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Made available in DSpace on 2022-04-29T08:38:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Pollen morphology, ultrasculpture and ultrastructure were investigated for Poiretia in search of morphological characters of taxonomic importance using light microscopy as well as scanning and transmission electron microscopy. Additionally, principal components analysis was done to elucidate patterns of variation among the species. Pollen grains are small to medium size, isopolar, prolate spheroidal to prolate, 3-zonocolporate, colporus with operculum, membrane and margo are ornamented. Five pollen types are recognised and described based on mesocolpium exine ultrasculpture. Exine consists of a compact tectum, eutectate, tectate perforate to semitectate, the infratectum is collumelar and granular, foot layer discontinuous to absent in aperture region and endexine is continuous. A comprehensive description of the operculum, membrane ornamentations and the ultrastructure of exine were given for all species in the genus, nine of which were not previously analysed palynologically. Systematic implications of the palynological variations found in the literature and through light, scanning and transmission electron microscopical analyses were discussed. This article describes the importance of the characterisation of Poiretia pollen grains, which contributes to the systematics of the Adesmia informal clade. The class of endoaperture, ultrasculpture of mesocolpium and apocolpium, and ultrastructure of tectum, foot layer, and endexine support the eurypalynous status of Poiretia and are useful to recognise some species that have problematic delimitation (P. latifolia, P. coriifolia, P. unifoliolata, P. mattogrossensis, P. elegans, P. marginata) as well as groups of species. Programa de Pós-graduação em Biodiversidade Vegetal e Meio Ambiente Instituto de Botânica Núcleo de Pesquisa em Palinologia Instituto de Botânica Programa de Pós-graduação em Ciências Biológicas (Botânica) IBB Universidade Estadual Paulista Laboratório De Biotecnologia Vegetal Centro De Energia Nuclear Na Agricultura Universidade De São Paulo Programa de Pós-graduação em Ciências Biológicas (Botânica) IBB Universidade Estadual Paulista

Pollen grains of 23 species distributed in 15 genera and represented by 64 specimens were analysed using light and scanning electron microscopy to characterise the neotropical genera of Hippomaneae...

Barbacenia graminifolia is a Velloziaceae species endemic to the campos rupestres in Serra do Cipó, Minas Gerais state (Brazil). This biome is characterised by high irradiance and limited water conditions. Unlike other resurrection plants, B. graminifolia can maintain a high hydric status (80%) after 28 days of water suppression before desiccation. We investigated the physiological and metabolic mechanisms associated with structural changes that allow B. graminifolia to maintain hydration under a prolonged water deficit and to recover after desiccation. After 30 days of water deficit, desiccated plants exhibited chlorophyll degradation, a 178.4% and 193.7% increase in total carotenoids and MDA, respectively, and twice the CAT and APX activity compared to hydrated plants. The metabolite profile showed increased amino acids, carbohydrates, saturated fatty acids and benzoic acids during dehydration, while trichloroacetic acid cycle acids were higher in hydrated and rehydrated plants. Anatomical and ultrastructural data corroborated the physiological and metabolic changes and revealed the presence of mucilaginous cells with high water retention capacity. Our data indicated that combined strategies of assimilatory metabolism shutdown, accumulation of compatible solutes and antioxidant compounds, increase in hydrophilic molecules, changes in the composition of membrane lipids and remodelling of cell organelles conditioned the efficiency of B. graminifolia in delaying water loss, tolerating further desiccation and quickly recovering after rehydration. These attributes evidence that this species is well adapted to cope with adverse environmental conditions, mainly directing the metabolism to an efficient antioxidant response and improving its capacity to retain water during the dry season.

In situ hybridization with mRNA probes enables the detection and localization of gene expression in plant somatic embryogenesis samples. BbrizSERK is a gene that is expressed in embryogenic cells and tissues of Brachiaria. Here we describe methods used for in situ hybridization to localize BbrizSERK transcripts during somatic embryogenesis of Brachiaria brizantha according to the plant material and observations intended, using paraffin or butyl methyl methacrylate resin-embedded samples, as well as a method for whole-mount preparation applicable for the analysis of other genes involved in embryogenic processes, along with other in vitro processes.

