不同季节桉树叶可溶性蛋白质及两种酶的动态特征

Abstract

探讨桉树可溶性蛋白质及与氮代谢相关的两种酶的季节性变化，为提高氮素利用率，指导合理施肥及提高产量提供理论基础。在观察物候期基础上采用紫外分光度法对不同季节的桉树氮素营养进行了初步研究，测定不同季节桉树叶中与氮素代谢相关的可溶性蛋白质含量、谷氨酰胺合成酶及氨酸合成酶活性的变化。试验结果表明：1) 桉树叶片中可溶性蛋白质含量表现为明显的季节性规律，与气象因子及桉树的生理代谢密切相关。随着桉叶的成长，可溶性蛋白质含量增加，到了秋季叶内氮化物发生转移和再分配，可溶性蛋白质含量减少。2) 桉叶中谷氨酰胺合成酶活性主要与氮素的转移和再分配有关，其活性随含氮物质的转移和分配而改变。3) 谷氨酸合成酶活性与氮素的转移和再分配有关，在GS-GOGAT途径中与谷氨酰胺合成酶起协同作用。综合分析得出，桉树在春季处于快速生长期，氮素需求量较大，桉树叶内含氮化合物不断增多，谷氨酰胺合成酶及谷氨酸合成酶活性增加；秋季桉叶内贮藏氮素在有关酶的调控下发生转移和再分配，贮藏氮素减少。 To investigate the seasonal variation of Eucalyptus soluble protein and two enzymes related to ni-trogen metabolism, it would provide theoretical basis for improving the utilization rate of nitrogen and increasing the yield. The experiment made a preliminary research on nitrogen’s nutrition of Eucalyptus in different seasons, determinated the change of soluble protein content, glutamine synthetase and glutamate synthase activity of Eucalyptus leaves in different seasons that related to nitrogen metabolism. The results showed that: 1) The soluble protein content of Eucalyptus leaves showed seasonal pattern obviously, which was closely related to meteorological factors and phys-iological metabolism of Eucalyptus. With the growth of Eucalyptus leaves, it would increase the content of soluble protein. In the autumn nitrogenous compounds of leaves could transfer and re-distribute the content of soluble protein. 2) The activity of glutamine synthetase of Eucalyptus leaves was mainly related to the transfer and redistribution of the nitrogenous compounds. 3) The activity of glutamate synthase was related to the transferred and distributed of nitrogenous com-pounds, which played a synergistic role with glutamine synthetasein in the GS-GOGAT pathway. It was concluded that the Eucalyptus was in the rapid growth period in spring for a greater demand for nitrogen. The increased of nitrogenous compounds of Eucalyptus leaves, increased the activity of glutamine synthetase and glutamate synthase. The nitrogenous compounds in the leaves of Eu-calyptus were transferred and redistributed under the regulation of the enzyme in autumn, the storage of nitrogen decreased.