Ascolepis and Lipocarpha as many-flowered and the so-called hypogynous scales as homologous to the lateral scales of Hypolytrum, or consider these scales comparable to a Scirpus bristle. However, many other authors consider spikelets in Lipocarpha and Ascolepis to be a result of a reductional process from a many-flowered cyperoid spikelet to a single-flowered spikelet, where the adaxial and abaxial hypogynous scales may be seen as the respective prophyll and glume of the reduced spikelets. The latest molecular phylogenies of Cyperaceae show both genera nested in the Cyperus clade, forming, in turn, a clade together with the rest of the Cypereae genera having single-flowered spikelets and hypogynous scales. Alternatively, based on this, the scales of uncertain homology that accompany the Ascolepis and Lipocarpha flower might be seen as special reproductive formations, representing a synapomorphy of such clade, instead of relicts of an ancestor with many-flowered spikelets. In view of this, freshly collected inflorescences of Lipocarpha humboldtiana Nees and Ascolepis brasiliensis (Kunth)Benth. ex C. B. Clarke were studied using light and scanning electron microscopy, with the aim of elucidating the nature of the controversially interpreted reproductive structures of these species from a development perspective. Results show that the ?hypogynous scales? simply represent vestigial structures derived from the reduction of typical cyperoid spikelets, rather than a perianth part or specialized formations emerging as evolutionary novelties. Two scales are typically generated in both species, one being abaxial and the other adaxial, homologous to a glume and a prophyll, respectively, which contrasts with the eprophyllate condition so far attributed to Ascolepis. In both cases, the inflorescence is a spike of reduced spikelets, and the floral development in L. humboldtiana and in A. brasiliensis follows the general ontogenetic pattern observed in Cyperoideae. These characteristics support the inclusion of both genera in the Cypereae tribe. Fil: Reutemann Arnolfo, Andrea Guadalupe. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Catedra de Morfologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina Fil: Pilatti, Vanesa. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Catedra de Morfologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina Fil: Guarise, Nicolas Javier. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Catedra de Morfologia Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Catedra de Morfologia Vegetal; Argentina

Sunflower (Helianthus annuus L.) has been rated as moderately salt-resistant, and variability for salt resistance has been detected within this crop. However, variability in salt-resistance mechanisms has not been assessed. Osmotic tolerance, the relation of salt resistance with whole-plant Na+ and K+ distribution and tissue Na+ tolerance were investigated in several sunflower inbred lines. Plants were grown under controlled conditions, in pots with sand and perlite irrigated with salinized (NaCl, –0.65 MPa) nutrient solution. Osmotic tolerance was assessed from the initial effects of the salt treatment on plant elongation in eleven sunflower lines. Long-term salinity responses were evaluated in four of those lines, by assessing whole-plant growth. A principal components analysis (PCA) was run on relative-to-control growth data, and this information was used to establish a relative resistance ranking, which indicated lines HAR2 > HAR1 > HA64 > HAR5. Osmotic tolerance was observed in HA64 and HAR2. The lines showed different degrees of Na+ accumulation, it was very low in some of them, but relative salt resistance was not associated to this trait. Tissue Na+ tolerance was deduced by comparing the percentage of dead leaves as a function of leaf blade Na+ accumulation, and it was higher in HAR1 than in the rest. These results indicate that variability for salt-resistance mechanisms exists in sunflower. Osmotic tolerance and tissue Na+ tolerance were detected in different lines, highlighting that such variability may be exploited for increasing salt resistance in this crop.

Inflorescence forms can be described by different combinatorial patterns of meristem fates (indeterminate versus determinate). In theory, the model predicts that any combination is possible. Whether this is true for grasses is unknown. In this paper, the subfamily Panicoideae s.s. (panicoid grasses) was chosen as the model group to investigate this aspect of grass inflorescence evolution. We have studied the inflorescence morphology of 201 species to complement information available in the literature. We have identified the most recurrent inflorescence types and character states among panicoids. Using multivariate approaches, we have indentified correlations among different inflorescence character states. By phylogenetic reconstruction methods we have inferred the patterns of panicoid inflorescence evolution. Our results demonstrate that not all theoretical combinatorial patterns of variation are found in panicoids. The fact that each panicoid lineage has a unique pattern of inflorescence evolution adds an evolutionary component to combinatorial model. Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentina. Universidad Nacional del Litoral; Argentina Fil: Amsler, Alicia. Universidad Nacional del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral; Argentina