Somatic embryogenesis has been obtained in many citrus cultivars; however, the efficiency of the system is genotype dependent and culture synchronization is important to reach more efficient systems. In this chapter we present a detailed protocol of somatic embryogenesis induction from nucellar tissue and the use of an alternative method of callus sieving for culture synchronization and embryo production. This is a simple method which can also be evaluated for other species aiming at better culture efficiency and somatic embryo production.

Protoplasts are an attractive explant source for biotechnological tools widely used on citrus genetic improvement, such as somatic hybridization and direct genetic transformation. These delicate and responsive materials are subjected to cell proliferation induction and differentiation of somatic embryos which further regenerate into entire plants. The isolation of viable protoplasts followed by regeneration of plants through somatic embryogenesis is an important methodology for breeding applications. The methods presented here can also be used as a reference for protoplast work in other species, followed by protocol optimization for different species/genotypes.

Hohenbergia is one the most diverse genus in Bahia state, inhabits almost all region of the state. As a result of ongoing studies on the genus Hohenbergia in Bahia, Brazil, here we describe and illustrate Hohenbergia erecta, endemic to the municipality of Mucugê, at Chapada Diamantina. Hohenbergia erecta differs from its morphologically related, H. catingae, by an elongated aspect provided by the tubular rosette (vs short stem with a crateriform rosette), and a once-branched cylindrical inflorescence (vs 2–3-brached pyramidal inflorescence), with branches congested at the apex (vs branches laxly arranged). Due to a small distribution area in the Caatinga forest and based on a spatial analysis we categorized it as Endangered (EN), following the IUCN criteria. Hohenbergia erecta is endemic of the central region of Chapada Diamantina, being described as dominant in the area, where no other Hohenbergia species inhabits. It is important, however, that new field expeditions are conducted in the region to observe the richness of the genus at Chapada Diamantina.

Aechmea (Bromeliaceae) is a large genus with controversial systematics and distinct flower shapes and pollinators. We explored floral anatomy and development in two Aechmea spp. belonging to different subgenera to contribute useful information on reproductive biology and taxonomy. We examined floral buds using scanning electron and light microscopy to characterize the development of septal nectaries, petal appendages, ovules, stamens and carpels. In A. gamosepala, we confirmed that the petal appendages develop late, whereas in A. correia-araujoi they develop earlier during floral development. Petal appendage formation included positional changes, possibly affecting floral attributes and visitation by insects, rather than vertebrates. Nectar is released through three basal orifices distally on the ovary, and here we document the link between the nectary region, through discrete canals, upward to the conduplicate lobes of the wet stigma. Improved understanding of the floral development and morphology of Aechmea may help to explain the existence of polymorphic flowers in this genus and may have implications for studies on interactions with pollinators and systematics.

We describe a new species of Hohenbergia (Bromeliaceae) from Brazil, H. ituberaensis, a rare species, so far only known from Ituberá municipality, Bahia State, in an area of the Atlantic Forest. The species is similar to H. stellata, presenting a pinkish inflorescence, congested and non-divided branches, pinkish and large floral bracts hiding the sepals, spatulate petals with a slightly reflexed apex. However, it differs by the white petals, as a diagnostic characteristic. The type specimen was collected in a small forest fragment and here this species is categorized as Vulnerable. Additionally, we compared this new species to Hohenbergia belemii and H. capitata, which are also similar to H. stellata, due to the red/pinkish characteristics of the branches, with large flowers and well-developed floral bracts. An illustration, an occurrence map, taxonomic comments and a table comparing the main characters of these four species are provided.

