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Unreduced (2n) gametes are the driving force that leads to polyploidization of plants in nature and an important tool for ploidy breeding. Peanut (Arachis hypogaea L., Leguminosae) seems most likely to have originated by sexual polyploidization through interspecific hybridization between the wild diploid relatives -A. duranensis and A. ipaënsis-, and subsequent binding of the unreduced gametes in the hybrid. Therefore, aiming to contribute to the understanding the event of polyploid origin of this important crop, we made diploid hybrids between A. duranensis and A. ipaënsis, and then investigated the production of unreduced gametes in the hybrids by analyzing the size range of pollen, the constitution of the sporads, and the microsporogenesis process. The meiotic abnormalities found, such as persistent bridges, tripolar spindles and cytomixis processes, would lead to the formation of restitution nuclei in both the first and second meiotic division. These failures in the regularityof meiosis lead to the formation of dyads and triads, and consequently to 2n pollen grains. These findings constitute the first evidence of the formation of unreduced gametes in intergenomic hybrids obtained between the wild progenitors of A. hypogaea and enable us to propose a model of origin of the crop through sexual polyploidization. Fil: García, Alejandra Vanina. 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: Ortiz, Alejandra Marcela. 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: Silvestri, María Celeste. 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: Custódio Alves, Raquel. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; Brasil Fil: Moretzsohn, M. C.. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; Brasil Fil: Lavia, Graciela Inés. 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: Silvestri, Maria Celeste. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Nordeste. Instituto de Botanica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botanica del Nordeste; Argentina

Peanut (Arachis hypogaea L.) is an important oilseed crop and food legume that is highly susceptible to biotic and abiotic factors. Wild Arachis species represent useful genetic resources because of their resistance to pests and diseases. In particular, understanding the affinity between B-genome species is important for broadening the genetic base of A. hypogaea (AABB genome), since only one population of A. ipaensis is known, and relatively few other species have been described. Therefore, we aimed to determine the genomic affinity between A. ipaensis and A. williamsii by developing hybrids. Microsatellite markers verified the hybrid status, and chromosome pairing and pollen viability results revealed that the species share high genomic affinity. Additionally, the presence of dyads detected in sporad and pollen analyses indicated the production of 2n gametes. These results will be useful for performing evolutionary studies and developing strategies for introgression programs to improve the B genome of A. hypogaea.

The species of the genus Arachis (Leguminosae) are ordered into nine sections. The assignment of genome types in this genus has been based on cross-compatibility analysis and molecular cytogenetic studies. The latter has also allowed karyotypically establishing well-defined genomes and reassigning the genome of several species. However, most of these studies have been focused mainly on the sections Arachis and Rhizomatosae. To increase the knowledge about the chromosome diversity of the whole genus, here we performed a detailed karyotype characterization of representative species of most of the sections and genomes of Arachis. This characterization included chromosome morphology, CMA/DAPI chromosome banding, and chromosome marker localization (rDNAloci and one satDNA sequence) by fluorescent in situ hybridization (FISH). Based on the data obtained and other previously published data, we established the karyotype similarities by cluster analysis and defined eleven karyotype groups. The grouping was partly coincident with the traditional genome assignment, except for some groups and some individual species. Karyotype similarities among some genomes were also found. The main characteristics of each karyotype group of Arachis were summarized. Together, our results provide information that may be beneficial for future cytogenetic and evolutionary studies, and also contribute to the identification of interspecific hybrids. Fil: Silvestri, María Celeste. 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: Ortiz, Alejandra Marcela. 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: Robledo Dobladez, Germán Ariel. 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: Lavia, Graciela Inés. 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

After the publication of our article, we noted one error on the figure 3. In the ideogram (figure 3) the signal of 5S rDNA loci illustrated with a striped signal over the long arm of chromosome 2 in proximal/interstitial position is not observed, probably for incompatibility with the format type of publication. Correct figure is as follows

