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congresos y reuniones científicas
Novel diversity in wild peanut relatives and the importance of their conservation in South America
SEIJO, J.G.; ROBLEDO, G.; ORTIZ, A. M.; GABRIELE, M.; SAMOLUK, S.; CARISSIMO, D.; KRAPOVICKAS, A.; LAVIA, G. I
Congreso; The 6th International Crop Science Congress (ICSC); 2012
International Crop Science Society
Most of the collections of Arachis germplasm have been performed during the 70´s, 80´s and 90´s when the accessibility to many of the natural localities where the species grow was very difficult, especially in Bolivia. Field collections performed during the last ten years, particularly in Bolivia and Argentina, allowed a better screening of the distribution of the genus in these countries and the collection of many samples of different species. The biosystematics analysis of these new materials together those present in ex-situ collections revealed novel variability in the wild germplasm. Taxonomically, 8-10 new species are being formally described. Morpho-anatomical studies revealed some new features, particularly in fruits. From a chromosome point of view, the species showed a wide variability in karyotype structure, which were used to arrange the species of section Arachis in a new genome classification. The isolation of DNA repetitive elements and the analysis of their distribution and representativeness in the karyotypes of the species, demonstrated that they are one of the most important component in determining the variations detected in the chromosome structure. Nuclear and chloroplast sequences of non-transcribed or spacer regions demonstrated a high variability among and within species. The nuclear 5S rDNA sequences showed that the alleles are restricted to species, while the variability detected in chloroplast marker is not restricted to species, but instead, it is geographically structured. The bulk of data strongly suggest that the variability present in nature is extremely underrepresented in the international and local germplasm banks of Arachis. In this context and because the habitats where Arachis species lived are being rapidly transformed, there is an urgent need of collection and evaluation of new materials to gain a comprehensive knowledge of the variability present in Arachis wild germplasm and to optimize its use in breeding programs.