In Cyperaceae, leaf anatomical characters, in particular the presence of a hypodermis or of a multiple epidermis, have contributed in taxonomic and phylogenetic studies. In this family, the leaf epidermis is often described as uniseriate, and the cells of the subepidermal layers having no chloroplasts are treated as hypodermis. Both tissues have a different ontogenetic origin and hence are not homologous. The aim of the present work was to verify the origin of the subepidermal layers in eight species belonging to Cyperoideae. All species studied presented multiple epidermal layers that were confirmed by leaf ontogeny. In Fimbristylis complanata, F. dichotoma, Pycreus flavescens and P. polystachyos the mature leaves present multiple epidermal layers with cells of the distinct layers similar in shape and size; in the other species studied these cells are different. Especially in the latter case, a multiple epidermis is easily interpreted erroneously as a hypodermis, possibly leading to erroneous evolutionary conclusions. Making correctly distinction between a hypodermis and a multiple epidermis, and hence in case of doubt investigating the origin of the questioned tissue, is compulsory in order to use both characters in a phylogenetic context. Though in the past often called ‘hypodermis’, our leaf ontogenetical observations show that in all species studied, the subepidermical layers constitute a multiple epidermis, originating from the protodermis. Fil: Martins, Shirley. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil Fil: Pilatti, Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Scatena, Vera Lucia. Instituto de Biociencias; Brasil

This work presents the basics for interpreting the adult inflorescence structure in Cyperaceae. It provides an analysis of the variations of the synflorescence and inflorescence structure in the family. Three types of synflorescence may be recognized in this family: a synflorescence with a foliate stem, a terminal inflorescence and a variable number of lateral inflorescences; a synflorescence with a foliate stem and only the terminal inflorescence; and a synflorescence with a scape and a terminal inflorescence. Variations in the structure and form of the inflorescences are related to variations in inflorescence branching, inflorescence homogenization degree, presence or absence of the distal part of the inflorescence, phyllotaxis, inflorescence position, types of bracts and leaves subtending branches, elongation of inflorescence internodes and spikelet structure. These variations are correlated with some of the developmental processes that give origin to the inflorescence.

The Abildgaardieae tribe within the family Cyperaceae comprises six or seven genera, among which Abildgaardia , Bulbostylis and Fimbristylis pose a challenge regarding their morphological delimitation. Molecular phylogenetic analyses including species of Abildgaardieae are rare, but in most of those studies, Abildgaardia and Fimbristylis appear as more closely related to each other than to the Bulbostylis genus. Duration of the style base has been one of the most widely used characters for delimiting these three genera. The style base is a persistent structure in most species of Bulbostylis and deciduous in Abildgaardia and Fimbristylis. The reasons why the style base may persist or fall off have been scarcely discussed. The assumption that abscission layers are present in the style base of all three genera and the fact that tracheids have been observed in the style base of Bulbostylis suggest that this structure might have histological complexity. In view of this, a complete ontogenetic and anatomical study of the gynoecium has been carried out for all these three genera. It turned out that the style base is histologically simple in Abildgaardia , Bulbostylis and Fimbristylis and shows similar structure and development in all three genera. The fact that the style base has a shorter duration in Abildgaardia and Fimbristylis than in Bulbostylis might be related to the lower number of sclerotised cells that make up such structures in the mature fruit of the former two genera. Abscission of the style and style base may be the result of much simpler reasons than the differentiation of an abscission layer, resulting merely from mechanical shear force effects. Differences among genera have been observed in the shape of the style base and the development of the style. The histological simplicity of the style base is consistent with the homoplastic appearance of this structure in genera that are not closely related (e.g. Rhynchospora ). Because of this, while the presence of the thickened style base seems to be a synapomorphy in species of Abildgaardieae, its persistence on or detachment from the fruit might have emerged repeatedly during this clade evolution and might not be a suitable character for genera delimitation.

