Retroelements of Arachis duranensis (AA) and A. ipaënsis (BB) Genomes and their Distribution in Peanut Chromosomes

Repetitive elements such as retrotransposons usually bring ambiguity during DNA sequences alignments, but it is clear that they are actively involved in the organization and evolution of these genomes. Identification and annotation of retrotransposons is of fundamental importance to the understanding of genomes structure, function and evolution, especially for A. duranensis and A. ipaënsis, whose complete genome sequences are now on the verge of being, accomplished (IPGI). Therefore, a large sequence data set using computational tools are under way to identify and characterize retrotransposons in the last assembled genome sequences of these species, the pioneer work involving comparative analysis of LTR retrotransposons in the peanut AA and BB genomes. Initial analysis of A. ipaënsis genome sequence revealed 79 new families of LTR retrotransposons distributed in 24 families of non- and 65 autonomous families. Throughout the comparison with the complete LTR retrotransposons sequences identified in A. ipaënsis, 81 families, classified in 23 families of non-autonomous and 58 autonomous LTR retrotransposons were identified. These LTR retrotransposons and their fragments engaged around 28.5 and 27.6% of these genomes respectively, with 37 families representing the major part. Initial analysis of fluorescent in situ hybridization (FISH), using as probes sequences typical of each retrotransposons family identified, showed multiple and disperse signals in some, mostly at pericentromeric regions, but not all of the metaphase chromosomes of A and B genomes of A. hypogaea. Further preliminary in silico analysis indicated that elements were mostly found in the centromere region, whilst others were found at distal regions of chromosomes.