NaCl对水稻谷氨酸合酶和谷氨酸脱氢酶的胁迫作用

EFFECT OF NaCl STRESS ON GLUTAMATE SYNTHASE AND GLUTAMATE DEHYDROGENASE OF RICE PLANTS

在 Na Cl的胁迫下 ,水稻幼苗根和叶的谷氨酸合酶和谷氨酸脱氢酶的活性随着营养液中的 Na Cl浓度的升高而降低 ;游离 NH+ 4 在叶中积累 ,在根中未见明显变化。与根相比 ,叶对 Na Cl的胁迫作用更为敏感。叶的 NADH- GOGAT和 NADH- GDH活性在 Na Cl胁迫下降低的程度明显大于根。无论是否有 Na Cl存在 ,根的 NADH- GDH活性明显高于叶。 GS/GDH比值分析提示 ,在对照下 ,根中的 NH+ 4 的同化以 GS- GOGAT途径为主 ;而在 Na Cl胁迫下 ,GS- GOGAT途径明显削弱 ,GDH途径在 NH+ 4 的同化中的作用明显加强。无论是否有 Na Cl的存在 ,叶的 NH+ 4 同化途径都是以 GS- GOGAT为主。

Glutamate synthase(GOGAT) and glutamate dehydrogenase(GDH) activity in the roots and leaves of rice seedlings were decreased under NaCl stress.NH + 4 level in leaves was increased significantly due to NaCl stress,but the content of NH + 4 in roots was not altered obviously,irrespective of NaCl treatment.As compared with root, leaf was more sensitive to NaCl stress.The reduction of the activity of NADH GOGAT and NADH GDH in leaves was more than that in roots.Whether NaCl was added or not to the nutrient solution,NADH GDH activity of roots was much higher than that of leaves.Analysis for GS GDH ratio showed that GS GOGAT cycle was main pathway of ammonium assimilation in the control plant roots,but under NaCl stress,GDH pathway was strengthened obviously.Irrespective of NaCl treatment,GS/GOGAT cycle was main pathway in leaves.