We investigated the inflorescence structure of Rhynchospora following the methodology and terminology of Troll's school, with the objective of providing a characterization of the inflorescence suitable to evaluate the processes responsible for the diversity observed. Homogenization of inflorescence structures may occur fully or partially. In the first case, all branches of the inflorescence are homogeneous, while in the later, distal and proximal parts of the inflorescence bear homogeneous branches, but in the middle portions of the inflorescence non-homogeneous branches exist. Other characters leading to different forms of inflorescences are branching degree, internode elongation along the main axis of the synflorescence, degree of epipodium elongation of distal paraclades, development of bract and prophyll, and development of prophyllar paraclades. We identified three main types of inflorescences: (1) partially homogeneous paniculodia, (2) partially homogeneous capitate heads, and (3) a fully homogeneous capitate head. Within the first type, four subtypes were also recognized. Finally, we discuss how these processes can operate to produce the variation of the inflorescence shape. © 2011 Elsevier GmbH. Fil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

The function of the class I TCP transcription factor TCP15 from Arabidopsis thaliana has been studied through the analysis of plants that express a fusion of this protein to the EAR repressor domain. Constitutive expression of TCP15-EAR produces growth arrest at the seedling stage, before leaf emergence. Expression of the repressor fusion from the AtTCP15 promoter produces small plants with leaves whose margins progressively curve upwards, starting from the basal part of the lamina. Leaves contain smaller and less differentiated cells, both on the adaxial and abaxial sides. The abaxial domain is relatively enlarged, with disorganized cells separated by empty spaces. TCP15-EAR also affects the growth of leaf petioles, flower pedicels, and anther filaments. Flowers show reduced elongation of the three outer whorls and altered gynoecia with irregular carpel surfaces and enlarged repla. Ectopic stigma-like structures develop from medial and basal parts of the replum. TCP15-EAR produces an increase in expression of the boundary-specific genes LOB, CUC1, and CUC2. Changes in CUC1 and CUC2 expression can be explained by the existence of lower levels of miR164 in leaves and the repression of IAA3/SHY2 and the SAUR-like gene At1g29460 in leaves and flowers. TCP15 binds to the promoter regions of IAA3/SHY2 and At1g29460, suggesting that these genes may be direct targets of the transcription factor. The results indicate that TCP15 regulates the expression of boundary-specific genes through a pathway that affects auxin homeostasis and partially overlaps with the one modulated by class II CIN-like TCP proteins.

The structure of the synflorescence and the flowering units in Amaranthaceae are characterized. The synflorescence is polytelic. In the flowering unit we recognize the main florescence and the enrichment zone. The florescences may consist of: (1) Fully developed partial florescences bearing three or more flowers; (2) Partial florescences reduced to one or a few fertile flowers having prophylls with more or less modified axillary productions; or (3) No partial florescences but solitary flowers having prophylls with no axillary productions. We described the flowering unit in species with florescences bearing a solitary flower and the flowering unit in species with florescences bearing partial florescences. Hypothesized developmental processes are described, with a view to finding relationships among different models characterized in the family as well as defining characters for cladistic studies, which may be useful to depict all the variations observed. Fil: Acosta, Juan Manuel. Universidad Nacional del Litoral; Argentina Fil: Perreta, Mariel Gladis. Universidad Nacional del Litoral; Argentina Fil: Amsler, Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral; Argentina

This work presents the basics for interpreting the adult inflorescence structure in grasses. It provides an analysis of the variations in the grass inflorescence structure and their correlation with some of the developmental processes that give origin to it. © 2009 The New York Botanical Garden. Fil: Perreta, Mariel Gladis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Ramos, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

The objective of this review work is to characterize the enrichment axes in Poaceae, especially integrating into that analysis of those species with basal or subterranean cleistogamous spikelets. We recognize five types of enrichment axes: paraclades of the unit of inflorescence (UIF), paraclades of the trophotagma (TT) with exposed UIF; paraclades of the trophotagma with not exposed UIF; subterranean paraclades on short rhizomes and subterranean paraclades upon plagiotropic axes of long internodes. According to the enrichment axes, we differentiate six types of synflorescences. The different types of enrichment axes and synflorescences types are characterized; their differences determine in some cases the existence of fruit heteromorphism. Fil: Tivano, Juan. Universidad Nacional del Litoral; Argentina Fil: Perreta, Mariel Gladis. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The synflorescence structure of Cyperaceae is revised. It is postulated that the wide diversity shown by the synflorescences can be explained by the analysis of some processes that operate in different ways combined or independently. Twenty-five of such processes are identified and described as responsible for the great diversity detected in the synflorescences of Cyperaceae. Based on these processes, it is possible to recognize the origin of the different types of synflorescences. The paniculodium appears to be the basal unit of inflorescence within the Cyperaceae. Homogenization and truncation possibly are controlling the passage from Juncaceae to Cyperaceae. The diverse processes and the resulting structures were mapped in the phylogeny of the family, demonstrating that the trends of diversification of the synflorescence between the different tribes and within the tribes are mainly reductive.

