A Barley Root Mutants Collection for Fast Forward Genetics

Despite the importance of mutants in plant biology investigations and breeding, only a limited number of root mutants have been described in crop species, and the number and nature of genes involved in root traits remain largely unknown. We are performing a forward-genetics screening of a barley mutagenized population formerly produced for TILLING purposes (cv. Morex background. Talamè et al. 2008, Plant Biotechnol J. 6:477-485) to identify root morphology mutants by means of a paper(cigar)-roll method. We have already analyzed >3,000 M5 mutant families at the seedling stage and several tens of root mutants have been identified and confirmed by three replications. The mutants were grouped in three categories: root growth rate/length (short and long, 77%), root morphology (coiling, geotropic, etc., 15%) and root hairs (hairless, shorthairs, etc., 8%). Randomly chosen mutants were utilized in experimental crosses and their Mendelian inheritance was confirmed. As a first step towards mapping and cloning the loci responsible of the observed mutant phenotypes, a SNP array (Illumina Barley 9K)-based bulk-segregant analysis was applied and shown to enable quickly and inexpensive mapping at cM-range interval. Additional NGS-based approaches are being tested in order to streamline the process linking a mutant with the underlying gene, thus making our population a generally useful resource for functional genomics in cereals.