| Abstract: | Among 16 dwarfing genes identified in wheat (Triticum aestiuvm L. em Thell.), four are known to be associated with insensitivity to the externally-supplied growth hormone gibberellin (GA). Rht1 and Rht2 (Reduced height 1 and 2, respectively) have been the most extensively used, because of their positive effect on yield. To increase the germplasm pool for dwarfism, a spring rye (Secale cereale) population (UC-90, CI-174) was selected because it contains high variability and any useful genes would benefit triticale and wheat as well. Seedlings of the CI-174 rye population were treated with 50 ppm of GA to identify any insensitive types. GA-insensitive and -sensitive seedlings were identified and, after three generations of selfing, GA-insensitive and -sensitive lines were fixed. Rye insensitive was crossed to a sensitive wheat and to rye and, reciprocally, insensitive wheat was crossed to sensitive rye. The results indicated that a GA-insensitivity dwarfism system similar to that originally found in wheat also operates in rye and appears to be under simple inheritance. Rye GA-insensitivity was expressed in triticale. Therefore, it is possible to transfer this new source of insensitivity and dwarfism into triticale and wheat. |
