杨树不同器官蛋白质和3种氮代谢酶的动态变化

The Dynamic Changes of Contents of Proteins and Three Enzymes of Nitrogen Metabolism in Poplar

以杨树无性系797杨(Populus deltoides×P.euramericana)1年生苗为材料,对不同器官蛋白质含量与硝酸还原酶、谷氨酰胺合成酶、蛋白酶等3种氮代谢关键酶的动态变化与关系进行了研究。结果表明:杨树不同器官(木质部、皮层、根部)蛋白质含量在芽萌发期间(4月中旬)最低,木质部和皮层是杨树越冬期间贮藏蛋白质的主要贮存场所,根部相对较低。叶片和根部硝酸还原酶(NR)活性分别在9月初和10月中旬达到最大,落叶前后明显下降。叶片谷氨酰胺合成酶(GS)活性在5月中旬和10月中旬有两次高峰,与蛋白质变化趋势一致,而根部在芽萌发期间达到最大,与蛋白质变化趋势相反,两部位GS活性落叶前后明显下降。根部蛋白酶在春季芽萌发期间随着贮藏蛋白质的降解其活性逐渐上升,落叶前后,亦呈上升趋势,与蛋白质含量呈显著的负相关关系。

The relationship and the dynamic changes of contents of proteins in different organs and three key enzymes such as nitrate reductase, glutamine synthetase and endopeptidase of nitrogen metabolism were studied based on one-year-old poplar clone 797（Populus deltoides X P. euramericana） seedlings in this paper. The results showed that the contents of proteins in bark, xylem and root decreased obviously during the course of sprouting. The vegetative storage proteins mainly stored in bark and xylem in winter; and the contents in roots were relatively low at that time. The activities of nitrate reductase in leaves and roots reached to maxim in early Sept. and the middle ten days of Oct. respectively, and declined during defoliation. The activities of glutamine synthetase in leaves had two-peak curves, one was in the middle ten days of May,another was in Oct., the change tendency was consistent with the contents of proteins; and it reached to maxim in roots during sprouting, contrary to the change tendency of proteins and they also declined during defoliation in both places. The activities of endopeptidase in roots rised gradually with the degradation of vegetative storage proteins during sprouting, and also kept rising during defoliation. There was distinct negative linear relativity between the contents of total proteins and endopeptidase activities in roots.