Adaptive Genetic Differentiation and Solar Radiation in Wild Emmer Wheat, Triticum dicoccoides.

Background: Microgeographic studies of molecular markers could reveal the nature and dynamics of genetic diversity and the evolutionary driving forces shaping evolution.

Methods: The microclimatic genetic divergence of wild emmer wheat associated with solar radiation was investigated, in the present study, using multiple types of molecular markers including allozyme, amplified polymorphic DNA (RAPD), simple sequence repeat (SSR), and single nucleotide polymorphisms (SNP). The studies included two climatic microniches: (1) sunny between oak trees; and (2) shady under the canopies of oak trees.

Results: All four types of markers showed a similar microniche tendency of genetic variance, i.e., lower in the shady than in the sunny niche. Significant genetic divergence at some loci including allozyme, RAPD, SSR, and SNP was detected between the two climatic microniches, and also, the observed genetic differentiation is mainly due to natural selection. Based on different FST outlier detection algorithms, there were 21 candidate loci subjected to positive selection. Importantly, most of the identified candidate loci were mapped in the selection "hot spots" of wheat genome.

Conclusion: The present work implies that microclimatic selection appears to play an important role either in the protein-coding region or in the non-coding region of wheat genomes, and hence, highlights the evolutionary theory of natural selection.