SEIJO Jose Guillermo
congresos y reuniones científicas
Karyotype and DNA content patterns of the genus Arachis in a phylogenetic context
SILVESTRI C; A. ORTIZ; ROBLEDO, G; J. G. SEIJO; G.I. LAVIA
Congreso; 21st International Chromosome Conference; 2016; 2016
Título:Karyotype and DNA content patterns of the genus Arachis in a phylogenetic contextAutor/es:SILVESTRI, MARÍA C.; ORTIZ, ALEJANDRA M.; ROBLEDO, GERMÁN; SAMOLUK, SEBASTIÁN; SEIJO, GUILLERMO; LAVIA, GRACIELA I.Lugar:Foz do IguaçuReunión:Conferencia; 21st International Chromosome Conference; 2016Resumen:Arachis is a South American genus that includes 82 autogamous and geocarpic species. Most species are diploids with x = 10, 4 are diploids with x = 9, and 5 are tetraploids with x = 10. Based on morphology and cross-compatibility, these species were arranged in 9 sections and different genomes. Classical and molecular cytogenetics revealed large karyotype variability among species and has also been very important for the infrageneric arrangement of the genus. The objective of this research was to make inferences about the direction of changes in different chromosome markers and DNA content during the evolution of the genus. For this purpose, new cytogenetic (FISH with 45S and 5S rDNA and heterochromatic markers) and DNA content (flow cytometry estimated 2C values) data, together with those available, were analyzed in a phylogenetic context based on (available and new data) ITS sequences. This analysis revealed that in the evolutionary history of the genus: (1) there is a general tendency of a genome size (Cx) increase, although independent reductions occurred more than once, (2) reduction of the basic chromosome number (from x = 10 to x = 9) occurred twice, (3) polyploidization based on x = 10 occurred more than once, (4) ?A chromosomes? originated only once, (5) different patterns of DAPI/CMA heterochromatic bands were observed in 2 (out of 3) of the main clades, and (6) the number of 5S rDNA loci is generally 1 pair (exceptions are found in different clades), while the number of 45S rDNA is more variable (1?5 pairs). Most of the chromosome characters analyzed according to the ITS phylogenetic hypothesis for genus Arachis did not show a unidirectional evolutionary history.