Abstract
Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is the wild ancestor of all cultivated tetraploid and hexaploid wheats and harbors a large amount of genetic diversity. This diversity is expected to display eco-geographical patterns of variation, conflating gene flow, and local adaptation. As self-replicating entities comprising the bulk of genomic DNA in wheat, retrotransposons are expected to create predominantly neutral variation via their propagation. Here, we have examined the genetic diversity of 1 Turkish and 14 Israeli populations of wild emmer wheat, based on the retrotransposon marker methods IRAP and REMAP. The level of genetic diversity we detected was in agreement with previous studies that were performed with a variety of marker systems assaying genes and other genomic components. The genetic distances failed to correlate with the geographical distances, suggesting local selection on geographically widespread haplotypes (‘weak selection’). However, the proportion of polymorphic loci correlated with the population latitude, which may reflect the temperature and water availability cline. Genetic diversity correlated with longitude, the east being more montane. Principal component analyses on the marker data separated most of the populations.
Highlights
Wild emmer wheat (WEW), T. turgidum ssp. dicoccoides (Körn.) Thell., is the tetraploid progenitor of both cultivated tetraploid durum wheat and hexaploid common wheat
Screening for primers resulted in the selection of 15 LTR primer pairs for inter-retrotransposon amplified polymorphism (IRAP) and one primer pair for retrotransposon-microsatellite amplified polymorphism (REMAP) (LTR primer 738 with ISSR primer 443) (Figures 2 and 3)
The level of observed diversity was similar to that observed using RAPDs, the Retrotransposon marker techniques, here IRAP and REMAP, shed light on the genetic correlation was lowest of the marker methods
Summary
Wild emmer wheat (WEW), T. turgidum ssp. dicoccoides (Körn.) Thell., is the tetraploid progenitor of both cultivated tetraploid durum wheat and hexaploid common wheat. Retrotransposons remain a part of the chromosome and spread by producing daughter copies, which integrate at new loci, the precise insertion points of which are not likely to be used more than once These properties make retrotransposons well-suited as genetic markers. Given that plant retrotransposons are stress activated [13,17,18], their role in generating eco-geographical patterns of genomic diversity is of particular interest. Such patterns have been seen for example in wild barley [19] and wild diploid wheats [20,21] in Israel. We aimed to examine the adaptive nature of the pattern of retrotransposon integrations
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