Water shortage limits plant growth and development by inducing physiological and metabolic disorders, while arbuscular mycorrhizal (AM) symbiosis can improve plant adaptation to drought stress by altering some metabolic and signaling pathways. In this study, root growth and levels of some metabolites (polyamines, amino acids, and malic acid [MA]) and key enzymes were examined in AM-inoculated and non-inoculated (NM) maize seedlings under different water conditions. The results showed that AM symbiosis stimulated root growth and the accumulation of putrescine (Put) during initial plant growth. Root Put concentration significantly decreased in AM compared with NM plants under water stress; correspondingly, Put degradation via diamine oxidase into γ-aminobutyric acid (GABA) occurred. Moreover, glutamine concentration and the activity of N assimilation enzymes (nitrate reductase and glutamine synthetase) were higher in roots of AM than NM plants under moderate water stress. The activity of GABA transaminase and malic enzyme, and MA concentration were also higher in roots of AM than NM plants under moderate water stress. Our results indicated that Put catabolism along with improved N assimilation and the accumulation of GABA and MA were the key metabolic processes in roots of AM maize plants in response to water stress.

中文翻译：

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丛枝菌根诱导了水胁迫玉米植株根中的腐胺降解为γ-氨基丁酸，苹果酸积累并改善了氮的吸收。

缺水会通过诱导生理和代谢紊乱来限制植物的生长和发育，而丛枝菌根（AM）共生可以通过改变某些代谢和信号传导途径来提高植物对干旱胁迫的适应性。在这项研究中，在不同水分条件下，在AM接种和非接种（NM）玉米幼苗中检测了根的生长以及某些代谢产物（多胺，氨基酸和苹果酸[MA]）和关键酶的水平。结果表明，AM共生刺激了植物初始生长过程中根系的生长和腐胺的积累。与水分胁迫下的NM植物相比，AM中的根系浓度显着降低。相应地，通过二胺氧化酶将其降解为γ-氨基丁酸（GABA）。此外，在中等水分胁迫下，AM根部的谷氨酰胺浓度和N同化酶（硝酸还原酶和谷氨酰胺合成酶）的活性高于NM植​​物。在适度水分胁迫下，AM根系中GABA转氨酶和苹果酸的活性和MA浓度也高于NM植​​物。我们的结果表明，Put分解代谢与改善的N同化以及GABA和MA的积累是AM玉米植物根系响应水分胁迫的关键代谢过程。