title: Evolutionary dynamics of an at-rich satellite DNA and its contribution to karyotype differentiation in wild diploid Arachis species.
abstract: Satellite DNA (satDNA) is a major component of the heterochromatic regions of eukaryote genomes and usually shows a high evolutionary dynamic, even among closely related species. Section Arachis (genus Arachis) is composed of species belonging to six different genomes (A, B, D, F, G and K). The most distinguishing features among these genomes are the amount and distribution of the heterochromatin in the karyotypes. With the objective of gaining insight into the sequence composition and evolutionary dynamics of the heterochromatin fraction in Arachis, we investigated here the sequence diversity, genomic abundance, and chromosomal distribution of a satDNA family (ATR-2) among seven diploid species of section Arachis. All of the isolated sequences were AT-rich and highly conserved at both intraspecific and interspecific levels, without any species-specific polymorphism. Pairwise comparisons of isolated ATR-2 monomers revealed that most of the nucleotide sites were in the first two transitional stages of Strachan's model. However, the abundance of ATR-2 was significantly different among genomes according to the 'library hypothesis'. Fluorescent in situ hybridization revealed that ATR-2 is a main component of the DAPI+centromeric heterochromatin of the A, F, and K genomes. Thus, the evolution of the different heterochromatin patterns observed in Arachis genomes can be explained, at least in part, by the differential representation of ATR-2 among the different species or even among the chromosomes of the same complement. These findings are the first to demonstrate the participation of satDNA sequences in the karyotype diversification of wild diploid Arachis species.
authors.affiliation: Facultad de Ciencias Agrarias, Instituto de Botánica del Nordeste (UNNE-CONICET), Casilla de Correo 209, 3400, Corrientes, Argentina. ssamoluk@agr.unne.edu.ar.
authors.forename: Sergio Sebastián
authors.initials: SS
authors.lastname: Samoluk
authors.affiliation: Facultad de Ciencias Agrarias, Instituto de Botánica del Nordeste (UNNE-CONICET), Casilla de Correo 209, 3400, Corrientes, Argentina.|Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Av. Libertad 5460, 3400, Corrientes, Argentina.
authors.forename: Germán
authors.initials: G
authors.lastname: Robledo
authors.affiliation: Universidade de Brasília, Campus Universitário, 70910-900, Brasília, DF, Brazil.|Center for Applied Genetic Technologies, University of Georgia, Athens, GA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Bertioli
authors.affiliation: Facultad de Ciencias Agrarias, Instituto de Botánica del Nordeste (UNNE-CONICET), Casilla de Correo 209, 3400, Corrientes, Argentina.|Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Av. Libertad 5460, 3400, Corrientes, Argentina.
authors.forename: José Guillermo
authors.initials: JG
authors.lastname: Seijo
mesh_terms: D000465:Algorithms; D010367:Arachis / Q000235:genetics*; D002454:Cell Differentiation; D003001:Cloning, Molecular; D019295:Computational Biology; D018744:DNA, Plant / Q000235:genetics; D004276:DNA, Satellite / Q000235:genetics*; D004171:Diploidy; D019143:Evolution, Molecular; D014644:Genetic Variation; D018745:Genome, Plant; D006570:Heterochromatin / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D059785:Karyotype; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D018744:DNA, Plant; D004276:DNA, Satellite; D006570:Heterochromatin
keywords: Arachis species; Heterochromatin; Karyotype differentiation; Library hypothesis; Satellite DNA