Localization of ribosomal genes by FISH and CMA+ heterochromatic regions in two forage species, Arachis pintoi Krapov. & W:C: Gregory and A. repens Handro (Leguminosae), and their interspecific hybrid

PUCCIARIELLO ORNELLA; ORTIZ, ALEJANDRA MARCELA; FERNÁNDEZ, AVELIANO; LAVIA, GRACIELA INÉS

Buenos Aires

Simposio; The 6th International Symposium on the Molecular Breeding of Forage and Turf; 2010

The section Caulorrkizae includes two stoloniferous BraziIian species,Arachis repens and A. pintoi. Both species are economically importantlegurnes. A. pintoi is cultivatd as high-quality forage, while A. repensic cultivated as ornamental turf and forage. In order to combine theforage characteristics of A. pintoi with the resistance to pest anddiseases of A. repens, crosses between both have been camied out.Nevertheless, the plants obtained in such crosses did not produce seedsand at the present there is no evidence for he origin of this sterilib.In an attempt to infer the homology degree between parental entitiesand to contribute to elucidations of the genomic constitution of thehybrid, this work presents the karyotype comparison between thethree entities by classical and rnolecular cytogenetics. Both species, aswell as the interspecific hybrid, revealed the same karyotype formula(18m+2sm) and a pair of satellited chromosomes. This pair showed apair of proxirnal CMA+ bands in the three taxa, which correspond toheterochromatin associated with NORs, in coincidente with 45s rDNAloci. The nurnber of identified DAPI+ bands varied between 3 and 5,not being possible to decide the exact nurnber for each entity studied.The number of 5S rDNA sites varied between he taxa: four in A. pintoi,two in A. repens and thrm in the hybrid. Our results evidenced that,despite the differences in the nurmber of 5S rDNA sites, the parentalspecies and the hybrid present a high chromosomal homology degree,because they have the same karyotype fomula, nurmber of satelIitdchromosome pairs, number and localization of CMA+ bands and 45srDNA sites, thus indicating that A. pintoi and A. repens form a naturalgroup.