ABSCISIC-ACID ENZYME-LINKED IMMUNOSORBENT ASSAYS IN RICE GRAINS

The monoclonal antibody from Idetek which was raised against (+/-)ABA(C-4') BSA are commercially available. It is reported to recognize only free (+/-) ABA. Using ELISA based on competitive binding free and enzyme-linked ABA, they give estimates of free ABA in crude extracts of rice grains. The best estimates of free ABA were obtained from adequate dilute of extract solutions. Free ABA was determined by ELISA during milky stage and yellow-ripe stage in rice grains. The results showed that free ABA in grains distributed much in caryopsis than the hulls. They were 1.61 pg and 0.068 pg per grain, respectively. Free ABA per grain decreased from 1.678 pg to 0.127 pg during the investigated period. The concentration of free ABA at milky stage was higher, 100.42 ng/g.f.w, and then dropped significantly to 5.31 ng/g.f.w, at yellow-ripe stage. Dramatic change of free ABA levels in developing rice kernel might play a significant role to regulate seed metabolic status.