Rhizomatosae is a taxonomic section of the South American genus Arachis, whose diagnostic character is the presence of rhizomes in all its species. This section is of particular evolutionary interest because it has three polyploid (A. pseudovillosa, A. nitida and A. glabrata, 2n = 4x = 40) and only one diploid (A. burkartii, 2n = 2x = 20) species. The phylogenetic relationships of these species as well as the polyploidy nature and the origin of the tetraploids are still controversial. The present study provides an exhaustive analysis of the karyotypes of all rhizomatous species and six closely related diploid species of the sections Erectoides and Procumbentes by cytogenetic mapping of DAPI/CMA heterochromatin bands and 5S and 18–26S rDNA loci. Chromosome banding showed variation in the DAPI heterochromatin distribution pattern, which, together with the number and distribution of rDNA loci, allowed the characterization of all species studied here. The bulk of chromosomal markers suggest that the three rhizomatous tetraploid species constitute a natural group and may have at least one common diploid ancestor. The cytogenetic data of the diploid species analyzed evidenced that the only rhizomatous diploid species—A. burkartii—has a karyotype pattern different from those of the rhizomatous tetraploids, showing that it is not likely the genome donor of the tetraploids and the non-monophyletic nature of the section Rhizomatosae. Thus, the tetraploid species should be excluded from the R genome, which should remain exclusively for A. burkartii. Instead, the karyotype features of these tetraploids are compatible with those of different species of the sections Erectoides and Procumbentes (E genome species), suggesting the hypothesis of multiple origins of these tetraploids. In addition, the polyploid nature and the group of diploid species closer to the tetraploids are discussed. Fil: Ortiz, Alejandra Marcela. 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: Robledo Dobladez, Germán Ariel. 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: Seijo, José Guillermo. 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: Valls, José Francisco Montenegro. Embrapa Recursos Genéticos e Biotecnologia; Brasil Fil: Lavia, Graciela Inés. 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

The genus Arachis is composed of 82 species (Krapovickas and Gregory 1994; Valls and Simpson 2005; Valls et al 2013; Santana and Valls 2015) mainly distributed within a large region of South America, which extends from the eastern foothills of the Andes Mountains in Bolivia and northern Argentina to the Atlantic coast in Brazil, and from the southern limit of the Amazonian rainforest towards the northern coast of La Plata River in Uruguay. Based on morphology, cross-compatibility, viability of the hybrids, geographic distribution and cytogenetics, the Arachis species have been arranged in nine taxonomic sections: Trierectoides, Erectoides, Procumbentes, Rhizomatosae, Heteranthae, Caulorrhizae, Extranervosae, Triseminatae and Arachis (Krapovickas and Gregory 1994; Fernández and Krapovickas 1994; Lavia 1996; Valls and Simpson 2005). Cross compatibility, karyotypic and meiotic analysis also allowed the identification and description of six different genomes within the section Arachis: namely A, B, D, F, K and G (Smartt et al 1978; Stalker 1991; Robledo and Seijo 2008, 2010; Robledo et al 2009; Silvestri et al 2015). The genomic constitution of the remaining species of the genus, in the absence of comprehensive cytogenetic and molecular analysis, is less precise and have been traditionally assigned on the basis of the subgeneric divisions, that is: Am (Heteranthae), C (Caulorrhizae), E (Trierectoides, Erectoides and Procumbentes), Ex (Extranervosae), T (Triseminatae) and R (Rhizomatosae) (Smartt and Stalker 1982). Classical and modern molecular cytogenetics revealed a huge variability within and among species of different sections. These studies provided important information about the complexity of the peanut genome, and were very useful to unravel the taxonomy of the genus and to establish relationships among the wild species with the cultivated peanut. Here we present an update of the cytological information on Arachis species, and some examples in which the use of chromosome markers were decisive to understand critical and long lasting problems in the genus. Fil: Seijo, José Guillermo. 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: Samoluk, Sergio Sebastián. 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: Ortiz, Alejandra Marcela. 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: Silvestri, María Celeste. 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: Chalup, Laura María Isabel. 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: Robledo Dobladez, Germán Ariel. 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: Lavia, Graciela Inés. 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

