Reorganización genómica de las especies 2n = 20 de la sección Arachis.

ROBLEDO, G; SEIJO, JG

Congreso; VII Encuentro Internacional de Especialistas en Arachis. V International Legumes Conference; 2010

GENOMIC REORGANIZATION OF SPECIES 2N = 20 OF ARACHIS SECTION Germán Robledo & Guillermo Seijo IBONE. Corrientes. Argentina   Genome types A, B and D of section Arachis were originally established on the basis of karyotype morphology and cross compatibility assays of a few species. Currently. 26 species with 2n = 2x = 20 are included in the section, which were assigned to the A and B genomes. However, the interspecific hybrids fertility is not consistent with this genomic scheme, and the preliminary studies of molecular cytogenetics on a few species suggest a more heterogeneous karyotype. Therefore, in order to reappraise the genomic composition of the section we conducted a detailed karyotypic characterization of these species by analyzing the distribution patterns of C-DAPI+ heterochromatin and ribosomal genes by FISH. This study revealed a high karyotype variability, upon which five karyotypic groups were established. Each one has a distinctive structural organization. Two of these groups correspond with the A and D genomes, while the remainder ones were segregated from the species so far assigned to the B genome. This grouping is supported by the fertility data and by bivalent formation at meiosis in interspecific hybrids. which indicate that species from different  karyotype organization have a high reproductive isolation. Consequently, on the basis of these karyotypic groups we propose the existence of five different genomic types A, B, D, F and K for the species with 2n = 20 in the section.