Detection of seed dormancy QTL in multiple mapping populations derived from crosses involving novel barley germplasm

Seed dormancy is one of the most important traits in germination process to control malting and pre-harvest sprouting in barley (Hordeum vulgare L.). EST based linkage maps were constructed on seven recombinant inbred (RI) and one doubled haploid (DH) populations derived from crosses including eleven cultivated and one wild barley strains showing the wide range of seed dormancy levels. Seed dormancy of each RI and DH line was estimated from the germination percentage at 5 and 10 weeks post-harvest after-ripening periods in 2003 and 2005. Quantitative trait loci (QTLs) controlling seed dormancy were detected by the composite interval mapping procedure on the RI and DH populations. A total of 38 QTLs clustered around 11 regions were identified on the barley chromosomes except 2H among the eight populations. Several QTL regions detected in the present study were reported on similar positions in the previous QTL studies. The QTL on at the centromeric region of long arm of chromosome 5H was identified in all the RI and DH populations with the different degrees of dormancy depth and period. The responsible gene of the QTL might possess a large allelic variation among the cross combinations, or can be multiple genes located on the same region. The various loci and their different effects in dormancy found in the barley germplasm in the present study enable us to control the practical level of seed dormancy in barley breeding programs.