The genus

The meiotic behavior and pollen viability of the tetraploids (2n = 4x = 40) Arachis glabrata and A. nitida were analyzed aiming to provide insights into the nature of these polyploids and into the mechanism that determines the low seed production of these species. Meiotic analysis revealed 21 different chromosome configurations at diakinesis-metaphase I in A. glabrata (from 20 II to 4 II + 8 IV) and 7 in A. nitida (from 20 II to 2 I + 12 II + 2 III + 2 IV). The multivalent associations (up to 8 IV) observed in some A. glabrata metaphases suggest that this species may have an autopolyploid origin. However, the fact that the mean number of bivalents varied among accessions indicates different degrees of diploidization among them. In contrast, the multivalents (up to 2 III + 2 IV) observed in very low frequency in A. nitida indicate that this species may be either a largely diploidized autopolyploid or a segmental allopolyploid. A great diversity, although in low frequency, of meiotic abnormalities (abnormal chromosome orientation and segregation, chromosome bridges, irregular spindles, micronuclei, aneuploid nuclei, restitution nuclei, microcytes, monads, dyads, triads, and hexads) was detected in both species. The meiotic indexes were over 95%, and pollen viabilities ranged from 83.20 to 95.99%. These results suggest that chromosome behavior during meiosis would not severely affect pollen viability. Thus, the irregular chromosome behavior caused by the autopolyploid or segmental allopolyploid nature of these species may not be related to their low seed set production.

Polyploidy is a dominant feature of flowering-plant genomes, including those of many important crop species. Arachis is a largely diploid genus with just four polyploid species. Two of them are economically important: the cultivated peanut and A. glabrata, a tropical forage crop. Even though it is usually accepted that polyploids within papilionoid legumes have arisen via hybridization and further chromosome doubling, it has been recently suggested that peanut arose through bilateral sexual polyploidization. In this paper, the polyploid nature of the recent, spontaneously originated triploid cytotype of the tropical lucerne, A. pintoi, was analysed, and thereby the mechanism by which polyploids may arise in the genus.Chromosome morphology of 2x and 3x A. pintoi was determined by the Feulgeńs technique and the rDNA sites were mapped by FISH. To investigate whether polyploidization occurred by means of unreduced gametes, a detailed analysis of the microsporogenesis and pollen grains was made.The 2x and 3x plants presented 9m + 1sm and a satellited chromosome type 2 in each haploid genome. Physical mapping revealed a cluster of 18S-26S rDNA, proximally located on chromosome 6, and two 5S rDNA loci on chromosomes 3 and 5. Diploid plants presented 10II in meiosis while trivalents were observed in all triploids, with a maximum of 10III by cell. Diploid A. pintoi produced normal tetrads, but also triads, dyads and monads. Two types of pollen grains were detected: (1) normal-sized with a prolate shape and (2) large ones with a tetrahedral morphology.Karyotype and meiotic analysis demonstrate that the 3x clone of A. pintoi arose by autopolyploidy. The occurrence of unreduced gametes strongly supports unilateral sexual polyploidization as the most probable mechanism that could have led to the origin of the triploid cytotype. This mechanism of polyploidization would probably be one of the most important mechanisms involved in the origin of economically important species of Arachis, either by triploid bridge or bilateral sexual polyploidization.

The karyotype structure of Arachis trinitensis was studied by conventional Feulgen staining, CMA/DAPI banding and rDNA loci detection by fluorescence in situ hybridization (FISH) in order to establish its genome status and test the hypothesis that this species is a genome donor of cultivated peanut. Conventional staining revealed that the karyotype lacked the small "A chromosomes" characteristic of the A genome. In agreement with this, chromosomal banding showed that none of the chromosomes had the large centromeric bands expected for A chromosomes. FISH revealed one pair each of 5S and 45S rDNA loci, located in different medium-sized metacentric chromosomes. Collectively, these results suggest that A. trinitensis should be removed from the A genome and be considered as a B or non-A genome species. The pattern of heterochromatic bands and rDNA loci of A. trinitensis differ markedly from any of the complements of A. hypogaea, suggesting that the former species is unlikely to be one of the wild diploid progenitors of the latter. © 2010, Sociedade Brasileira de Genética. Fil: Robledo Dobladez, Germán Ariel. 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. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina Fil: Lavia, Graciela Inés. 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: Seijo, José Guillermo. 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. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina

