There is considerable interest and energy expended on attempting to understand and improve drought tolerance in barley. Discovery of the genes controlling this trait would greatly improve our understanding of this complex phenotype and aid in the development of more tolerant varieties (picture right; wild barley growing in Israel).

Our approach is to combine three unique barley resources; a segregation population of 140 barley lines composed of an advanced elite genetic background containing introduced chromosomal segments from a wild barley accession from the Fertile Crescent, adapted and tolerant of drought and salt stresses (RCSLs see Matus and Hayes 2003); a collection of 480 lines (Syrian Jordanian Landrace collection- SJLC), sampled from a large barley collection (Ceccarelli et al., 1987) chosen from five geographical regions representing South Jordan, North Jordan-South Syria, West Syria, Central Syria and North-East Syria; and a high throughput SNP genotyping platform for barley based on the Illumina GoldenGate and Oligo Pool Assays (OPA) (Oliphant et al., 2002, Fan et al., 2003).

Figure: Landrace barley grown at ICARDA in Syria

By combining genotyping with relevant phenotypic information on the RCSLs, we will be able to identify segments of the donor genome that confer drought tolerance and morphological variation. Once we have identified specific target regions of this sample of the H. spontaneum genome that confer increased drought tolerance. We will then pursue the parallel objectives of regionally resequencing alleles to develop markers for further haplotype analysis and phenotypic association studies in a set of 340 lines from the Syrian and Jordanian Landrace Collection (SJLC).

These lines, sampled from a gradient of agroecological conditions, showed a wide range of responses to drought stress as established by extensive field trials.  Using new genotypic data from the Illumina Oligo Pool Assay (OPA) platform and the available phenotypic data for the SJLC, we will investigate the use of whole genome association scans to identify and validate genes and markers linked to performance under drought stress. Finally we will initiate the process of validating diverse alleles (more probably linked ‘regional haplotypes’) by introgressing them into a common genetic background.