Adaptive microclimatic evolution of the dehydrin 6 gene in wild barley at “Evolution Canyon”, Israel

Abstract

Dehydrins are one of the major stress-induced gene families, and the expression of dehydrin 6 (Dhn6) is strictly related to drought in barley. In order to investigate how the evolution of the Dhn6 gene is associated with adaptation to environmental changes, we examined 48 genotypes of wild barley, Hordeum spontaneum, from "Evolution Canyon" at Mount Carmel, Israel. The Dhn6 sequences of the 48 genotypes were identified, and a recent insertion of 342 bp at 5'UTR was found in the sequences of 11 genotypes. Both nucleotide and haplotype diversity of single nucleotide polymorphism in Dhn6 coding regions were higher on the AS ("African" slope or dry slope) than on the ES ("European" slope or humid slope), and the applied Tajima D and Fu-Li test rejected neutrality of SNP diversity. Expression analysis indicated that the 342 bp insertion at 5'UTR was associated with the earlier up-regulation of Dhn6 after dehydration. The genetic divergence of amino acids sequences indicated significant positive selection of Dhn6 among the wild barley populations. The diversity of Dhn6 in microclimatic divergence slopes suggested that Dhn6 has been subjected to natural selection and adaptively associated with drought resistance of wild barley at "Evolution Canyon".

Evolution of wild barley at “Evolution Canyon”: adaptation, speciation, pre-agricultural collection, and barley improvement

“…Similar results were unfolded in our analysis of Dehydrin 6 (Dhn6) (Yang et al 2012) and small Heat Shock Proteins, sHSP (Zhang et al 2014). Natural microclimatic selection appears to adaptively diversify the duplicated copies of hsp 17 of wild barley between the opposite warmer and cooler slopes, suggesting that the recent duplication of stress-responsive genes was subjected to adaptive evolution.…”

SNP-revealed genetic diversity in wild emmer wheat correlates with ecological factors

“…These results suggested that the operation of natural selection and the adaptive nature of genetic variation could be explained by the variation of ecological factors. The sharp regional gradient of climatic conditions from north to south in Israel, with increasing temperatures and decreasing water availability towards the semiarid zones in southern Israel play a major role as do microecological climatic and edaphic stresses [16,52]. That is also why latitude was found to be associated with frequency variation for most SNP allele (Additional file 3: Table S2).…”

Adaptive evolution of duplicated hsp17 genes in wild barley from microclimatically divergent sites of Israel

“…Comparing the recent studies of the stress-induced genes Dhn1 (Yang et al, 2009) and Dhn6 (Yang et al, 2011), hsp17 has higher divergences, while the disease resistance-related gene Isa had fewer polymorphisms (Cronin et al, 2007). The ECI model provides clues to future evolutionary studies on both stress genes and speciation genes.…”