Comprehensive analysis of the FT/TFL1 gene family in Passiflora organensis results in understanding how these genes might be involved in the regulation of the typical plant architecture presented by Passiflora species. Passion fruit (Passiflora spp) is an economic tropical fruit crop, but there is hardly any knowledge available about the molecular control of phase transition and flower initiation in this species. The florigen agent FLOWERING LOCUS T (FT) interacts with the bZIP protein FLOWERING LOCUS D (FD) to induce flowering in the model species Arabidopsis thaliana. Current models based on research in rice suggest that this interaction is bridged by 14–3-3 proteins. We identified eight FT/TFL1 family members in Passiflora organensis and characterized them by analyzing their phylogeny, gene structure, expression patterns, protein interactions and putative biological roles by heterologous expression in Arabidopsis. PoFT was highest expressed during the adult vegetative phase and it is supposed to have an important role in flowering induction. In contrast, its paralogs PoTSFs were highest expressed in the reproductive phase. While ectopic expression of PoFT in transgenic Arabidopsis plants induced early flowering and inflorescence determinacy, the ectopic expression of PoTSFa caused a delay in flowering. PoTFL1-like genes were highest expressed during the juvenile phase and their ectopic expression caused delayed flowering in Arabidopsis. Our protein–protein interaction studies indicate that the flowering activation complexes in Passiflora might deviate from the hexameric complex found in the model system rice. Our results provide insights into the potential functions of FT/TFL1 gene family members during floral initiation and their implications in the special plant architecture of Passiflora species, contributing to more detailed studies on the regulation of passion fruit reproduction.

Made available in DSpace on 2022-04-28T19:48:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 With its accumulation in upland rice, cadmium (Cd) can easily enter the human food chain, which poses a global health threat considering nearly half of the human population depends on rice as a staple food source. A study was conducted to (1) evaluate Cd accumulation by rice cultivars, grown in Cd-polluted Tropical Oxisols, with different levels of Cd tolerance; (2) quantify Cd transfer from soil to rice shoots and grain; and (3) estimate daily Cd intake by humans. Three rice cultivars, characterized by low (Cateto Seda–CS), medium (BRSMG Talento–BT), and high (BRSMG Caravera–BC) Cd uptake capacity, were investigated. Rice cultivars were exposed to increasing soil Cd concentrations (0.0, 0.7, 1.3, 3.9, 7.8, and 11.7 mg kg−1). Analysis was performed on soil, shoots, and grain. Shoot biomass and grain yield decreased with increasing Cd supply, suggesting the following Cd tolerance: CS > BT > BC. Cadmium concentrations in shoots and grain increased when exposed to Cd. Only CS did not exceed the maximum Cd limit permitted in food (0.40 mg kg−1), when rates up to 1.3 mg kg−1 of Cd were applied to soil. Considering daily rice consumption levels in Brazil, Cd intake often exceeds maximum tolerable levels. Continuous monitoring of soil Cd concentrations is a pivotal step in avoiding hazards to humans. Such monitoring is important on a global scale since outside of Asia, Brazil is the leading rice-producing and rice-consuming country. Graphical abstract: [Figure not available: see fulltext.] Department of Plant Protection Rural Engineering and Soils School of Engineering São Paulo State University School of Agricultural and Veterinarian Sciences São Paulo State University, Via de acesso Prof. Paulo Donato Castellane, s/n Centre of Nuclear Energy in Agriculture Universidade de São Paulo Federal Institute of São Paulo Indian River Research and Education Centre Institute of Food and Agricultural Sciences University of Florida Department of Biology and Chemistry California State University Dipartimento Di Architettura Design E Urbanistica Università Degli Studi Di Sassari Desertification Research Centre Università Degli Studi Di Sassari Department of Plant Protection Rural Engineering and Soils School of Engineering São Paulo State University School of Agricultural and Veterinarian Sciences São Paulo State University, Via de acesso Prof. Paulo Donato Castellane, s/n

We here establish the Hohenbergia capitata complex composed of three species endemic to the Atlantic Forest, in the State of Bahia, Northeastern Brazil. When compared with other Hohenbergia species endemic to the Atlantic Forest, the complex is recognized by the small size of the plants (shorter than 1 m tall when flowering), lanceolate leaf blades, inflorescence with main axis short and congested branches, concentrated on the apical portion of the inflorescence (creating a capitulate shape), primary branches short pedunculate (short stipes), basal primary bracts sub-orbicular, large flowers (over 3 cm long) with spatulate petals with a cuspidate apex. Within this complex, we describe H. nidularioides sp. nov., a critically endangered species from the southern coastal region of Bahia, only known from a small fragment of Restinga forest in Una municipality. This species is very similar to H. capitata but differs by the nidular aspect of the inflorescence, which is only short-pedunculate and more or less hidden inside the rosette. In addition to the taxonomic treatment, we provide illustrations, the geographic distribution, taxonomic comments, and anatomical comparison of the species in the H. capitata complex.

