Nitrogen is one of the main factors that affect plant growth and development. However, high nitrogen concentrations can inhibit both shoot and root growth, even though the processes involved in this inhibition are still unknown. The aim of this work was to identify the metabolic alterations that induce the inhibition of root growth caused by high nitrate supply, when the whole plant growth is also reduced. High nitrate altered nitrogen and carbon metabolism, reducing the content of sugars and inducing the accumulation of Ca2+ and amino acids, such as glutamate, alanine and γ-aminobutyrate (GABA), that could act to replenish the succinate pool in the tricarboxylic acid cycle and maintain its activity. Other metabolic alterations found were the accumulation of the polyamines spermidine and spermine, and the reduction of jasmonic acid (JA) and the ethylene precursor aminocyclopropane-1-carboxylic acid (ACC). These results indicate that the growth root inhibition by high NO3- is a complex metabolic response that involves GABA as a key link between C and N metabolism which, together with plant growth regulators such as auxins, cytokinins, abscisic acid, JA, and the ethylene precursor ACC, is able to regulate the metabolic response of root grown under high nitrate concentrations.

中文翻译：

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1-氨基环丙烷-1-羧酸、γ-氨基丁酸和D-葡萄糖在调节高硝酸盐诱导的玉米根生长抑制中的相互作用

氮是影响植物生长发育的主要因素之一。然而，高氮浓度可以抑制芽和根的生长，尽管这种抑制所涉及的过程仍然未知。这项工作的目的是确定当整个植物生长也减少时，由高硝酸盐供应引起的抑制根生长的代谢改变。高硝酸盐改变了氮和碳的代谢，降低了糖的含量并诱导了 Ca2+ 和氨基酸的积累，例如谷氨酸、丙氨酸和 γ-氨基丁酸 (GABA)，它们可以在三羧酸循环中补充琥珀酸池和保持其活性。发现的其他代谢改变是多胺亚精胺和精胺的积累，以及茉莉酸 (JA) 和乙烯前体氨基环丙烷-1-羧酸 (ACC) 的还原。这些结果表明，高 NO3- 对根生长的抑制是一种复杂的代谢反应，涉及 GABA 作为 C 和 N 代谢之间的关键环节，以及植物生长调节剂，如植物生长素、细胞分裂素、脱落酸、JA 和乙烯前体 ACC 能够调节在高硝酸盐浓度下生长的根的代谢反应。