The Metabolism of cis ABA-aldehyde by the Wilty Mutants of Potato, Pea and Arabidopsis thaliana

RS-²H₁] cis ABA-aldehyde was fed to ABA-deficient mutants ofpotato (droopy), pea (wilty) and Arabidopsis thaliana (aba¹)along with appropriate non-mutant controls. Both the wilty andaba¹ mutants readily oxidized the monodeuterated ABA-aldehydeto ABA. The incorporation of label into ABA by these two mutantswas indistinguishable from that detected in the non-mutant controls.In contrast, the droopy mutants poorly incorporated the labelledprecursor into ABA. Instead they reduced and isomerized RS-²H₁] cis ABA-aldehyde to a mixture of 2, cis and 2, trans ABA-alcohols.Thus the droopy mutant affects the last step in ABA biosynthesis,a position it shares with the tomato mutants, flacca and sitiens.Genetic evidence suggesting that droopy and sitiens may be correspondinggene loci is discussed. Key words: ABA metabolism, wilty mutants, pea, potato, Arabidopsis