Evidence for the direct 2beta- and 3beta-hydroxylation of [2H2]GA20-13-O-[6'-2H2]glucoside in seedlings of Phaseolus coccineus.

[17-(2) H-2 ]GA(20) -13-O-[6'-(2) H-2 ]glucoside was synthesized and applied to seedlings of Phaseolus coccineus L. After incubation for 72 h the conjugate metabolites were purified and shown by LC-ESI-tandem-MS and GC-MS to be [17-(2) H-2 ]GA(1) -13-O-[6'-(2) H-2 ]glucoside and [17-(2) H-2 ]GA(29) -13-O-[6'-(2) H-2 ]glucoside. This is the first evidence for the conversion of intact GA-O-glucosides, and represents an additional metabolic pathway of the gibberellin metabolism in P. coccineus L. The results indicate that intact GA-O-glucosides are accepted by 2- and 3-oxidases in the plant.