First insight into divergence, representation and chromosome distribution of reverse transcriptase fragments from L1 retrotransposons in peanut and wild relative species.

SAMOLUK, S; M. PODIO; CHALUP, L.; ROBLEDO, G; J.P.A. ORTIZ; S.C. PESSINO; J. G. SEIJO

GENETICA

SPRINGER

Lugar: Berlin; Año: 2015 vol. 143 p. 113 - 125

0016-6707

Peanut is an allotetraploid (2n = 2x = 40, AABB) of recent origin. Arachis duranensis and A. ipaënsis, the most probable diploid ancestors of the cultigen, and several other wild diploid species with different genomes (A, B, D, F and K) are been used in peanut breeding programs. However, the genomic relationships and the evolutionary pathways of genome differentiation of these species are poorly understood. To learn more about the genomic structure and evolution of peanut and wild diploid relatives, we produced a L1 reverse transcriptase sequence-based phylogenetic analysis and estimated their representation and chromosome distribution in species representative of five genomes and three karyotype groups. All the rt fragments of LINEs isolated belong to the plant L1 lineage and were named ALI. The best supported phylogenetic groups were not concordant with the genomes or karyotype groups. ALI sequences were detected in higher copy number than the expected one for plants and the variation in representation was directly related to the genome size. FISH experiments revealed that ALI is mainly located on the euchromatine of interstitial and distal regions of most chromosome arms in all the analyzed species. We concluded that the divergence of ALI sequences occurred before the differentiation of the genomes and karyotype groups of Arachis section. The representation and chromosome distribution of ALI in peanut was almost additive of those of the parental species. Our study suggests that the spontaneous hybridization of the two parental species of peanut followed by chromosome doubling did not induce a significant burst of ALI transposition.