Microsatellite diversity correlated with ecological-edaphic and genetic factors in three microsites of wild emmer wheat in North Israel

This study was conducted to test the effects of internal (genetic) and exte rnal factors on allelic diversity at 27 dinucleotide microsatellite (simple sequence repeat [SSR]) loci in three Israeli natural populations of Tritic um dicoccoides from Ammiad, Tabigha, and Yehudiyya, north of the Sea of Gal ilee. The results demonstrated that SSR diversity is correlated with the in teraction of ecological and genetic factors. Genetic factors, including gen ome (A vs. B), chromosome, motif, and locus, affected average repeat number (ARN), variance in repeat number (sigma(2)), and number of alleles (NA) of SSRs, but the significance of some factors varied among populations. Genom e effect on SSR variation may result from different motif types, particular ly compound (or imperfect) versus perfect motifs, which may be related to d ifferent evolutionary histories of genomes A and B. Ecological factors sign ificantly affected SSR variation. Soil-unique and soil-specific alleles wer e found in two edaphic groups dwelling on terra rossa and basalt soils acro ss macro- and microgeographical scales. The largest contributions of geneti c and ecological effects were found for diversity of ARN and NA, respective ly. Multiple regression indicated that replication slippage and unequal cro ssing over could be important mutational mechanisms, but their significance varied among motifs. Edaphic stresses may affect the probability of replic ation errors and recombination intermediates and thus control diversity lev el and divergence of SSRs. The results may indicate that SSR diversity is a daptive, channeled by natural selection and influenced by both internal and external factors and their interactions.