Internode length in Pisum. Two further mutants, lh and ls, with reduced gibberellin synthesis, and a gibberellin insensitive mutant, lk

Three further internode length mutants in peas ( Pisum sativum L.), lh , ls and lk , were examined to determine if they influenced gibberellin synthesis or sensitivity. Two mutants, lh and ls , showed pronounced elongation in response to applied GA 1 and extracts from their shoots contained little gibberellin‐like activity when assayed on the rice seedling (cv. Tan ginbozu) bioassay compared with similar extracts from essentially isogenic Lh and Ls plants. The third mutant, lk , was almost insensitive to applied GA 1 and at no dose rate did it become a phenocopy of normal Lk plants. Extracts from the shoots of lk and Lk segregants contained similar levels of gibberellinlike substances. All three mutants influenced growth in both the light and the dark, although only the effect of genes Lh and Ls were graft transmissible. These results suggest that lh and ls are mutants with reduced gibberellin synthesis, while lk is the first gibberellin‐insensitive dwarfing gene identified in peas.