Made available in DSpace on 2020-12-12T01:50:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The application of Se to plants growing under Cd contamination may become an alternative strategy to minimize Cd damage. However, there is no specific information available regarding whether Se can affect the anatomical structure and photosynthetic rates of plants under Cd stress. To address questions related to Se-protective responses under Cd stress, we evaluated the structural and ultrastructural aspects, photosynthetic rates and growth of tomato cv. Micro-Tom plants. Plants were exposed to 0.5 mM CdCl2 and further supplemented with 1.0 μM of selenite or selenate. The overall results revealed different trends according to the Se source and Cd application. Both Se sources improved growth, photosynthesis, leaf characteristics and middle lamella thickness between mesophyll cells. In contrast, Cd caused decreases in photosynthesis and growth and damage to the ultrastructure of the chloroplast. The number of mitochondria, peroxisomes, starch grains and plastogloboli and the disorganization of the thylakoids and the middle lamella in plants increased in the presence of Cd or Cd + Se. Se plays an important role in plant cultivation under normal conditions. This finding was corroborated by the identification of specific structural changes in Se-treated plants, which could benefit plant development. However, a reversal of Cd stress effects was not observed in the presence of Se. Universidade Estadual Paulista (UNESP) Faculdade de Ciências Agrárias e Veterinárias (FCAV) Departamento de Biologia Aplicada à Agropecuária Universidade de São Paulo (USP) Centro de Energia Nuclear na Agricultura (CENA) Universidade Estadual Paulista (UNESP) Faculdade de Ciências Agrárias e Veterinárias (FCAV) Departamento de Biologia Aplicada à Agropecuária FAPESP: 2017/04787-6 CNPq: 314380/2018-3 CAPES: Finance Code 001)

Nectar is an important floral resource in the establishment of plant-pollinator interactions. Recent studies have shown that nectariferous tissues are independent of the ABC model of floral development and that ecological interactions can modify their expression. In this sense, it would be interesting to study generalist species in relation to nectar production and nectary morpho-anatomy to verify the strategies used to attract different pollinator groups. We recorded nectar production dynamics in Aechmea vanhoutteana (Bromeliaceae) from a morpho-functional and ultrastructural perspective. We observed different species of hummingbirds, bees and butterflies visiting flowers of A.vanhoutteana, and their frequency varied throughout floral anthesis. The nectar volume and quantity of sugar also varied significantly during anthesis, and this spatial and temporal variability seems to be related to an increase in bee visits, representing an important aspect of the reproductive strategy of this species, since bees can fly longer distances than the observed hummingbirds (although both have territorial behaviours). Thus, it can be suggested that anatomical and physiological nectar traits may be related to pollen flow, an important aspect of the reproductive strategy of A. vanhoutteana, suggesting plant resource allocation for optimizing reproduction through nectar production.

—Araeococcus lageniformis is a new species described and illustrated here based on collections from the Atlantic Forest from the south of Bahia State, northeastern Brazil, and on morphological and anatomical characters. It is distinguished from A. nigropurpureus by the diameter of the tank, the morphology of the leaf, floral bracts, and sepals, by its sessile to nearly sessile flowers, its seed morphology, and by the presence of trichomes on both sides of the leaves. So far, the species is only known from Apuarema and Ibirapitanga municipalities. The type population was found in an unprotected area, fragmented by tracks and roads, where illegal logging takes place. Here we preliminarily assessed its conservation status as critically endangered.

In Euphorbiaceae tribe Hippomaneae is the pantropical genus Microstachys, comprised by 24 species, mostly from Brazil. Palynological studies with several representatives of the genus are sc...