The typology developed by Troll was followed to describe inflorescence structures for 15 species of Spartina. In all species here studied, truncation of the terminal spikelet of the main axis and primary paracladium was observed. The truncation can also involve the short paracladia subzone so that the inflorescence is confined to just the long paracladia subzone. A great homogenization of paracladia and maximum ramification degree limited generally to the second order of branching are distinctive characteristics of the genus. Proximal paracladia with third-order branching were found in only three specimens, and in these exceptional cases, the homogenization is partial. Sometimes, in some species, a subzone of long and short paracladia can be distinguished. The absence of trophotagma paracladia in all the species studied was verified. The variation in the structure of the inflorescence among species is due to the differences in the number of short paracladia, long paracladia, total number of primary paracladia and also in the angle of divergence of the long paracladia from the main axis. The latter, in addition to variations in the intercalary growth of the internodes produces modifications in the general appearance of the inflorescences. The systematic and taxonomic value of the inflorescences in Spartina is discussed.

The synflorescences of species related to Schizachyrium condensatum are typologically characterized. This species presents floriferous shoots with complex systems of ramification. In all species the inflorescence is polytelic and truncate. The typological pattern has been described and presents differences in the following parameters: length and shape of the synflorescence, paracladia of the trophotagma subzone and short paracladia subzone. A comparative analysis of the variations observed in the structure of the synflorescence is included Fil: Peichoto, Myriam Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Summary Melica macra Nees is a widespread grass of Central and Northern Argentina. It is considered an invasive weed in natural grasslands. The aim of the present paper is to describe the branching system of M. macra on the base of both the analysis of living plants obtained from seeds and maintained under cultivation, and the observation of plants growing in their natural habitat. The plants are cespitose and able to produce tillers profusely and bear a rhizomatous basal structure ensuring perenniality. Branching along the main axis occurs up to the sixth node, whereas branches of first-order axes are axillary of leaves 1–3, and those of higher-order axes mainly of the first and second leaves. Such higher-order axes are responsible for the formation of the basal rhizomatous structure, which arise as a result of sympodially arranged rhizome links, each of them consisting of four proximal short internodes (including the short hypopodium) of each tiller. The morphology of tillers is largely influenced by the phenological stage, so that tillers developed before and after flowering can be clearly distinguished.

The Boutelouinae subtribe is comprised of one monophyletic genus, Bouteloua, with 57 species inhabiting the semi-arid regions of the New World. The inflorescences show significant structural variations, which provides an interesting system to examine their morphological evolution and identify characters and processes that may help to understand the group systematics. The structure of inflorescences was studied in 25 species of Bouteloua. All the species covered under this study have truncated polytelic inflorescences. Structural variations in the inflorescence unit among species may be accounted for by: (1) symmetry of the inflorescence unit, (2) total number of long primary branches, (3) total number of spikelets per branch, (4) number of perfect flowers per spikelet, (5) number of rudimentary flowers, and (6) reproductive system. Homogenization and truncation processes account for the diversity of mature inflorescences that exists in Bouteloua. In this work, we discuss the systematic and taxonomic value of the inflorescence in the Boutelouinae subtribe. Fil: Pilatti, Vanesa. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina

Premise of research. Rhynchospora, one of the biggest genera of sedges, displays several spikelet and flower modifications and is one of a few genera where the pollination strategy changes from wind to insect pollination; however, the mechanisms that have promoted such diversity in the genus are unknown. We have performed a comparative study of spikelet and flower development of Rhynchospora from an evolutionary perspective to get insight into the bases of spikelet and flower evolution. Particularly, we investigate correlations between the change from wind to insect pollination that occur in the genus and the spikelet and flower traits. Methodology. The spikelet and flower development of nine species of Rhynchospora were studied using SEM images. Parsimony, maximum likelihood, and Bayesian reconstruction analyses were conducted to evaluate the evolutionary history of flower and spikelet developmental programs. Pivotal results. We identified seven morphological and developmental traits that vary among Rhynchospora species; ancestral character reconstructions show that the spikelet and flower morphology and their developmental pathways support the diversification of Rhynchospora lineages. Conclusions. Our results suggest that the evolution of spikelet and flower developmental programs in Rhynchospora may be related to the evolution of its pollination type and mating system. The evolution toward a bisexual spikelet and flowers in which the androecium develops faster than the gynoecium may represent important steps for the transition from a wind- to insect-pollination system. In addition, we found new traits of spikelets and flowers that may help to distinguish natural groups within Rhynchospora. Fil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina Fil: Reinheimer, Renata. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentina

