Abstract:The production and characterization of a monoclonal antibody (MAb AB10) against GA3-glucoside as well as GA3 is described. MAb AB10 was derived from an immunogen in which human serum albumin (HSA) was linked to GA3 at carbon-3. This antibody showed high affinity for GA3-glucoside as well as for 13-hydroxy gibberellins (GA1, GA3, GAs, etc). The affinity of MAb AB10 for 13-hydroxy GAs was significantly reduced by methylation of the 7-oic acid but not by glycosylation of 3-hydroxyl group. Based on this antibody, both of competitive enzyme-linked immunosorbent assays (ELISAs) for GA3-glucoside and for GA3 were developed. These two ELISAs displayed linear detection ranges from 0.2 pmol to 20 pmol. Using these assays, the fluctuation of GA3-1ike and GA3-glucoside-like sub-stances in the leaves of Rurnex japonicus was investigated. The results indicated that the glycosylation of free GAs was connected with leaf senescence and that the function of 6-ben- zyl amino purine in retarding the leaf senescence was probably related to delaying the process of glycosylation of free GAs.