Natural and Induced Mutants of Barley: Single Nucleotide Polymorphisms in Genes Important for Breeding

Much mutation research has been conducted on barley and many different morphological mutant classes have been identified, often with multiple loci and alleles at each locus. Barley mutants have influenced not only genetic research, but also the development of commercially significant varieties. Several important cultivars that were the direct products of mutation programs have been released, notably Pallas and Golden Promise. Many current European spring barley cultivars are the indirect results of induced mutation programs due to the widespread deployment of the sdw1 dwarfing gene. The development of a high-throughput system to assay single nucleotide polymorphisms (SNPs) in the mapped barley gene is resulting in the identification of candidate loci affecting a range of barley mutant characters. Where a known mutation is fairly frequent in a population, SNP genotyping can be combined with classification of the phenotype to identify a clearly defined region of the barley genome affecting the character. Bioinformatics approaches can then be utilized to identify syntenic regions of the rice genome and a list of potential candidate genes. We demonstrate how this approach can be deployed using either association genetics or graphical genotyping to localize candidate regions containing vrs1 affecting the two/six-row phenotype or rym4/5 affecting virus resistance, respectively.