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), differin g in their response to exogenously applied gibberellic acid (GA,), were map ped in the centromere region and on the long arm, respectively, of the barl ey chromosome 2H. The gene gal, which determines reduced plant height and G A insensitivity pleiotropically, was found to co-segregate with the two RFL P 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 t he three co-segregating RFLP markers Xmwg581, Xmwg882 and Xmwg2212 (proxima l) and XksuG5 (distal) by 3.6 and 9.5. cM, respectively. The distance betwe en the two mutant loci was estimated to be about 55 cM. Homoeologous relati onships between the dwarfing genes within the Triticeae are discussed.