Azospirillum spp. metabolize [17,17-2H2]gibberellin A20 to [17,17-2H2]gibberellin A1 in vivo in dy rice mutant seedlings

Azospirillum spp, are endophytic bacteria with beneficial effects on cereals - effects partially attributed to gibberellin production by the microorganisms. Azospirillum lipoferum and Azospirillum brasilense inoculated to rice dy mutant reversed dwarfism in seedlings incubated with [17,17-H-2(2)]GA(20) with formation of [17,17-H-2(2)]GA(1), showing the in vivo capacity to perform the 3 beta -hydroxylation, When Prohexadione-Ca, an inhibitor of late steps in gibberellin biosynthesis, was added to the culture medium, no complementation was observed and no [17,17-H-2(2)]GA(1) was produced. The latter suggests that the bacterial operating enzyme may be a 2-oxoglutarate-dependent dioxygenase, similar to those of plants.