SEIJO Jose Guillermo
congresos y reuniones científicas
A-TR2, a satellite sequence of the centromeric heterochromatin of A. duranensis.
ROBLEDO, G; BERTIOLI, D.J; J. G. SEIJO
Congreso; 5th International Conference of the Peanut Research Community on Advances in Arachis through Genomics and Biotechnology (AAGB).; 2011
A-TR2, a satellite sequence of the centromeric heterochromatin of A duranensis. Robledo, G*, D. Bertioli and G. Seijo Highly repetitive DNA sequences are main components of eucaryotes genomes. Different types of these sequences may coexist within a particular genome and it was proposed that changes in their composition and representation actively participate in the genomic differentiation of plants. Sections Arachis comprise 29 wild diploid species and two allopolyploid (A. hypogaea n.v. peanut and A. monticola) which were arranged in five different genomes (A, B, D, F y K). Recent analysis of molecular markers suggested an extensive colinearity among some of these genomes, while GISH experiments suggest a marked difference in the repetitive component of them. For this reason, we focused on the repetitive fraction of Arachis species, particularly in the tandemly repeated sequences. In this work, we isolated and characterized a repeated sequence, A-TR2, present in the genomes of A. duranensis. The length of the basic repeated units ranges from 308 to 324 bp, and form tandem arrays in 91 GSS of the public databases. The detailed analysis of these sequences revealed a high content of AT bases (82 to 84 %) and the presence of several motifs involved in the dispersion and chromatin packaging mechanisms of tandemly repeated sequences. Moreover, the results obtained by FISH indicate that this sequence is one of the main components of the centromeric C-DAPI+ blocks in at least five chromosome pairs of A. duranensis. Thus, the data on nucleotide composition, organization and chromosomal distribution evidence that A-TR2 is a typical centromeric satellite DNA sequence, the first described for Arachis genomes.