Genomics approaches to analysis of genetic adaptation to climate in barley

Wild barley (Hordeum spontaneum) represents a significant genetic resource for crop improvement in barley (Hordeum vulgare) and for the study of the evolution and domestication of plant populations. Genomics tools are now available for analysis of large number of barley genes. We have developed, genotyping, SAGE and microarray tools for these analyses. However as a model example we have focused on a single gene, the Isa gene that has a putative role in plant defense. We found that this gene was expressed in the maternal tissues of the seed. We identified 16 Single Nucleotide Polymorphisms (SNPs) in the coding region of the Isa locus of 189 wild barley accessions from 8 sites that were characterized for 16 ecogeographical variables. The pattern of SNP suggested a large number of recombination events within this gene and 7 amino acid substitutions were present in the coding region. Highly significant correlations were found between diversity at the Isa locus and key water variables - evaporation, rainfall, humidity and latitude. The association is evident at both a local and regional level. These results are consistent with the possibility that inhibition of the plant’s own α-amylase by BASI may be a novel plant defense function. Study of the promoter and coding region of this gene indicate evolution of function at both levels.