The genetic potential of Wild Barley (Hordeum spontaneum C. Koch) to Improve Adatation to low rainfall environments.

The main objective of this study was to examine the contribution of wild bareley to the improved adaptation of germplasm developed by the ICARDA breeding program.The project amins to identify chromosomal regions associated with drought tolerance and identify simple sequence repeats and single nucleotide polymorphism markers for selection of genomic regions conferring improved adaptation to low rain fall environments through graphical genotyping and LD based assocation mapping.A field experiment conducted on 57 barley lines carring various levels of introgression from Hordeum vulgare ssp.spontaneum and 14 barley drought populations with contrasting response to drought stress showed a considerable amount of genetic variability among the genotypes for the various agromnomic and developmental traits measured in a range of Mediterranean thousand-kernel weight were important for yield improvement in the dry environments. Results from the greenhouse study showed that genotypes differed sinigicantly for osmotic adjustment, relative water content,chlorophyll conten, peduncle length,peduncle extrusion,spike length, plant height, total tiller number and fertile tiller number.Molecular analysis was performed using 74 SSR and 20 SNP markers for the analysis of graphical genotyping and LD based association mapping on the 57 introgression lines and marker-trait correlations on the 14 drought populations using 50 SSR markers.The graphical genotyping analysis showed that the average length of donor chromosome segements of Hordeum vulgare ssp. spontaneum ranged between 20.4 and 45.4 cM for chromosomes 1H to 7H, with an overall agverage donor trait associations for grain yield and drought realted traits.A total fo 72 (49%) marker-trait associations showed favorable effects of the exotic germaplasm where the Hordeum vulgare ssp. spontaneum lines contributed to an improvement of the trait under drought stress conditions.The effect of vernalization and photoperiod responses was determined on 90 diverse barley genotypes.The results revealed that genotypes with Hordeum vulgare ssp.spontaneum background exhibited wide variation for vernalization and photoperiod responses while improved varieties from Australia and Ethiopia showed a narrow range of response to vernalization in both short-day and long-day photoperiods.The present study indicates that a combination of field, greenhouse and molecular studies could help in understanding the genetic mechanisms of drought tolerance in barley.