Abstract
BackgroundThe increasingly narrow genetic background characteristic of modern crop germplasm presents a challenge for the breeding of cultivars that require adaptation to the anticipated change in climate. Thus, high priority research aims at the identification of relevant allelic variation present both in the crop itself as well as in its progenitors. This study is based on the characterization of genetic variation in barley, with a view to enhancing its response to terminal drought stress.ResultsThe expression patterns of drought regulated genes were monitored during plant ontogeny, mapped and the location of these genes was incorporated into a comprehensive barley SNP linkage map. Haplotypes within a set of 17 starch biosynthesis/degradation genes were defined, and a particularly high level of haplotype variation was uncovered in the genes encoding sucrose synthase (types I and II) and starch synthase. The ability of a panel of 50 barley accessions to maintain grain starch content under terminal drought conditions was explored.ConclusionThe linkage/expression map is an informative resource in the context of characterizing the response of barley to drought stress. The high level of haplotype variation among starch biosynthesis/degradation genes in the progenitors of cultivated barley shows that domestication and breeding have greatly eroded their allelic diversity in current elite cultivars. Prospective association analysis based on core drought-regulated genes may simplify the process of identifying favourable alleles, and help to understand the genetic basis of the response to terminal drought.
Highlights
The increasingly narrow genetic background characteristic of modern crop germplasm presents a challenge for the breeding of cultivars that require adaptation to the anticipated change in climate
We report haplotyping data for 17 starch biosynthesis/ degradation genes demonstrating the broad diversity among H. spontaneum accessions and H. vulgare landraces but rather limited genetic variance in the current elite breeding germplasm by fixing certain haplotypes
An extensive expression analysis of these ESTs at various developmental stages for drought response and across a range of barley accessions resulted in creating an expression map for genetically mapped markers
Summary
The increasingly narrow genetic background characteristic of modern crop germplasm presents a challenge for the breeding of cultivars that require adaptation to the anticipated change in climate. Of all the genetic marker types available, single nucleotide polymorphisms (SNPs) are the most abundant, and offer the greatest level of genetic resolution. They are of potential functional relevance and they are well suited to high throughput analytical methods [7]. We present a SNP-based genetic map of barley, focussing on nucleotide variation in ESTs demonstrated to be involved in the response of barley to drought stress occurring at early vegetative stages, during anthesis and the grain filling process
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