Characterization of anther and ovule developmental programs and expression analyses of stage-specific floral marker genes in Gossypium hirsutum allowed to build a comprehensive portrait of cotton flower development before fiber initiation. Gossypium hirsutum is the most important cotton species that is cultivated worldwide. Although cotton reproductive development is important for fiber production, since fiber is formed on the epidermis of mature ovules, cotton floral development remains poorly understood. Therefore, this work aims to characterize the cotton floral morphoanatomy by performing a detailed description of anther and ovule developmental programs and identifying stage-specific floral marker genes in G. hirsutum. Using light microscopy and scanning electron microscopy, we analyzed anther and ovule development during 11 stages of flower development. To better characterize the ovule development in cotton, we performed histochemical analyses to evaluate the accumulation of phenolic compounds, pectin, and sugar in ovule tissues. After identification of major hallmarks of floral development, three key stages were established in G. hirsutum floral development: in stage 1 (early—EF), sepal, petal, and stamen primordia were observed; in stage 2 (intermediate—IF), primordial ovules and anthers are present, and the differentiating archesporial cells were observed, marking the beginning of microsporogenesis; and in stage 6 (late—LF), flower buds presented initial anther tapetum degeneration and microspore were released from the tetrad, and nucellus and both inner and outer integuments are developing. We used transcriptome data of cotton EF, IF and LF stages to identify floral marker genes and evaluated their expression by real-time quantitative PCR (qPCR). Twelve marker genes were preferentially expressed in a stage-specific manner, including the putative homologs for AtLEAFY, AtAPETALA 3, AtAGAMOUS-LIKE 19 and AtMALE STERILITY 1, which are crucial for several aspects of reproductive development, such as flower organogenesis and anther and petal development. We also evaluated the expression profile of B-class MADS-box genes in G. hirsutum floral transcriptome (EF, IF, and LF). In addition, we performed a comparative analysis of developmental programs between Arabidopsis thaliana and G. hirsutum that considered major morphoanatomical and molecular processes of flower, anther, and ovule development. Our findings provide the first detailed analysis of cotton flower development.

In Brachiaria brizantha BbrizSERK1, BbrizSERK2 and BbrizSERK3 were identified. SERK expression marks somatic embryogenesis, sexual MMC, and sexual and apomictic PMC. BbrizSERK3 might have a regulatory role in reproductive development. Somatic embryogenesis receptor-like kinase (SERK) consists of plasma membrane receptor genes that have been characterized in various species, associated with several aspects of plant development, including reproduction. SERK genes are involved in anther development and in early embryo development in sexual and asexual seed formation. To comprehend the complexity of the SERK genes and their function in Brachiaria reproduction, we performed a homology-based search in a genomic database of a sexual B. brizantha and identified sequences of three SERK genes, BbrizSERK1, BbrizSERK2, and BbrizSERK3. RNASeq data showed equivalent abundance of BbrizSERK1 and BbrizSERK2 transcripts in ovaries at early megasporogenesis of sexuals and apomicts, while BbrizSERK3 transcripts were more abundant in ovaries of sexuals than in apomicts. BbrizSERK3 results in three coding sequences due to alternative splicing, among them Variant 1 results in a protein with all the predicted domains of a SERK. BbrizSERK transcripts were detected in male reproductive tissues of both sexual and apomictic plants, suggesting a role in controlling anther development. BbrizSERK transcripts were detected early in ovule development, in the integuments, and in the megaspore mother cell of the sexual plant, but not in the cells that give rise to apomictic embryo sacs, suggesting a role in female reproductive development of sexuals. This paper provides evidences that SERK genes plays a role in the onset and establishment of somatic embryogenesis and in the reproductive development of B. brizantha and suggests a distinct role of BbrizSERK in apomixis initiation.

Nectar production dynamics can show inter- and intraspecific variation, which can be associated with environmental and ecological factors and with the ultrastructural diversity of the floral nectary. In this context, we recorded nectar production dynamics from a morphofunctional perspective using the hummingbird-pollinated Billbergia distachia (Bromeliaceae). The scale-throated hermit Phaethornis eurynome was the only floral visitor observed, indicating a specialized pollination system. Nectar production showed significant differences between day and night, and the periods of major pollinator activity and nectar secretion were synchronous. The ultrastructural features of the nectary showed some evidence of nectar reabsorption in flowers at night, and it can be inferred that this process may be a key factor in the nocturnal pause in nectar production. In this way, nectary morphoanatomy, nectar traits and an energy-saving mechanism through nectar reabsorption contribute to the well-established relationship between B. distachia and P. eurynome.

