Genetic diversity in populations of wild diploid wheat Triticum urartu Tum. ex. Gandil. revealed by isozyme markers

Genetic variation and its distribution within and among 23 populations of T riticum urartu collected from Syria, Lebanon, Turkey, Armenia, and Iran was estimated using isozyme markers at eight polymorphic loci. The number of a lleles per locus (A= 1.21), percentage polymorphic loci (P= 20.1%), and mea n gene diversity (H-e= 0.024) were relatively low. In a population from Leb anon, a high number of alleles per locus (A= 2.13) and percentage polymorph ic loci (P= 87.5%) was found. On average, genetic variation among populatio ns (G(ST)= 0.407) was smaller than within-population variation (0.593). How ever, different patterns of genetic structure were found among various geog raphic regions. Interpopulation variation was highest for the Iranian popul ations (0.89) followed by the Turkish populations (0.66). A reverse pattern was observed for the Syrian (0.11) and for the Lebanese (0.13) populations . The Armenian populations exhibited similar interpopulation and within-pop ulation variation. Principal component and cluster analyses resulted in dis tinct grouping of the geographically proximal populations, with the excepti on of the two Iranian populations. The Turkish populations were different f rom the neighboring Armenian populations compared to other countries. The p opulations from southern Syria and those from Lebanon also exhibited a high degree of genetic diversity. The two most heterozygous loci, Mdh-2 and Pgi -2, separated the populations along the first and second principal componen ts, respectively. Most of the rare alleles were scattered sporadically thro ughout the geographic regions. Rare alleles with high frequencies were foun d in the Turkish and Armenian populations. These results indicated that dif ferent geographic regions require specific sampling procedures in order to capture the range of genetic variation observed in T. urartu populations.