Gleditsia amorphoides (Griseb.) Taub. is a tree species native to South America. It is known for its good quality wood and for its fruits that contain a rubber for industrial uses. One of the causes for the reduction of the production of viable seeds in forest trees is the damage caused by predators of fruits and seeds. The relationship between fruit production and predators is not known for G. amorphoides. Therefore, in this study, we evaluated the fruit production in this three species and the abundance of specimens of the Subfamily Bruchinae associated to G. amorphoides. The study was carried out in three localities of the Formosa Province in the Northeast of Argentina for three consecutive years. We found a single species of Bruchinae, identified as Bruchidius endotubercularis Arora. The results showed the existence of variability in the production of G. amorphoides fruits between years, but not between locations. The abundance of insects remained constant, not responding to the variation in the production of fruits between years. In this study, we report for the first time, the occurrence of B. endotubercularis associated with G. amorphoides in Argentina

Arachis hypogaea is a natural, well-established allotetraploid (AABB) with 2n = 40. However, researchers disagree on the diploid genome donor species and on whether peanut originated by a single or multiple events of polyploidization. Here we provide evidence on the genetic origin of peanut and on the involved wild relatives using double GISH (genomic in situ hybridization). Seven wild diploid species (2n=20), harboring either the A or B genome, were tested. Of all genomic DNA probe combinations assayed, A. duranensis (A genome) and A. ipaensis (B genome) appeared to be the best candidates for the genome donors because they yielded the most intense and uniform hybridization pattern when tested against the corresponding chromosome subsets of A. hypogaea. A similar GISH pattern was observed for all varieties of the cultigen and also for A. monticola. These results suggest that all presently known subspecies and varieties of A. hypogaea have arisen from a unique allotetraploid plant population, or alternatively, from different allotetraploid populations that originated from the same two diploid species. Furthermore, the bulk of the data demonstrated a close genomic relationship between both tetraploids and strongly supports the hypothesis that A. monticola is the immediate wild antecessor of A. hypogaea. Fil: Seijo, José Guillermo. 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. Universidad Nacional del Nordeste; Argentina Fil: Lavia, Graciela Inés. 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: Fernandez, Aveliano. 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. Universidad Nacional del Nordeste; Argentina Fil: Krapovickas, Antonio. Universidad Nacional del Nordeste; Argentina Fil: Ducasse, Daniel Adrián. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Bertioli, David J.. Universidade Catolica de Brasilia; Fil: Moscone, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

The 5S and the 18S-25S rRNA genes were physically mapped by fluorescent in situ hybridization (FISH) in all botanical varieties of cultivated peanut Arachis hypogaea (2n = 4x = 40), in the wild tetraploid A. monticola, and in seven wild diploid species considered as putative ancestors of the tetraploids. A detailed karyotype analysis including the FISH signals and the heterochromatic bands was carried out. Molecular cytogenetic landmarks are provided for the construction of a FISH-based karyotype in Arachis species. The size, number, and chromosome position of FISH signals and heterochromatic bands are similar in all A. hypogaea varieties and A. monticola, but vary among the diploid species. Genome constitution of the species is discussed and several chromosome homeologies are established. The bulk of the chromosome markers mapped, together with data on geographical distribution of the taxa, suggest that peanut originated upon domestication of A. monticola and evidence that the diploids A. duranensis and A. ipaensis are the most probable ancestors of both tetraploid species. Allopolyploidy could have arisen by a single event or, if by multiple events, always from the same diploid species. Fil: Seijo, José Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Lavia, Graciela Inés. 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: Fernandez, Aveliano. 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: Krapovickas, Antonio. 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: Ducasse, Daniel Adrián. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina Fil: Moscone, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Most species of the genus Arachis (Leguminosae; 80 spp.) are diploid with x=10 and only four species have x=9 chromosomes. Three of these x=9 species belong to section Arachis and are morphologically and chromosomally similar. To study the homeology of the genomes of x=9 species and their relation to other genomes in section Arachis we applied fluorescence in situ hybridization (FISH) of 18S-26S and 5S rDNA and 4´, 6-diamidino-2-phenylindole (DAPI) banding. FISH revealed for these three species one pair of 5S rDNA sites interstitially within the short arm of the metacentric pair 6 and one pair of 18S-26S rDNA sites in the proximal region of the long arm of the SAT chromosomes. Conspicuous DAPI+ bands were detected pericentromerically in all nine chromosome pairs of A. decora and A. praecox and in all but one pair of A. palustris. Our results suggest that all three species with x=9 of section Arachis share the same genome type and are different from the other genome types A, B, D, F, and K described for this section. Apparently, the x=9 species of section Arachis form a monophyletic group characterized by a genome type that we propose to call G genome. Fil: Silvestri, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura; Argentina Fil: Ortiz, Alejandra Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura; Argentina Fil: Lavia, Graciela Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura; Argentina