Flowers with heterodynamous stamens can present differences in the pollen grains of each stamen size group. Species of Aeschynomene L. present didynamous stamens (five long and five short) but little is known about their pollen dimorphism. The objective of this study was to increase the knowledge about the pollen characteristics in Aeschynomene and emphasize the possible morphological differences between the pollen grains of long and short stamens in order to contribute to ecological and taxonomic studies. Pollen grains from the two groups of stamens size of ten species were analyzed separately, according to the standard methodology for studies of pollen morphology. In addition, analyses of variance, comparison of means and base index were performed. The results showed that the amb, shape, endoaperture type and sexine ornamentation did not vary in the pollen grains of the long and short stamens in the same specimen, but they varied among the species. However, in relation to the size of the pollen grains of the two groups of stamens, four species presented significant differences regarding the size of the polar and equatorial axes. The pollen morphological data obtained considering the heteromorphism of the stamens can contribute to the knowledge of the repro ductive dynamics of the genus, and to the systematic studies.

Made available in DSpace on 2019-10-04T12:30:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-11-01 Brazilian Federal Government Agency Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Research Foundation Flanders - FWO Exposure to cadmium (Cd) can cause oxidative stress and injuries to the photosynthetic apparatus of plants. Otherwise, plant metabolism impaired by Cd toxicity can be aided by a proper sulfur (S) nutrition, since S is a component of antioxidants and photosynthetic systems. In this sense, our aim in this study was to evaluate the effect of S supply (0.1, 1.9 and 3.7 mmol L-1) on the antioxidant and photosynthetic systems of Massai grass exposed to Cd (0.0, 0.1 and 0.5 mmol L-1) as a prerequisite for studies of Cd phytoextraction. Plants supplied with 3.7 mmol L-1 S showed the lowest growth and the highest Cd concentrations when exposed to 0.5 mmol L-1 Cd. However, Massai grass grown without S deprivation showed the highest GSH + GSSG concentrations in all tissues and the lowest lipid peroxidation in stems and sheaths and roots. In general, the activities of SOD, CAT, APX, GPOX and GR did not increase in Massai grass exposed to Cd, even with proper S supply. Severe Cd exposure halted the photosynthetic system of Massai grass, although well-nourished plants with S exhibited greatest photosynthetic rate probably due to the action of GSH in the control of the oxidative stress. Univ Sao Paulo, Ctr Nucl Energy Agr, BR-13416000 Piracicaba, Brazil Hasselt Univ, Ctr Environm Sci, B-3590 Diepenbeek, Belgium Univ Fed Acre, BR-69920900 Rio Branco, Brazil Univ Sao Paulo, Luiz de Queiroz Coll Agr, BR-13418900 Piracicaba, Brazil Sao Paulo State Univ, BR-17602496 Tupa, Brazil Sao Paulo State Univ, BR-17602496 Tupa, Brazil CAPES: 1332394 FAPESP: 2014/16731-7 FAPESP: 2014/18735-0 FAPESP: 2015/21562-2 FAPESP: 2017/12367-7

Forage grasses belonging to the Urochloa (Brachiaria) genus present tolerance to Al toxicity, however there are intra- and interspecific differences among the species, which in turn should be better depicted. Here we evaluate genotypic differences in Al tolerance in four Urochloa (U. decumbens cultivar Basilisk; U. brizantha cultivar Marandu; U. brizantha cultivar Piata and U. brizantha cultivar Xaraes) cultivated in nutrient solution, during growth and regrowth. We analyzed the effect of Al uptake on epidermal and cell membrane damage, and lipid peroxidation in shoots and roots. Exposure of genotypes to Al concentration up to 1.33 mmol L−1 led to different degrees of shoot yield, mainly during the growth period. Increased Al concentration decreased dry matter production in shoots and roots, reduced leaf area (LA), relative root growth, increased Al accumulation in the roots and root-to-shoot Al translocation, notably during the first growth period. However, Al translocation from roots to shoots augmented massively in all genotypes, during the regrowth. Plant roots exposed to Al were damaged, exhibiting ruptures in the epidermis and reduced number of root hairs. Lipid peroxidation in shoots ranged in all genotypes exposed to Al, however, the oxidative stress was 2–5 times higher in shoots than in roots, notably in Marandu that accumulated 95% more Al than U. decumbens. This suggests that in the genotypes that are more tolerant to Al there is maintenance of metabolic activities, including upregulated and efficient antioxidant activity, root growth, LA growth and biomass yield.

