不同浓度的NO_3^-和 NH_4^+对小麦根谷氨酰胺合成酶及其相关酶的影响

INFLUENCE OF DIFFERENT CONCENTRATIONS OF NO_3^- AND NH_4^+ ON THE ACTIVITY OF GLUTAMINE SYNTHETASE AND OTHER RELEVANT ENZYMES OF NITROGEN METABOLISM IN WHEAT ROOTS

利用酶活性测定和 Northern分子杂交等技术 ,研究了小麦幼苗根在不同浓度的 Na NO3 和(NH4) 2 SO4的供应下 ,其谷氨酰胺合成酶 (GS)、天冬酰胺合成酶 (AS)、谷氨酸脱氢酶 (GDH)、硝酸还原酶 (NR)以及 GS- m RNA的变化。结果表明 :NH+ 4 处理的小麦 ,其根部 GS活性比 NO-3 处理的高 ;高浓度处理的比低浓度处理的高 ;Northern杂交结果说明 GS- m RNA转录量与 GS活性一致 ;3mmol/ L NO-3促进了 AS的活性。AS酶活性变化与 GS酶活性变化无明显依赖关系。在实验的条件下 ,没能测出 GDH的活性 ,不同浓度的 NO-3 和 NH+ 4 处理对 NR活性没有明显的规律。

Influence of different concentrations of NO - 3 and NH + 4 on the activity of glutamine synthetase (GS),asparagine synthetase (AS), glutamate dehydrogenase (GDH),nitrate reductase (NR) and the changes of GS mRNA in wheat roots have been studied with enzymes activity assay and Northern blot.The results showed that the higher GS activity was found in roots of wheat when NH + 4 N was the sole nitrogen source than when NO - 3 N was the sole nitrogen source. GS mRNA of Northern blot was simillar to GS activity. 3 mmol/L NO - 3 promoted the activity of AS. The change of AS was independent of the change of GS. GDH activity was not been detected, and change in regulation of NR activity was not found.