SEIJO Jose Guillermo
congresos y reuniones científicas
. Karyotype evolution of the genus Arachis.
ROBLEDO, G; SILVESTRI C; ORTIZ A; SAMOLUK, S; J. G. SEIJO; LAVIA G.I
Congreso; 9th International Conference of the Peanut Research Community on Advances in Arachis through Genomics and Biotechnology (AAGB-2017); 2017
International Peanut Genome Initiative
Arachis genus includes 81 autogamous and geocarpic species, all native from South America. Most of them are diploids with x=10, few (4) wlth x=9, and 5 are tetraploids with x=10. These species were arranged in 9 taxonomic sections and different genomes. Comparative studies by classical and molecular cytogenetics revealed large karyotype variability among species, however, there is still uncertainty concerning the major trends in the karyotype evolution of the genus. To shed light on this topic, we constructed a dataset with the available information on chromosome markers (45S and 5S rDNA and heterochromatin) and DNA content, which was further analyzed in a phylogenetic context based on ITS sequences. The results revealed that the ancestral species would have had low DNA content and karyotypes characterized by short chromosomes and absence or low content of heterochromatin C-DAPI+. The only general trend identified across the phylogeny was the increase of the genome size (Cx ). Other important features that arose from our results are 1) the A chromosomes' have arisen only once 2) the reduction of the basic chromosome number occurred in two independent linages, and 3) the polyploidization happened at least in three different events. Despite most of chromosome charactenstlc analyzed did not show a unidirectional tendency during evolutionary history, changes in the number of rDNA sites and in the patterns of DAPI heterochromatic distribution were related with the differentiation of genomic groups and some species.