Meiotic behaviour of A. lignosa, A. rigonii (Sect. Procumbentes), A. microsperma, A. simpsonii and A. williamsii (Sect. Arachis) is reported for the first time, and for A. batizocoi, A. stenosperma and A. villosa were studied in different accessions than the previously reported ones. All the species analyzed were diploid forming 10 II at diakinesis-metaphase I, except A. stenosperma which presented 8 II+ 1 IV in 3% of the pollen mother cells. Most of the bivalents were of the ring type, and only 1 or 2 bivalents were usually of the rod type. Chiasmata were always located in distal to terminal position even at diplotene and diakinesis. Normal segregation of bivalents was observed which is in accordance with the recorded high pollen stainability. Only 1 pair of chromosomes was easily recognized, that being the very small “A” pair in the A genome of Arachis section species. This small pair can be used also at meiosis to distinguish the A and B genomes. Key words Arachis;Meiosis;A and B genomes.

Summary: Karyotypes of three diploid species belonging to sections Erectoides (Arachis hermannii), Procumbentes (A. rigonii) and Rhizomatosae (A. burkartii) were analyzed by Feulgen’s technique. The karyotype formula was different in each of the taxa analyzed: 2n=2x=16m+4sm in A. hermannii, 2n=2x=18m+2sm in A. rigonii, and 2n=2x=20m in A. burkartii. All species had a pair of satellited chromosomes, which corresponded to type 2 in A. hermannii, type 9 in A. rigonii, and type 8 in A. burkartii. Arachis hermannii and A. rigonii presented chromosomal features similar to those of the other species included in their respective sections. However, A. burkartii showed chromosome characteristics different from those found in the rest of the species of section Rhizomatosae.Key words: Arachis hermannii, A. rigonii, A. burkartii, chromosomes, phylogenetic relationships.Resumen: Estudios cariotípicos en especies silvestres de Arachis (Leguminosae) pertenecientes a las secciones Erectoides, Procumbentes y Rhizomatosae. Los cariotipos de tres especies diploides pertenecientes a las secciones Erectoides (A. hermannii), Procumbentes (A. rigonii) y Rhizomatosae (A. burkartii) fueron analizados mediante la técnica de Feulgen. Las fórmulas cariotípicas obtenidas son diferentes en los taxones analizados, 2n=2x=16m+4sm en A. hermannii, 2n=2x=18m+2sm en A. rigonii, y 2n=2x=20m en A. burkartii. Las tres especies presentaron un par de cromosomas con satélite, en A. hermannii tipo 2, en A. rigonii tipo 9 y en A. burkartii tipo 8. Arachis hermannii y A. rigonii presentaron características cromosómicas similares a las especies incluidas en sus respectivas secciones. Sin embargo, A. burkartii no comparte características cromosómicas con el resto de las especies de la sección Rhizomatosae.Palabras clave: Arachis hermannii, A. rigonii, A. burkartii, cromosomas, relaciones filogenéticas.

New chromosome numbers of seven peanut species, A. cryptopotamica Krapov. and W.C. Gregory and A. douradiana Krapov. and W.C. Gregory (Sect.Erectoides), A. subcoriacea Krapov. and W.C. Gregory and A chiquitana Krapov.,W.C. Gregory and C.A. Simpson (Sect. Procumbentes), A. cruziana Krapov., W.C.Gregory and C.A. Simpson, A. Herzogii Krapov., W.C. Gregory&C.A. Simpson and A. Simpsonii Krapov. and W.C. Gregory (Sect. Arachis) have been determined,all of them have 2n=20. SAT chromosomes were analysed for all species and a new type of satellited chromosome was described for the genus, which was named 3B for its close resemblance to the first described 3 type. “A” chromosomes were only found in A. Herzogii, A. Simpsonii and A. chiquitana from all the studied species. The last one belong to the section Procumbentes, however, the type of satellited chromosome and the presence of “A” chromosomes in its karyotype suggest that it should be moved from section Procumbentes. The presence of "A" chromosomes prov...

