Cloning of the Gene Laxatum (lax.a) - Prospects from an Improving Barley Genomics Infrastructure

The barley mutant laxatum.a (lax.a) displays a set of pleiotropic phenotypic characteristics compared to the wild type: (i) increased spike length due to extended rachis internodes, (ii) awns with a very wide base, (iii) thin and exposed grains, (iv) as well as a homeotic conversion of the lodicules into two additional anthers. High resolution mapping in ~2000 F2 plants delimited the gene locus to a 0,2 cM target interval in a region which is characterized by reduced recombination. Thus, a large physical distance that comprises up to 200 genes required further mapping effort. On the basis of advanced genomic resources (IBSC, 2012) our aim was to test an adapted version of cloning-by-sequencing method in barley. By combining whole-genome-shotgun sequencing (WGS) data of the parental genotypes, RNA-seq data of phenotypic pools as well as exome capture (Mascher et al. 2013) re-sequencing of genetically closely linked lax.a recombinant plants a single candidate gene could be identified for lax.a. These results proof the feasibility of adapting high-throughput sequencing methodology for gene isolation in barley.

References:   IBSC (2012), Nature 491, 711-716;  Mascher et al (2013) Plant Journal 76;  doi: 10.1111/tpj.12294