Expression of gibberellin mutations in fruits of Pisum sativum L.

Abstract.

The gibberellin (GA) economy of young pea (Pisum sativum L.) fruits was investigated using a range of mutants with altered GA biosynthesis or deactivation. The synthesis mutation lh-2 substantially reduced the content of both GA₄ and GA₁ in young seeds. Among the other synthesis mutations, ls-1, le-1 and le-3, the largest reduction in seed GA₁ content was only 1.7-fold (le-1), while GA₄ was not reduced in these mutants, and in fact accumulated in some experiments (compared with the wild type). Mutation sln appeared to block the step GA₂₀ to GA₂₉ in young pods and seeds, but not as strongly as in older seeds. Mutations ls-1, le-1 and le-3 markedly reduced pod GA₁ levels, but pod elongation was not affected. After feeds of [¹³C,³H]GA₂₀ to leaves, the pods contained ¹³C,³H-labelled GA₂₀, GA₁, GA₂₉ and GA₈₁, and the seeds, [¹³C,³H]GA₂₀ and [¹³C,³H]GA₂₉. These findings are discussed in relation to recent suggestions regarding the role and origin of GA₁ in pea fruits.