Genetic diversity in alfalfa (Medicago sativa L.) populations as revealed by retrotransposon based markers

Retrotransposons are common components of plantgenomes. Their abundance, dispersion, ubiquity andability to transpose make them good potential markers.In the current study, multilocus PCR-based techniques,IRAP and REMAP were used to detect integration eventsof retrotransposon families Tms1Ret1, LORE1, LORE2,Tps12a and Tps19 in Medicago sativa genome. IRAP andREMAP markers, derived from these retroelements, werealso used to study genetic diversity among and within80 tetraploid alfalfa genotypes from eight populations.Results indicated that retrotransposons Tms1Ret1,LORE1, LORE2 are present and transposoinionally activein M. sativa genome. A total of 101 and 119 loci wereamplified using 10 and 14 IRAP and REMAP primers,respectively. The number of polymorphic loci was 66 and62 for IRAP and REMAP, respectively. Populations weregrouped into three main clusters based on 128 IRAP andREMAP polymorphic loci. The genetic distance betweenpopulations ranged from 0.08 (Ghatayonjeh-Malekkandiand Turkey-Sakuel) to 0.134 (Azarbayejan-Ordubar andTurkey-Sakuel) with a mean value of 0.102. AMOVArevealed the higher level of genetic variation withinpopulations (92%) compared to among populations (8%),indicated no clear differentiation based on the studiedpopulations. Mean of hetrozygosity of population variedfrom 0.238 (Turkey-Sakuel) to 0.257 (Mahalie-Esfahaniand Turkey1), averaging 0.252. IRAP and REMAP-basedcluster analysis using complete linkage algorithm basedon Dice similarity coefficient identified five heteroticgroups in 80 alfalfa genotypes that could be applied asparents in M. sativa alfalfa breeding programs.

Keywords:

Tetra ploid alfalfa (Medicago sativa) , AMOVA , Tms1Ret1 Retrotransposon