There are no studies showing the S effect on root development and nutrient uptake in forage grasses used for Cd phytoextraction. In this sense, our aim in this study was to evaluate in an integrated manner the effect of S supply (0.1, 1.9, and 3.7 mmol L−1) on root development and nutrient uptake of Panicum maximum Jacq. cv. Massai (Massai grass) exposed to Cd (0.1, and 0.5 mmol L−1), and the implications of this effect for Cd phytoextraction. Root development of Massai grass was strongly inhibited when plants were exposed to 0.5 mmol L−1 Cd, but adequate S supply (1.9 mmol L−1) allowed for higher Cd uptake. On the other hand, there was a greater development of roots when Massai grass was exposed to 0.1 mmol L−1 Cd, while some strategies to restrict Cd entry, such as deposition of suberin and lignin in the endodermis and G-layer development, were observed. Adequate supply of S to these plants increased root length, root surface, Cd transport from roots to stems + sheaths, and N, S, and Mn concentrations.

Somatic embryogenesis is an important in vitro technique used to obtain Citrus sinensis (L.) Osbeck (sweet orange) plantlets for conservation, sanitation, propagation, and breeding. The induction of somatic embryogenesis from adult tissues of sweet orange could be an alternative to in vitro organogenesis from epicotyl segments, especially in seedless cultivars, where the latter is not feasible. The aim of this study was to obtain plantlets from ovary-derived somatic embryos of sweet orange cv. ‘Washington Navel’, an important seedless cultivar for citrus fresh fruit production. The explants used were pistils from flower buds, pre-anthesis, from 20-y-old plants cultivated in the field. Forty plantlets from 47 somatic embryos were obtained, in vitro-grafted, and acclimatized in greenhouse conditions. Ploidy evaluation through flow cytometric analysis, as well as the results of target region amplification polymorphism (TRAP) molecular markers confirmed the somatic origin of embryos as genetically similar to donor plants. This technique could be used for obtaining embryogenic cell suspension cultures or regenerated plants from mature tissues other than seed-derived tissues, especially for seedless genotypes.

Plant hybridization allows for the creation of new genotypes playing a strategic role in the development of new cultivars of interest for the horticultural trade, and is a central phenomenon in plant speciation processes. We worked with a plant family known as a case of Neotropical adaptive radiation, characterizing the reproductive systems selected species. This study aimed to identify the reproductive systems of sixteen bromeliad species, and to evaluate potential reproductive barriers in interspecific and intergeneric crosses. A total of 931 interspecific and intergeneric hybridization crosses were conducted in 80 different combinations involving 16 species belonging to five genera Aechmea, Ananas, Pseudananas, Alcantarea, and Vriesea. Reproductive systems were determined by controlled pollinations, and autogamy or self-incompatibility indexes. Fluorescence microscopy was used to evaluate pollen tube growth in the pistil. Seed germination was evaluated for each treatment. Over half of the species showed evidences of self-incompatibility: Aechmea bicolor, Ae. fasciata, Ae. nudicaulis, Ananas ananassoides, An. bracteatus, An. lucidus, An. parguazensis, Vriesea carinata, and V. paraibica. Among the self-compatible species, Ae. bromeliifolia, Ae. distichantha, and Pseudananas sagenarius presented autogamy. Alcantarea nahoumii, V. friburgensis, V. michaelii, and V. simplex exhibited no autogamy thus requiring pollinators. Agamospermy was observed in Ae. bromeliifolia, and Ae. distichantha. Crosses were successful in 43% of the attempts, corresponding to 32% of the species of the Ananas genus. Among the intergeneric crosses, only V. michaelii x Al. nahoumii and V. simplex x Al. nahoumii succeeded. Possible causes of self-incompatibility and incongruity in these crosses are related to different impediments to the pollen tube growth, such as an irregular deposition of callose on pollen tube; curling and arrest of pollen tube growth in the style, among others. It is suggested that the self-incompatibility is gametophytic, avoiding self-fertilization.

