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首页> 外文会议>International Plant Nutrition Colloquium; 2005; Beijing >Preferential provision of carbon skeletons for amide synthesis during ammonium nutrition in the roots of various plants
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Preferential provision of carbon skeletons for amide synthesis during ammonium nutrition in the roots of various plants

机译：在铵态氮营养期间，在各种植物的根部优先提供碳骨架以进行酰胺合成

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Carbon skeletons are required for the synthesis of amides in roots during ammonium assimilation. The synthesis of amides from glucose-~(14)c and changes in the levels of major amino acids were investigated in the roots of several plant species, which were supplied with or without ammonium-N in the nutrient solution. Ammonium nutrition significantly increased the incorporation of ~(14)C from glucose-~(14)C into the soluble amino acid fraction and decreased incorporation into the organic acid fraction in rice, cucumber and soybean roots. In rice and soybean roots, asparagine accounted for the highest proportion (40%) of labelled soluble amino acids but glutamine occupied less than 10%. In cucumber, glutamine was labelled three times more than asparagine. The ratio of C5 (glutamate + glutamine) to C4 amino acids (aspartate + asparagine) was six times higher in cucumber than in rice and soybean. The re-supply of arrrmonium-N to plants grown in N-free media greatly increased the levels of total free amino acids in the roots of all examined plants. In rice, corn, Panicum miliaceum, Eleusine coracana and soybean, the level of asparagine was higher than that of glutamine. Two dicots, cucumber and Amaranthus mongostanus, exhibited glutamine to asparagine ratios of 20:1 and 16:1, respectively. The total content of C4 amino acids was larger in rice, P. miliaceum, E. coracana and soybean and slightly larger in com than that of C5 amino acids whereas the reverse was true in dicots, cucumber and A. mongostanus. These results suggest that the C4, carbon skeleton is needed for the active synthesis of asparagine in gramineous species and soybean (a leguminous dicot) whereas the continuous supply of the C5 carbon skeleton is required for predominant glutamine synthesis in non-leguminous dicots like cucumber, tomato and A. mongostanus on exposure to ammonium-N.
机译：铵同化过程中，碳骨架是根中酰胺合成所必需的。在几种植物的根中研究了由葡萄糖-（14）c合成酰胺和主要氨基酸水平的变化，这些植物在营养液中添加或不添加铵态氮。铵营养显着提高了水稻，黄瓜和大豆根中〜（14）C从葡萄糖-〜（14）C到可溶性氨基酸组分的掺入，并减少了到有机酸组分的掺入。在水稻和大豆根中，天冬酰胺占标记可溶性氨基酸的最高比例（40％），但谷氨酰胺占不到10％。在黄瓜中，谷氨酰胺的标记量是天冬酰胺的三倍。黄瓜中C5（谷氨酸+谷氨酰胺）与C4氨基酸（天冬氨酸+天冬酰胺）的比率是水稻和大豆的六倍。向在无氮培养基中生长的植物重新补充Ar-N大大增加了所有受检植物根中总游离氨基酸的水平。在稻米，玉米，Pan药，椰油松和大豆中，天冬酰胺的含量高于谷氨酰胺。两个双子叶植物，黄瓜和and菜，分别表现出谷氨酰胺与天冬酰胺的比率为20：1和16：1。水稻，纤毛假单胞菌，大肠杆菌和大豆中C4氨基酸的总含量比C5氨基酸的总含量高，而com的总含量则略高于C5氨基酸，而双子叶植物，黄瓜和蒙古曲霉则相反。这些结果表明，在禾本科物种和大豆（豆科植物双子叶植物）中有效合成天冬酰胺需要C4碳骨架，而在非豆科植物双子叶植物（如黄瓜）中，谷氨酰胺的合成需要持续供应C5碳骨架。番茄和蒙古芒草暴露于铵态氮中。

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