SAMOLUK Sergio Sebastian
First insight into divergence, representation and chromosome distribution of reverse transcriptase fragments from L1 retrotransposons in peanut and wild relative species
SAMOLUK S.; ROBLEDO G.; PODIO M.; CHALUP L.; ORTÍZ J. P. A.; PESSINO S. C.; SEIJO G.
Peanut is an allotetraploid (2n = 2x = 40,AABB) of recent origin. Arachis duranensis and A. ipae¨nsis, the most probable diploid ancestors of the cultigen,and several other wild diploid species with different genomes(A, B, D, F and K) are used in peanut breedingprograms. However, the genomic relationships and theevolutionary pathways of genome differentiation of thesespecies are poorly understood. We performed a sequencebasedphylogenetic analysis of the L1 reverse transcriptaseand estimated its representation and chromosome distributionin species of five genomes and three karyotypegroups with the aim of contributing to the knowledge of thegenomic structure and evolution of peanut and wild diploidrelatives. All the isolated rt fragments were found tobelong to plant L1 lineage and were named ALI. The bestsupported phylogenetic groups were not concordant withthe genomes or karyotype groups. The copy number of ALIsequences was higher than the expected one for plants anddirectly related to genome size. FISH experiments revealedthat ALI is mainly located on the euchromatin of interstitialand distal regions of most chromosome arms. Divergenceof ALI sequences would have occurred before the differentiationof the genomes and karyotype groups of Arachis.The representation and chromosome distribution of ALI inpeanut was almost additive of those of the parental speciessuggesting that the spontaneous hybridization of the twoparental species of peanut followed by chromosome doublingwould not have induced a significant burst of ALItransposition.