Several factors have contributed to bring pressure on agriculture. In this context, nanomaterial properties can be explored to design more efficient fertilizers and therefore increase productivity. In the present study, the roots of Phaseolus vulgaris were immersed in several nano ZnO dispersions for 48 h. The absorption and transport phenomena were in vivo monitored by X-ray fluorescence spectroscopy (XRF) and X-ray absorption spectroscopy (XAS). The nanoparticle size, concentration and coating with surfactants affected the rate of Zn release and therefore its uptake. In vivo X-ray absorption spectroscopy showed that Phaseolus vulgaris takes up Zn bound to both citrate and malate, while entire nanoparticles were only absorbed when roots were injured. X-ray fluorescence microanalysis unravelled that besides xylem bundles, root to shoot Zn transport can take place through the cortex.

There is a very large diversity in plant architecture in nature. Over the past few years, novel theoretical concepts and analytical methods have emerged as powerful tools to understand important aspects of plant architecture. Plant architecture depends on the relative arrangement of three types of organs: leaves, shoots, and flowers. During plant development, the architecture is modulated by the balance of two homologous proteins: FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1). The FT/TFL1 balance defines the plant growth habit as indeterminate or determinate by modulating the pattern of formation of vegetative and reproductive structures in the apical and axillary meristems. Here, we present a summarized review of plant architecture and primarily focus on the FT/TFL1 balance and its effect on plant form and development. We also propose passion fruit as a suitable model plant to study the effect of FT/TFL1 genes on plant architecture.

Tomato (Solanum lycopersicum) is a model for climacteric fleshy fruit ripening studies. Tomato ripening is regulated by multiple transcription factors together with the plant hormone ethylene and their downstream effector genes. Transcription Factors APETALA2a (AP2a), NON-RIPENING (NOR) and FRUITFULL (FUL1/TDR4 and FUL2/MBP7) were reported as master regulators controlling tomato fruit ripening. Their proposed functions were derived from studies of the phenotype of spontaneous mutants or RNAi knock-down lines rather than, as it appears now, actual null mutants. To study TF function in tomato fruit ripening in more detail, we used CRISPR/Cas9-mediated mutagenesis to knock out the encoding genes, and phenotypes of these mutants are reported for the first time. While the earlier ripening, orange-ripe phenotype of ap2a mutants was confirmed, the nor null mutant exhibited a much milder phenotype than the spontaneous nor mutant. Additional analyses revealed that the severe phenotype in the spontaneous mutant is caused by a dominant-negative allele. Our approach also provides new insight into the independent and overlapping functions of FUL1 and FUL2. Single and combined null alleles of FUL1 and FUL2 illustrate that these two genes have partially redundant functions in fruit ripening, but also unveil an additional role for FUL2 in early fruit development.

Distinct tomato genotypes possess different tolerance degree to cadmium (Cd), but the mechanisms behind this phenomenon are scarcely understood. To this end, the physiological, biochemical, anatomical, nutritional and molecular mechanisms associated to the plant tolerance against Cd toxicity were investigated in five tomato accessions with contrasting sensitivity to Cd exposure. Firstly, the data revealed that larger biomass loss was not always coupled to higher Cd concentration, indicating that other events, in addition to the internal Cd accumulation, impact tomato performance at early stages of Cd exposure. Secondly, the results indicated that the fine regulation of nutrient status, particularly magnesium (Mg), boron (B) and manganese (Mn), is associated to the mitigation of Cd toxicity. Magnesium status was coupled to the modulation of root development, resulting in changes in root hair formation and biomass allocation. Boron accumulation in leaves was linked to Cd toxicity, suggesting that tolerance mechanisms involved strategies to decrease or even avoid B excess in photosynthetic tissues. Disturbances in Mn status, i.e. Mn excess in leaves and Mn deficiency in roots, were also related to tomato sensitivity to Cd exposure. Thirdly, plant capacity to maintain leaf blade expansion is a relevant strategy for a better tomato development after short-term Cd exposure. Fourthly, tomato tolerance to Cd-induced stress does not depend on CAT activity enhancements in such conditions. In conclusion, tomato ability to quickly manage its nutritional status is necessary for alleviation of the Cd effects at early stages of exposure to this metal. The better understanding about tolerance mechanisms and mode of action of Cd toxicity in plants can help in the establishment of strategies to mitigate its impacts on crops.