Impact of the C-N status on the amino acid profile in tobacco source leaves
Impact of the C-N status on the amino acid profile in tobacco source leaves
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DOI：
10.1111/j.1365-3040.2006.01580.x
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发表时间：
2006-11-01
影响因子：
7.3
通讯作者：
Stitt, Mark
中科院分区：
文献类型：
--
作者：
Fritz, Christina;Mueller, Cathrin;Stitt, Mark
研究了碳氮营养状况对烟源叶片氨基酸组成的影响。使用的处理包括在不同的光强度下生长植物，使用反义RBCS（小亚基的核酮糖-1，5-二磷酸羧化酶/加氧酶）构建体来抑制Rubisco活性，在12或0.5 mM硝酸盐上生长植物，将野生型与具有硝酸还原酶（NIA）活性的小和大的降低的基因型进行比较，以及在昼夜循环期间的不同时间对植物进行取样。这种实验的组合提供了关于氨基酸水平如何响应几种输入的信息，包括C和N状态，硝酸盐，过量的光和明暗转换。使用主成分分析、回归分析和通过归一化总氨基酸库上的每种单独氨基酸的水平来分析数据集。大多数氨基酸在C或N状态降低时呈下降趋势，在昼夜循环中白天上升，晚上下降。然而，个别氨基酸往往表现出偏离的反应。此外，没有证据表明反馈抑制次要氨基酸的合成，无论是内部或之间的途径，当18个单独的氨基酸提供给离体叶片。结果表明，氨基酸代谢的调节，例如通过C和N状态，导致许多氨基酸的定性相似的反应，但涉及单个氨基酸生物合成途径内或之间的反馈抑制的稳态机制并不严格。所有上述输入影响苯丙氨酸的水平，苯丙氨酸是一种氨基酸，也是次级代谢的重要部分的底物。谷氨酸的水平非常稳定，表明未知的机制稳定了这种关键的中心氨基酸的浓度。代谢物水平分析和饲养实验表明，2-酮戊二酸在调节谷氨酸水平中起着重要作用。谷氨酸是最有效的NIA活性的抑制剂时，18个单独的氨基酸供应离体叶片。饲喂谷氨酸和其他下游氨基酸，导致谷氨酰胺的增加，表明谷氨酸对铵代谢发挥反馈调节作用。
This paper investigates the influence of the carbon (C) and nitrogen (N) status on the amino acid profile in tobacco source leaves. Treatments used included growing plants at different light intensities, using an antisense RBCS (small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase) construct to inhibit Rubisco activity, growing plants on 12 or 0.5 mM nitrate, comparing wild-types with genotypes that have small and large decreases in nitrate reductase (NIA) activity, and sampling plants at different times during the diurnal cycle. This combination of experiments provides information on how amino acid levels respond to several inputs including the C and N status, nitrate, excess light and light-dark transitions. The data set was analysed using principal component analysis, regression analysis and by normalizing the level of each individual amino acid on the total amino acid pool. Most amino acids show a downward trend when the C or the N status is decreased, and rise during day and fall at night during the diurnal cycle. However, individual amino acids often showed deviating responses. Furthermore, no evidence was found for feedback inhibition of minor amino acid synthesis, either within or between pathways, when 18 individual amino acids were supplied to detached leaves. Results indicate that regulation of amino acid metabolism, for example by the C and N status, leads to qualitatively similar responses of many amino acids, but homeostatic mechanisms involving feedback inhibition within or between individual amino acid biosynthesis pathways are not stringent. All of the above inputs affect the level of phenylalanine, an amino acid that is also the substrate for an important sector of secondary metabolism. The levels of glutamate were remarkably constant, indicating that unknown mechanisms stabilize the concentration of this key central amino acid. Analyses of metabolite levels and feeding experiments indicated that 2-oxoglutarate plays an important role in regulating glutamate levels. Glutamate was the most effective inhibitor of NIA activity when 18 individual amino acids were supplied to detached leaves. Feeding glutamate, and other downstream amino acids, led to an increase of glutamine, indicating glutamate exerts feedback regulation on ammonium metabolism.