Molecular mapping of two dwarfing genes differing in their GA response on chromosome 2H of barley.

The two recessive dwarfing mutants gai (GA-ins) and gal (GA-less), differing in their response to exogenously applied gibberellic acid (GA(3)), were mapped in the centromere region and on the long arm, respectively, of the barley chromosome 2H. The gene gai, which determines reduced plant height and GA insensitivity pleiotropically, was found to co-segregate with the two RFLP markers Xmwg2058 and Xmwg2287. Both markers are known to map close to the centromere. The GA-sensitive dwarfing gene gal was found to be linked to the three co-segregating RFLP markers Xmwg581, Xmwg882 and Xmwg2212 (proximal) and XksuG5 (distal) by 3.6 and 9.5. cM, respectively. The distance between the two mutant loci was estimated to be about 55 cM. Homoeologous relationships between the dwarfing genes within the Triticeae are discussed.