Aeration stimulates the rice growth and nitrogen (N) metabolism; in which, the glutamate accumulation limited by the glutamate dehydrogenase pathway after ammonia uptake may control root N metabolism during aeration. Increasing rhizosphere oxygen content greatly improves rice growth and biomass. To study the intrinsic mechanism involved in nitrogen (N) metabolism, a hydroponic experiment was conducted by supplying two different oxygen levels to two different rice genotypes. Compared to the hypoxia-resistant cultivar (Nip; japonica rice 'Nipponbare'), the hypoxia-sensitive cultivar (U502; upland rice 'Upland 502') presented with severe oxidative damage under the lack of aeration. However, aeration significantly reduced root oxidative damage by enhancing root antioxidant capacity and leaf photosynthesis especially in U502, and significantly increased nitrate (NO3-) and ammonia (NH4+) uptake and upregulated the expression of the genes controlling these processes. Additional NO3- was mainly incorporated into amino acids in the leaves whereas NH4+ assimilation occurred mostly in the roots. The 15N gas chromatography-mass spectrometry analysis demonstrated that aeration had no influence on the compositions of the individual amino acids derived from 15NO3- in the roots, but increased labeled glutamic acid (Glu), asparagine, γ-aminobutyric acid, and alanine in 15NH4+-treated roots. Aeration inhibited root glutamate synthetase activity but this did not inhibit 15N-Glu production from 15NH4+. In contrast, aeration upregulated isocitrate dehydrogenase and glutamate dehydrogenase. These mechanisms and soluble carbohydrates may constitute an alternative pathway for Glu production in which amino acid metabolism is enhanced after NH4+ uptake during aeration. Therefore, the rice growth-enhancing effect of aeration is closely correlated with root redox equilibrium, N uptake, and amino acid metabolism. Glutamic acid accumulation is limited by the glutamate dehydrogenase pathway after NH4+ uptake and may control root N metabolism during aeration.

中文翻译：

---

氨吸收后谷氨酸脱氢酶介导的氨基酸代谢促进了通气条件下水稻的生长。

曝气促进水稻生长和氮（N）代谢；其中，氨吸收后受谷氨酸脱氢酶途径限制的谷氨酸积累可能控制通气过程中的根氮代谢。增加根际氧含量大大提高了水稻的生长和生物量。为了研究氮 (N) 代谢的内在机制，通过向两种不同的水稻基因型提供两种不同的氧气水平进行了水培实验。与耐缺氧品种（Nip；粳稻'Nipponbare'）相比，缺氧敏感品种（U502；旱稻'Upland 502'）在缺氧条件下会出现严重的氧化损伤。然而，通气通过增强根系抗氧化能力和叶片光合作用显着减少根系氧化损伤，尤其是在 U502 中，并显着增加硝酸盐 (NO3-) 和氨 (NH4+) 的吸收，并上调控制这些过程的基因的表达。额外的 NO3- 主要结合到叶片中的氨基酸中，而 NH4+ 同化主要发生在根部。15N气相色谱-质谱分析表明，曝气对根中15NO3-衍生的单个氨基酸的组成没有影响，但增加了15NH4+中的标记谷氨酸（Glu）、天冬酰胺、γ-氨基丁酸和丙氨酸。 -处理过的根。曝气抑制了根谷氨酸合成酶的活性，但这并没有抑制 15NH4+ 产生 15N-Glu。相反，通气上调异柠檬酸脱氢酶和谷氨酸脱氢酶。这些机制和可溶性碳水化合物可能构成 Glu 产生的替代途径，其中在通气期间吸收 NH4+ 后氨基酸代谢得到增强。因此，曝气对水稻生长的促进作用与根系氧化还原平衡、氮吸收和氨基酸代谢密切相关。谷氨酸的积累受到 NH4+ 吸收后谷氨酸脱氢酶途径的限制，并且可能在通气过程中控制根系 N 代谢。