Background and Aims: Inflorescence forms of panicoid grasses (Panicoideae) are remarkably diverse and they look very labile to human eyes; however, when performing a close inspection one can identify just a small subset of inflorescence types among a huge morphospace of possibilities. Consequently, some evolutionary constraints have restricted, to some extent, the diversification of their inflorescence. Developmental and genetic mechanisms, the photosynthetic type and plant longevity have been postulated as candidate constraints for angiosperms and panicoids in particular; however, it is not clear how these factors operate and which of these have played a key role during the grass inflorescence evolution. To gain insight into this matter the macroevolutionary aspects of panicoid inflorescences are investigated. Methods: The inflorescence aspect (lax versus condensed), homogenization, truncation of the terminal spikelet, plant longevity and photosynthetic type were the traits selected for this study. Maximum likelihood and Bayesian Markov chain Monte Carlo methods were used to test different models of evolution and to evaluate the existence of evolutionary correlation among the traits. Both, models and evolutionary correlation were tested and analysed in a phylogenetic context by plotting the characters on a series of trees. For those cases in which the correlation was confirmed, test of contingency and order of trait acquisition were preformed to explore further the patterns of such co-evolution. Key Results: The data reject the independent model of inflorescence trait evolution and confirmed the existence of evolutionary contingency. The results support the general trend of homogenization being a prerequisite for the loss of the terminal spikelet of the main axis. There was no evidence for temporal order in the gain of homogenization and condensation; consequently, the homogenization and condensation could occur simultaneously. The correlation between inflorescence traits with plant longevity and photosynthetic type is not confirmed. Conclusions: The findings indicate that the lability of the panicoid inflorescence is apparent, not real. The results indicate that the history of the panicoids inflorescence is a combination of inflorescence trait contingency and order of character acquisition. These indicate that developmental and genetic mechanisms may be important constraints that have limited the diversification of the inflorescence form in panicoid grasses. Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina Fil: Rua, Gabriel Hugo. Universidad de Buenos Aires; Argentina

In southern South America, Andropogon sect. Leptopogon is represented by both diploid and hexaploid species. In order to compare the synflorescence structures and floral arrays in relation to ploidy levels in species of Andropogon , the section Leptopogon was used as model. In this study, the synflorescence structure was typologically characterized. The structural analysis was based on the typology system developed by Troll and Weberling, which has proved useful in describing inflorescences. A comparative analysis of the variations observed in the structure of the synflorescence and a morphometric analysis using principal component analysis were carried out. These results revealed that diploid and hexaploid species present differences mainly in the following parameters: synflorescence length, number of internodes of the enrichment zone main axis, number of internodes and length of paracladia of the trophotagma, number of long paracladia per unit of inflorescence, length of hairs on articulated rachis internodes, pedicellate spikelet length, pedicellate spikelet width, pedicel width, length of hairs on pedicel, sessile spikelet length, awn length and floral system arrangements. This study provides a useful tool to distinguish between diploid and hexaploid species of Andropogon sect. Leptopogon . We propose naming the group of diploid species from Central and South America as the Andropogon selloanus complex.

Summary The term synflorescence has been used without a clear definition in Poaceae , and it has even been applied - without much precision-to structures with different levels of complexity. The use of the synflorescence concept requires first, a typological characterization of the structural plan of the whole plant, were the following zones can be recognized: main florescence, paraciadial zone, inhibition zone, and innovation zone. In some cases it is difficult to define the lower limit of the synflorescence because the basal tillers may develop and flower more or less sylleptically, but also function as innovation shoots. Therefore in agrostology the term synflorescence may be applied to the main axis excluding the basal branches. The use of the term should be confined to general comparative discussions.

