The Identification of a Gibberellic‐Acid‐Insensitive Gene in Secale cereale*

Abstract

AbstractAmong 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.