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作 者 ：周忠新;袁永泽;王云华;欧吉权;张楚富

期 刊 ：武汉植物学研究 2005年 23卷 6期 页码：572-576

关键词：谷氨酰胺合成酶；磷酸烯醇式丙酮酸羧化酶；异柠檬酸脱氢酶；碳-氮平衡；水稻；

Keywords:Glutamine synthetase, Phosphoenolpyruvate carboxylase, Isocitrate dehydrogenase, Carbon-nitrogen balance, Rice,

摘 要 ：糖、有机酸以及氨基酸影响碳-氮代谢过程中的相关酶的基因表达和活性。将蔗糖分别加入到含有相同氮素浓度的(NH₄)₂SO₄(NH₄⁺)或丙氨酸(Ala)作为氮源的营养液中培养水稻,测定幼苗根的谷氨酰胺合成酶(GS)、依赖于NADH的谷氨酸合酶(NADH-GOGAT)、磷酸烯醇式丙酮酸羧化酶(PEPC)和依赖于NADP的异柠檬酸脱氢酶(NADP-ICDH)的活性。结果显示,蔗糖诱导NH₄⁺氮源中幼苗根的GS、NADH-GOGAT活性,抑制Ala氮源中幼苗根的这两种酶活性,蔗糖对PEPC和NADP-ICDH活性的影响也不同;未加蔗糖时,以Ala作为氮源的幼苗根的GS、NADH-GOGAT、PEPC和NADP-ICDH的活性明显高于以NH₄⁺为氮源时的活性;生物量和蛋白质水平的变化与上述参数的变化基本一致。基于Ala碳骨架的存在,这些结果表明,碳/氮平衡是影响这些酶活性差别表达的主要原因。

Abstract:Sugar,organic acid and amino acids play important effects on gene expression and enzyme activities involved in carbon and nitrogen metabolism.With rice cultivating,sucrose was superinduced to the nutrient solution containing(NH₄)₂SO₄(NH₄⁺) or L-Ala,which contained same nitrogen content,and then determined the activities of glutamine synthetase (GS),NADH-dependent glutamate synthase(NADH-GOGAT),phosphoenolpyruvate carboxylase(PEPC),NADP-dependent isocitrate dehydrogenase(NADP-ICDH).The results showed that sucrose induced markedly the enzyme activities of GS and NADH-GOGAT in roots of seedlings with NH₄⁺ as the nitrogen source,however,inhibited them in roots of seedlings growing in L-Ala nitrogen source.Sucrose had different effects on the activity changes of PEPC and NADH-ICDH.Without sucrose supplementation,the activities of GS,NADH-GOGAT,PEPC,NADP-ICDH in the roots of rice seedlings growing in L-Ala nitrogen source were higher than that with NH₄⁺ as the nitrogen source.The changes trend in biomass and protein content were coincident with the former parameters.Based on the additional carbon skeleton of Ala compared to(NH₄)₂SO₄,these resulted suggested that carbon/nitrogen balance play an important role in the different regulation of the enzyme activity.

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