Summary It is postulated that the wide diversity shown by the inflorescence of grasses can be explained by means of a fairly restricted number of processes which have mainly reductive characteristics. Depending on the mode of action of these processes, a means is proposed by which the origin of different types of inflorescences can be recognized. In all cases, the starting point is a panicle with primary and secondary branches, from which, following four major evolutionary trends, the origins of other structures can be determined.

Premise of the study: The understanding of homoplasic structures becomes more relevant when they are complex and define large angiosperm taxa. Inflorescence architecture usually fulfills both features, as happens with Cyperus, a genus with two taxonomical subdivisions characterized either by alternative expressions of Kranz anatomy (C3or C4) or inflorescence shape (condensed or lax). Those subdivisions are not completely congruent because at least one of these presumed characters has evolved several times. We focused a SEM study on the inflorescence development in species with condensed inflorescences and different photosynthetic anatomy to test the possibility that condensed inflorescences of subgen. Anosporum (C3anatomy) have evolved independently from those of subgen. Cyperus (C4anatomy). Methods: Freshly collected inflorescences of C. entrerianus, C. eragrostis, C. oxylepis, and C. incomtus were studied using stereoscopic and scanning electron microscopy. Key results: Condensed inflorescences of Cyperus species with C3and C4anatomy had differences in structure and development: (1) mature structure, (2) position of second-order branching initiation in the first developmental stage of the inflorescence, (3) main axis development and elongation, and branching development, (4) types of ramifications, (5) phyllotaxis and symmetry. Conclusions: Results support multiple origins of condensed inflorescences in Cyperus, based especially on differences in timing during development and elongation of the main axis and branches, branching pattern and phyllotaxis. Structure and development may be the key to using inflorescence morphology as an external feature to distinguish large natural groups within Cyperus based on vegetative anatomy. © 2012 Botanical Society of America. Fil: Guarise, Nicolas Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

Inflorescence development in Panicum maximum and Urochloa plantaginea was comparatively studied with scanning electron and light microscopy to test the transfer of P. maximum to Urochloa and to look for developmental features applicable to future cladistic studies of the phosphoenol pyruvate carboxykinase (PCK) subtype of C4 photosynthesis clade (P. maximum and some species of Brachiaria, Chaetium, Eriochloa, Melinis, and Urochloa). Eleven developmental features not discernable in the mature inflorescence were found: direction of branch differentiation; origins of primary branches; apical vs. intercalary development of the main axis; direction of spikelet differentiation; direction of glume, lemma and palea differentiation; position of the lower glume (in some cases); size of the floret meristem; pattern of distal floret development; pattern of gynoecium abortion; differential pollen development between proximal and distal floret; and glume elongation. Inflorescence homologies between P. maximum and U. plantaginea are also clarified. Panicum maximum and U. plantaginea differ not only in their mature inflorescence structure but also in eight fundamental developmental features that exclude P. maximum from Urochloa. The following developmental events are related to sex expression: size of floret meristem, gynoecium abortion, pollen development delay in the proximal floret, glume elongation and basipetal floret maturation at anthesis. Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

In grasses, inflorescence diversification and its correlation with species evolution are intriguing and not well understood. Part of this problem lies in our lack of comprehension about the inflorescence morphological complexity of grasses. We focused our study on the PCK clade (named for phosphoenol pyruvate carboxykinase), a well‐supported monophyletic group for which the relationships among its taxa are not well resolved. Interestingly, the PCK clade has an extensive diversity of adult inflorescence forms. A comparative developmental approach can help us to understand the basis of such morphological differences as well as provide characters that can be used in phylogenetic studies of the group. Using SEM studies, we demonstrate that inflorescence morphology in this clade is even more complex than what is typically observed in adult forms. We describe a number of new characters, and some classical features previously used for taxonomic purposes are redefined on the basis of development. We also define four morphological groups combining adult inflorescence form and development, and we discuss some of the evolutionary aspects of inflorescence diversification in the PCK clade. Taxonomic delimitation among genera in the PCK clade remains confusing and unclear where molecular and morphological studies support different classifications. Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Zuloaga, Fernando Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