A. palustris Krapov., W. C. Gregory et Valls and A. praecox Krapov., W. C. Gregory et Valls, wild annual relatives of the cultivated peanut, belong to sect. Arachis. These species have qualities which deserve being incorporated into the cultivated peanut. Karyotypes were analysed, being for both species 2n=2x=18= 16m+ 2sm. The chromosome number of A. praecox is reported for the first time. Both species can be distinguished by a combination of parameters : karyotype formula, chromosome length, type and position of SAT chromosome, size of satellite and asymmetry indices. Knowledge about the chromosome number and karyotypes of both species is of great value for the improvement of cultivated peanut. The basic number x = 9 may have derived from ancestral x = 10 probably by aneuploidy. This fact supports the hypothesis that section Arachis is the one which presents the most advanced traits within the genus.

Plants were regenerated from cultured excised leaf segments ofTurnera ulmifolia (2n = 6x = 30). Cytological studies have demonstrated that chromosome doubling occurred in 100% of the regenerated plants. Probably it was produced by endomitosis, induced by excess of auxins in relation to cytokinins. High bivalent and low quadrivalent frequency, and univalents to octovalents were observed in metaphase I; lagging chromosomes were also found. Probably, the presence of multivalents may be due to the pairing among homoeologous chromosomes because the mother plant is a segmental allohexaploid. The high bivalent frequency may have been caused by preferential pairing of identical chromosomes against the homologous.

The karyomorphology for eight diploid species of Arachis belonging to three sections has been described for the first time, Sect. Extranervosae: A. macedoi (2n = 20m) and A. retusa (2n = 14m + 6sm); Sect. Heteranthae: A. sylvestris (2n = 16m + 4sm); Sect. Procumbentes: A. chiquitana (2n = 18m + 2sm); Sect. Arachis: A. cruziana (2n = 18m + 2sm), A. herzogii (2n = 18m + 2sm), A. simpsonii (2n = 20m) and A. williamsii (2n = 20m). A pair of satellited chromosomes was observed in all species. A chromosomes were found in A. chiquitana, A. herzogii and A. simpsonii. Karyotypic differences between sections were observed, but not enough to establish a characteristic karyotype pattern for each section. However, the species may be differentiated by the presence of A chromosomes, the type and position of satellites, and the karyotype formulae. These results are discussed with regard to karyotype evolution in Arachis to contribute to understanding the role of chromosome changes in the evolution of the genus. Fil: Lavia, Graciela Inés. 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: Ortiz, Alejandra Marcela. 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: Fernandez, Aveliano. 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. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina

Section Arachis of the homonymous genus includes 29 wild diploid species and two allotetraploids (A. monticola and the domesticated peanut, A. hypogaea L.). Although, three different genomes (A, B and D) have been proposed for diploid species with x = 10, they are still not well characterized. Moreover, neither the relationships among species within each genome group nor between diploids and tetraploids (AABB) are completely resolved. To tackle these issues, particularly within the A genome, in this study the rRNA genes (5S and 18S-26S) and heterochromatic bands were physically mapped using fluorescent in situ hybridization (FISH) in 13 species of Arachis. These molecular cytogenetic landmarks have allowed individual identification of a set of chromosomes and were used to construct detailed FISH-based karyotypes for each species. The bulk of the chromosome markers mapped revealed that, although the A genome species have a common karyotype structure, the species can be arranged in three groups (La Plata River Basin, Chiquitano, and Pantanal) on the basis of the variability observed in the heterochromatin and 18S-26S rRNA loci. Notably, these groups are consistent with the geographical co-distribution of the species. This coincidence is discussed on the basis of the particular reproductive traits of the species such as autogamy and geocarpy. Combined with geographic distribution of the taxa, the cytogenetic data provide evidence that A. duranensis is the most probable A genome ancestor of tetraploid species. It is expected that the groups of diploid species established, and their relation with the cultigen, may aid to rationally select wild species with agronomic traits desirable for peanut breeding programs.

