Variation in chloroplast microsatellite loci among wild and cultivated species of Emmer wheat

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It is generally accepted that cultivated Emmer wheat (Triticum dicoccum Schubl.) originated from its wild ancestor (T.dicoccoides Korn.) by domestication about eight thousand years ago, somewhere in the Fertile Crescent. To study the origin of the cultivated Emmer wheat, allelic diversity in eight microsatellite loci of the chloroplast genome was investigated using 100 accessions of T.dicoccum and 72 accessions of T.dicoccoides. Five accessions of=T.paleocolchicum Men., two of T.durum L.and one each of T.aestivum L., T.carthlicum Nevski, T.ispahanicum Heslot, T.polonicum L.and T.turgidum L.were analyzed as references. The number of repeats in each locus was determined using PCR followed by PAGE.Polymorphic band patterns were obtained at seven out of the eight loci. As for the polymorphic microsatellites, the number of alleles per locus ranged from two to five with an average of 2.92. Nei's allelic diversity was estimated for each locus within each species. The average allelic diversity of T.dicoccoides (0.349) was about 3.2 times larger than that of T.dicoccum (0.109). One plastotype representing 80 % of the T.dicoccum accession and all accessions of references was identical to that of T.aestivum cv Chinese Spring. Whereas this major plastotype of the cultivated wheat was identified only in six T.dicoccoides accessions collected in one region in the north western Fertile Crescent. In addition to this major maternal lineage, we have identified a minor lineage from the wild Emmer to the cultivated Emmer wheat. These results suggest that there are at least two maternal lineages in cultivated Emmer wheat, and that the domestication of Emmer wheat with the major plastotype occurred in the north western Fertile Crescent.