Karyotype evidences of genome differentiation at diploid and polyploid levels in Arachis species (sect. Arachis)

J. G. SEIJO; SAMOLUK, S; CHALUP, L.; ROBLEDO, G

Montevideo

Congreso; Congreso; XVI Congreso Latinoamericano de Genética. IV Congreso de la Sociedad Uruguaya de Genética. XLIX Reunión Anual de la Sociedad de Genética de Chile. XLV Congreso Argentino de Genética; 2016

Título:Karyotype evidences of genome differentiation at diploid and polyploid levels in Arachis species (sect. Arachis)Autor/es:SEIJO, GUILLERMO; SAMOLUK, SEBASTIÁN; CHALUP, LAURA; ROBLEDO, GERMÁNLugar:MontevideoReunión:Congreso; XVI Congreso Latinoamericano de Genética. IV Congreso de la Sociedad Uruguaya de Genética. XLIX Reunión Anual de la Sociedad de Genética de Chile. XLV Congreso Argentino de Genética.; 2016Resumen:Section Arachis is composed of diploid species (2n=20, 18) with A, B, D, F, G or K genomes and two AABB tetraploids, the peanut and its direct antecessor A. monticola. In this study, the role of the repetitive fraction in the differentiation of the genomes at diploid and polyploid levels was investigated. For that purpose, different repetitive sequences were isolated (PCR), characterized (sequence analysis), quantified (dot blot) and chromosome mapped (FISH) in representative species of each genome. Additionally, the global pattern of 5-methylcytosine was analyzed by immunocytochemistry. The retroelements Ty3-Gypsy and LINES, the CACTA-like transposons, and the TR2 satellite sequence were differentially represented and distributed on the chromosomes of the species belonging to different genomes. The distribution pattern of the 5-methylcytosine was distinctive between the A and B genomes. All the markers analyzed in the allotetraploids evidenced the sum of the patterns observed in their diploid progenitors. However, the cytosines of the B-genome of the tetraploids appeared hypermethylated with respect to its wild progenitor and nucleolar dominance of the A genome was observed in the polyploid taxa. These results evidenced that changes in the repetitive fraction and in the epigenetic patterns had played a key role in the genome differentiation at diploid level. However, the allopolyploidization did not affect the gross chromosome structure in the AABB taxa, but triggered a massive hypermethylation of the B genome.