Genome size of 16 species of Arachis L. with x = 10 and three with x = 9 was determined. DNA content (2C) between all diploid species, varies from 2.87 pg in A. retusa to 6.59 pg in A. douradiana. Considering species with 2n = 2x = 20 of all the sections, it suggests that in the evolution of Arachis genome, both increases and diminutions of DNA content would have occurred. Species with greater DNA content are included in sections believed to have a more recent origin, whereas those that contain minor DNA belong to the oldest sections; therefore, we propose genome evolution of Arachis toward higher DNA content. Origin of the basic chromosome number x = 9 is discussed considering genome size variation between species with x = 10 and x = 9. Reduction of the DNA content after the polyploidization would have happened in A. hypogaea. Fil: Lavia, Graciela Inés. 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: Fernandez, Aveliano. 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

En este trabajo se presentan los números cromosómicos de 26 accesiones del géneroSida(Malvaceae) de Argentina, Bolivia, Brasil, México y Paraguay, pertenecientes a 15 especies. Para las siguientes 8 especies se cita el número cromosómico por primera vez:S. CharpiniiKrapov. 2n=14,S. ciliarisL. 2n=16,S. MonteiroiKrapov. 2n=16,S. anomalaA. St.-Hil. 2n=16,S. CristobalianaKrapov. 2n=32,S. dubiaA. St.-Hil. & Naudin 2n=14,S. Poeppigiana(K.Schum.) Fryxell 2n=14 yS. LeitaofilhoiKrapov. 2n=14.

En este trabajo se presentan los primeros recuentos para H. Pohlii Gürke e H. Wilsonii Fryxellpertenecientes a la sección Furcaria. Ambas especies poseen 2n=72

Fil: Fernández, Aveliano. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina. Fil: Fernández, Aveliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica del Nordeste; Argentina. Fil: Krapovickas, Antonio. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; Argentina. Fil: Krapovickas, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica del Nordeste; Argentina. En este trabajo se presentan los números cromosómicos de 50 accesiones de Malvaceae deArgentina, Bolivia, Brasil, Chile, México y Paraguay, las mismas representan 17 géneros y 40especies. Para las siguientes 28 especies se presenta el número cromosomico por primeravez: Cienfuegosia conciliata 2n=20, Hibiscus striatus 2n=52, H. adscensionis 2n=72,Phragmocarpidium Heringeri 2n=50, Malachra radiata 2n=56, Pavonia Friesii 2n=56, P.fruticosa 2n=56, P. subrotunda 2n=56, Monteiroa Reitzii 2n=20, Tarasa nototrichoides 2n=10,Tropidococcus pinnatipartitus 2n=24, Cristaria disssecta 2n=12, Gaya Bordasii 2n=12,Pseudabutilon cinereum 2n=16, Abutilon fluviatile 2n=16, A. laxum 2n=16, Wissadula Fadyenii2n=14, Sida vespertina 2n=14, S. Glaziovii2n=28, S. glomerata 2n=14, S. hirsutissima 2n=28,S. planicaulis 2n=28, S. Rodrigoi, 2n=28, S. ulmifolia 2n=28, S. Hatschbachii 2n=42, S. Reitzii2n=42, S. aggregata 2n=16, S. rufescens 2n=32. Chromosome numbers are reported for 50 collections of Malvaceae from Argentina, Bolivia,Brasil, Chile, Mexico and Paraguay representing 17 genera and 40 species. First chromosomecounts are reported for the following 28 species: Cienfuegosia conciliata 2n=20, Hibiscusstriatus 2n=52, H. adscensionis 2n=72, Phragmocarpidium Heringeri 2n=50, Malachra radiata2n=56, Pavonia Friesii 2n=56, P. fruticosa 2n=56, P. subrotunda 2n=56, Monteiroa Reitzii2n=20, Tarasa nototrichoides 2n=10, Tropidococcus pinnatipartitus 2n=24, Chstaria disssecta2n=12, Gaya Bordasii 2n=12, Pseudabutilon cinereum 2n=16, Abutilon fluviatile 2n=16, A.laxum 2n=16, Wissadula Fadyenii 2n=14, Sida vespertina 2n=14, S. Glaziovii 2n=28, S.glomerata 2n=14, S. hirsutissima 2n=28, S. planicaulis 2n=28, S. Rodrigoi 2n=28, S. ulmifolia2n=28, S. Hatschbachii 2n=42, S. Reitzii 2n=42, S. aggregata 2n=16, S. rufescens 2n=32.