Low-Nitrogen Stress Stimulates Lateral Root Initiation and Nitrogen Assimilation in Wheat: Roles of Phytohormone Signaling

文献类型： 外文期刊

第一作者： Lv Xuemei

作者： Lv Xuemei;Zhang Yunxiu;Zhang Yan;Zhang Bin;Xia Haiyong;Du Wanying;Kong Lingan;Lv Xuemei;Zhang Yan;Du Wanying;Fan Shoujin;Kong Lingan;Hu Ling

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关键词： Ammonium; Low-N stress; Nitrate; Root; Wheat

期刊名称：JOURNAL OF PLANT GROWTH REGULATION （ 影响因子：4.169； 五年影响因子：4.038 ）

ISSN： 0721-7595

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收录情况： SCI

摘要： Nitrogen (N) deficiency is one of the factors limiting crop productivity worldwide. As major forms of N, nitrate (NO3-) and ammonium (NH4+) regulate plant growth as signals. Although there are abundant studies on the response of many plants to N stress, the mechanism by which wheat (Triticum aestivum L.) roots adapt to low N, especially to low-NH4+ stress, has not been fully elucidated. In this study, wheat seedlings were planted in 1/2-strength Hoagland's solution containing 5 mM NO3-, 0.1 mM NO3-, or 0.1 mM NH4+ to characterize root physiological responses to N deficit. Under low-N stress, root fresh weight, lateral root number increased compared with those under control conditions. Moreover, the concentrations of indole-3-acetic acid (IAA), cytokinins (CKs), gibberellin (GA(3)), and jasmonic acid (JA) increased, while the salicylic acid (SA) concentration decreased under low-N stress. Assays using enzyme-linked immunosorbent assay (ELISA) and non-invasive micro-test technology (NMT) showed that H+-ATPase activity, the H+ efflux, and the IAA influx increased, while N influx decreased under low-N stress. Further study revealed that low-NO3- stress increased nitrate reductase and glutamine synthetase activities, while low-NH4+ stress increased the activities of glutamine synthetase and glutamate synthase. In conclusion, low-N stress altered root IAA, CKs, GA(3), JA, and SA concentrations; increased H+-ATPase activity and H+ efflux; promoted an increase in lateral root number and thus N absorption area. Besides, low-N stress increased the activities of key enzymes related to N assimilation, promoted protein biosynthesis, and ultimately enhanced root growth.

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