Changes in Activity of Glutamine Synthetase and NADH-glutamate Synthase During Germination of Rice Seeds
WANG Qi-Hai LIN Qing-Hua ZHANG Chu-Fu WEI Guo-Wei YUAN Yong-Ze (Key Laboratory of MOE for Plant Developmental Biology, Wuhan University, Wuhan 430072)
The changes in activity of glutamine synthetase and NADH-glutamate synthase in endosperms, coleoptiles, and roots were determined during the germination of rice (Oryza sativa L. cv Tai Chong Native 1) seeds. GS activity in the endosperms and coleoptiles increased during the germination(Fig.1). The increase in GS activity of the coleoptile was more remarkable than that of the endosperm. GS activity in roots was higher than that of endosperms, but the activity decreased gradually with germinating course (Fig.1). The tendency of the change in activity of NADH-GOGAT activity change was similar to that of GS in these tissues (Fig.5). Only GSe (endosperm GS) and GSra activity bands were detected by the activity staining in the endosperms and roots, respectively(Fig.2A and C). Besides GS1 activity, GS2 activity was also observed in the coleoptiles during the later phase of germination(Fig.2B). The result of Western blotting showed that GSe of the endosperms is a cytosolic enzyme as GS1 and GSra (Fig.4). The changes in GS and NADH-GOGAT activities in these tissues suggest that the cytosolic GS-NADH-GOGAT cycle may be the main pathway for ammonium assimilation.