Nitrate alleviates ammonium toxicity in wheat ( Triticum aestivum L.) by regulating tricarboxylic acid cycle and reducing rhizospheric acidification and oxidative damage

作者：Wanying Du, Yunxiu Zhang, Jisheng Si, Yan Zhang, Shoujin Fan, Haiyong Xia, Lingan Kong · 发表于：Plant Signaling & Behavior · 年份：2021 · DOI：10.1080/15592324.2021.1991687 · 被引用次数：38 · 研究领域：Plant nutrient uptake and metabolism、Plant Stress Responses and Tolerance、Plant Micronutrient Interactions and Effects

Ammonium (NH4+) is one of the most important nutrients required by plants. However, a high concentration of NH4+ as the sole nitrogen source suppresses plant growth. Although nitrate (NO3−) can alleviate NH4+ toxicity, the mechanisms underlying this ability have not been fully elucidated. In this study, wheat plants were cultivated in hydroponic solution with 7.5 mM NO3− (control), 7.5 mM NH4+ (sole ammonium, SA) or 7.5 mM NH4+ plus 1.0 mM NO3− (ammonium and nitrate, AN). The results showed that compared with the control, the SA treatment significantly decreased root growth, protein content and the concentrations of most intermediates and the activity of enzymes from the tricarboxylic acid (TCA) cycle. Moreover, increased the activity of plasma membrane H+-ATPase and the rate of H+ efflux along roots, caused solution acidification, and increased the activity of mitochondrial respiratory chain complexes I–IV and the contents of protein-bound carbonyls and malondialdehyde in roots. SA treatment induced ultrastructure disruption and reduced the viability of root cells. Compared with the SA treatment, the AN treatment increased root growth, protein content, the concentrations of most intermediates and the activity of enzymes from the TCA cycle. Furthermore, AN treatment decreased the rate of H+ efflux, retarded medium acidification, decreased protein carbonylation and lipid peroxidation in roots and relieved ultrastructure disruption and increased the viability of root cells. Tak...