Feed-forward regulation of gibberellin deactivation in pea

Multiple lines of evidence suggest that the genes involved in gibberellin ( GA biosynthesis are regulated by bioactive GA levels. With the recent cloni ng of GA 2-oxidase genes from pea, we investigated whether this homeostatic regulation extends to the genes controlling GA deactivation in this specie s, utilizing two well-characterized GA-deficient mutants, ls and na and a G A-accumulating mutant, sln. The pea GA 2-oxidases showed feed-forward effec ts at the mRNA level, while the endogenous levels of GA(20), GA(29), GA(1), and GA(8) showed no evidence of feed-forward regulation. Analyses of genom ic Southern blots and expressed sequenced tag (EST) databases suggest that other GA 2-oxidases could possibly account for this lack of feed-forward on GA levels.