Abstract
The endogenous gibberellins (GAs) of rice were analyzed during seed germination and during the regeneration of plantlets from embryogenic cells. Four 13-hydroxylated (13-OH) GAs (GA53, GA19, GA20, and GA1) were identified by combined gas chromatography-selected ion monitoring (GC-SIM) from the seeds at every stage of germination examined. A significant increase in their level was observed at the time shoot elongation started. No GA was detected in the embryogenic cells before transferring into a regeneration medium, while the occurrence of 13-OH GAs was confirmed by full-scan GC-MS or GC-SIM during the regeneration of plantlets. These results indicate that the early-13-hydroxylation pathway of GA biosynthesis operated during embryo development and seed germination.
