Endogenous gibberellins from callus cultures of maize

Abstract

This paper reports the identification of gibberellin A 1(GA 1), GA 17, GA 19, GA 20, GA 29, and GA 53 from extracts of normal (wild-type) maize callus using full-scan GC-Mass Spectrometry and Kovats retention indices (KRIs). In addition, evidence is presented for the presence of GA 8 based on its molecular ion at the appropriate KRI. In a preliminary experiment, the presence of GA 3, GA 5, and GA 44 was suggested, based on GC-selected ion monitoring (SIM); however, the presence of these GAs was not confirmed by full-scan GC-Mass Spectrometry. The information represents the first identification of GAs from maize callus. All of the identified GAs are members of the early-13-hydroxylation pathway, a biosynthetic pathway that leads to bioactive GA 1. GA 1, GA 8, GA 19, GA 20, and GA 29 were quantified from GC-SIM isotopic dilution data. GA 17 and GA 53 were quantified from GC-SIM data by comparing the ion intensity from each gibberellin to a known amount of a GA 19 standard. The levels of the identified GAs ranged from 6 pg g −1 fr. wt to 210 pg g −1 fr. wt.