The structure of the synflorescence and the flowering unit (inflorescence) in Commelinaceae are characterized. The synflorescence is polytelic and the basic inflorescence type is a terminal pedunculate thyrse with an indeterminate central axis to which several to many cincinni are attached. Each thyrse is a florescence, and each cincinnus is a partial florescence. Variations mainly in the number of cincinni and in the number of flowers on each cincinnus determines the main differences found in the inflorescences of the different genera. Hypothesized developmental processes are described, with a view to finding relationships among different models characterized in the family as well as defining characters for cladistic studies, which may be useful to depict all the variations observedand serve as a guide for future phylogenetic studies. Fil: Panigo, Elisa. Universidad Nacional del Litoral; Argentina Fil: Ramos, J.. Universidad Nacional del Litoral; Argentina Fil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Perreta, Mariel Gladis. Universidad Nacional del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral; Argentina

The architecture of the shoot branching system in Poaceae defines the growth forms within this family. The specific characteristics of the main axis as well as the disposition and characteristics of the lateral shoots determine the main structural variations found among species. In this work, we discuss the set of parameters to be taken into account in describing the vegetative structure of Poaceae in order to achieve a full diagnosis of the system and to thoroughly assess and interpret its variations. Fil: Perreta, Mariel Gladis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Ramos, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Tivano, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

Plant soil compaction poses a serious problem to agriculture because it produces different types of changes in plant characteristics. No method has been implemented to date to use root morphological changes as indicators of soil compaction levels. Therefore, the aim of the present study was to evaluate whether or not the morphological changes in root apexes of soybean (Glycine max (L.) Merrill) can be used as indicators of soil compaction levels. To this end, a silt-loamy soil material (from a Typic Argiudoll, Esperanza series), sieved through a 2 mm mesh was used and the following soil bulk density levels were determined: 1.1, 1.3 and 1.5 g cm3 for which the corresponding mechanical resistances were < 0.1, 0.5 and 3.5 MPa, respectively. The distance from the apex to the first tertiary root and the root diameter at 1.5 cm from the apex were measured on the secondary root apexes. A form factor equal to the quotient between these two variables was subsequently calculated. An inverse relationship between soil mechanical impedance and secondary root length and form factor as well as a direct relationship with the secondary root diameter were observed. Changes in rhizodermis cells were also recorded. The following morphological characteristics were found to evidence the highest sensitivity to soil compaction: i) the form factor, ii) rhizodermis papillose cells, iii) apical malformations in root hairs, and iv) root diameter in expansion areas. Taken together, the morphological characteristics of root apexes could be considered to be indicative of soil compaction. A compactação do solo causa severos problemas devido a que gera diferentes mudanças nas características das plantas. Não existem métodos que possibilitem o uso das mudanças da morfologia das raízes como indicadores de níveis de compactação do solo. Avaliaram-se se alterações morfológicas nos ápices de soja podem ser utilizadas como indicadores de graus de compactação do solo. Solo peneirado a 2 mm, classificado como Typic Argiudol (série Esperanza), foi compactado até atingir os seguintes valores de densidade do solo: 1.1, 1.3 e 1.5 g cm3, para os quais corresponderam os valores de resistência mecânica de < 0.1, 0.5 e 3.5 MPa, respectivamente. A distância desde o ápice até a primeira raiz terciária e o diâmetro a 1.5 cm desde o ápice foram medidos nas raízes secundarias. Um fator de forma foi calculado fazendo o quociente entre as duas variáveis medidas. Houve uma relação inversa entre o cumprimento da raiz secundaria e fator de forma com a resistência mecânica, e uma relação direta entre esta ultima e o diâmetro das raízes secundárias. Alterações nas células da rizoderme foram determinadas. As seguintes características morfológicas se mostraram muito sensíveis a compactação do solo: i) o fator de forma, ii) as células papilosas da rizoderme, iii) malformações apicais nos pelos das raízes, e iv) diâmetro das raízes em áreas de expansão. As características morfológicas dos ápices das raízes podem ser consideradas indicadores de compactação dos solos. Fil: Ramos, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Imhoff, Silvia del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Pilatti, Miguel Angel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

The architecture of the branching system in species of Pappophoreae (Poaceae) has not been studied in detail. This work covers the spatial and temporal variation of the shoot system in species of Cottea, Enneapogon, Kaokochloa, Pappophorum and Schmidtia (Pappophoreae). Growth form variation of the species of Pappophoreae is related to the different functions of the axillary buds. We identify six growth form models within Pappophoreae. These models represent reference points along a continuum of variations that are characteristic of certain genera or species within a genus. Fil: Tivano, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina