Novel diversity in wild peanut relatives and the importance of their conservation in South America

SEIJO G.; ROBLEDO, G.; ORTÍZ A.; GRABIELE M.; SAMOLUK S.; CARÍSIMO D.; KRAPOVICKAS A.; LAVIA, G.

Bento Gonçalves, RS

Congreso; 6th International Crop Science Congress; 2012

Most of the collections of Arachis germplasm have been performed during the 70´s, 80´sand 90´s when the accessibility to many of the natural localities where the species growwas very difficult, especially in Bolivia. Field collections performed during the last tenyears, particularly in Bolivia and Argentina, allowed a better screening of the distributionof the genus in these countries and the collection of many samples of different species. Thebiosystematics analysis of these new materials together those present in ex-situ collectionsrevealed novel variability in the wild germplasm. Taxonomically, 8-10 new species arebeing formally described. Morpho-anatomical studies revealed some new features,particularly in fruits. From a chromosome point of view, the species showed a widevariability in karyotype structure, which were used to arrange the species of section Arachisin a new genome classification. The isolation of DNA repetitive elements and the analysisof their distribution and representativeness in the karyotypes of the species, demonstratedthat they are one of the most important component in determining the variations detected inthe chromosome structure. Nuclear and chloroplast sequences of non-transcribed or spacerregions demonstrated a high variability among and within species. The nuclear 5S rDNAsequences showed that the alleles are restricted to species, while the variability detected inchloroplast 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 extremelyunderrepresented in the international and local germplasm banks of Arachis. In this contextand because the habitats where Arachis species lived are being rapidly transformed, there isan urgent need of collection and evaluation of new materials to gain a comprehensiveknowledge of the variability present in Arachis wild germplasm and to optimize its use inbreeding programs.