Exogenous calcium affects nitrogen metabolism in root-zone hypoxia-stressed muskmelon roots and enhances short-term hypoxia tolerance
Exogenous calcium affects nitrogen metabolism in root-zone hypoxia-stressed muskmelon roots and enhances short-term hypoxia tolerance
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外源钙影响根区缺氧胁迫的甜瓜根氮代谢并增强短期缺氧耐受性
DOI：
10.1016/j.jplph.2011.01.022
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发表时间：
2011-07-15
影响因子：
4.3
通讯作者：
Juan, Li
中科院分区：
文献类型：
--
作者：
Gao, Hongbo;Jia, Yongxia;Juan, Li
研究了短期根区缺氧胁迫和外源施钙或缺氧营养液缺乏对甜瓜品种西育1号根系氮代谢的影响。幼苗在低氧营养液中生长6d，植株生长和可溶性蛋白浓度显著降低。硝态氮(3)（-）摄取率及硝态氮还原酶和谷氨酸合成酶活性显著升高。我们还发现，根中硝酸盐、铵、氨基酸、热稳定蛋白、多胺、H(2)O(2)含量较高，多胺氧化酶活性也较高。与低氧胁迫下的反应相比，外源钙处理导致植株重量、光合参数、NO(3)（-）吸收率和硝酸盐、铵、氨基酸（如谷氨酸、脯氨酸、甘氨酸、胱氨酸、γ -氨基丁酸）、可溶性和热稳定蛋白、游离精胺和不溶性结合多胺的含量显著增加。同时，外源钙处理显著提高了硝酸盐还原酶、谷氨酰胺合成酶和谷氨酸合成酶的活性，降低了二胺和多胺氧化酶的活性，降低了缺氧条件下根系H(2)O(2)含量。然而，营养液中缺钙降低了植株重量、光合参数、NO(3)（-）还原、氨基酸（如丙氨酸、天冬氨酸、谷氨酸、γ -氨基丁酸）、蛋白质、除游离腐胺外的所有多胺，以及谷氨酸合成酶和谷氨酰胺合成酶的活性。低氧- ca处理显著提高了水稻对NO(3)（-）的吸收速率、多胺氧化酶活性和H(2)O(2)含量。同时，在常氧条件下，外源钙对硝酸盐的吸收转化、光合参数和植物生长影响不大。这些结果表明，钙赋予甜瓜短期耐缺氧能力，很可能是通过促进硝酸盐的吸收，加速其向氨基酸、热稳定蛋白或多胺的转化，以及减少多胺在甜瓜幼苗中的降解。(C) 2011爱思唯尔有限公司版权所有。
We investigated the effects of short-term root-zone hypoxic stress and exogenous calcium application or deficiency in an anoxic nutrient solution on nitrogen metabolism in the roots of the muskmelon cultivar Xiyu No. 1. Seedlings grown in the nutrient solution under hypoxic stress for 6d displayed significantly reduced plant growth and soluble protein concentrations. However, NO(3)(-) uptake rate and activities of nitrate reductase and glutamate synthase were significantly increased. We also found higher amounts of nitrate, ammonium, amino acids, heat-stable proteins, polyamines, H(2)O(2), as well as higher polyamine oxidase activity in the roots. In comparison to the reactions seen under hypoxic stress, exogenous calcium application led to a marked increase in plant weights, photosynthesis parameters, NO(3)(-) uptake rate and contents of nitrate, ammonium, amino acids (e.g., glutamic acid, proline, glycine, cystine, gamma-aminobutyric acid), soluble and heat-stable proteins, free spermine, and insoluble bound polyamines. Meanwhile, exogenous calcium application resulted in significantly increased activities for nitrate reductase, glutamine synthetase, and glutamate synthase but decreased activities for diamine and polyamine oxidase, as well as lower H(2)O(2) content in roots during exposure to hypoxia. However, calcium deficiency in the nutrient solution decreased plant weight, photosynthesis parameters, NO(3)(-) reduction, amino acids (e.g., alanine, aspartic acid, glutamic acid, gamma-aminobutyric acid), protein, all polyamines except for free putrescine, and the activities of glutamate synthase and glutamine synthetase. Additionally, there was an increase in the NO(3)(-) uptake rate, polyamine oxidase activity and H(2)O(2) contents under hypoxia-Ca. Simultaneously, exogenous calcium had little effect on nitrate absorption and transformation, photosynthetic parameters, and plant growth under normoxic conditions. These results suggest that calcium confers short-term hypoxia tolerance in muskmelon, most likely by promoting nitrate uptake and accelerating its transformation into amino acids, heat-stable proteins or polyamines, as well as by decreasing polyamine degradation in muskmelon seedlings. (C) 2011 Elsevier GmbH. All rights reserved.