Fujian Provincial Key laboratory of Plant Functional Biology, College of Resources and Environmental Sciences in China Agricultural University, Beijing, 100083, China; Fujian Provincial Key Laboratory of Plant Functional Biology and College of Life Sciences, Center for Plant Water-use and Nutrition Regulation and College of Resources and Environment in Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, China.
Plant Physiol Biochem. 2020 Jun;151:429-437. doi: 10.1016/j.plaphy.2020.03.040. Epub 2020 Apr 2.
Potassium (K) has been reported to alleviate ammonium (NH) toxicity in rice through some underlying mechanisms, but it still not clear. In addition, K is an important cation for activation of plasma membrane (PM) H-ATPase activity. Here, we hypothesized that K alleviated NH toxicity by mediating PM H-ATPase function in rice root. In this study, rice plants were cultivated in hydroponic solution with various concentrations of K and NH. By concurrently supplying K with NH or re-supplying K after NH toxicity, we found that high K concentration reduced the NH uptake rate, enhanced the H extrusion rate by the roots, and alleviated rice NH toxicity. The gene expression levels of PM H-ATPase members (OsA1, 3, 7, 8, and 9) were upregulated by application of increasing concentrations of K under NH toxicity. The PM H-ATPase activity and protein expression in rice roots were also enhanced. Furthermore, the enhancement of PM H-ATPase activity by a specific stimulator (fusicoccin) rescued rice seedlings from NH toxicity. Taken together, these results indicate that K can alleviate NH toxicity, possibly by activating PM H-ATPase to extrude more H and inhibit NH uptake by root. Our results may enhance understanding of the strategy of applying K fertilizer to mitigate crop NH toxicity in agriculture.
钾（K）被报道可通过某些潜在机制缓解水稻中的铵（NH）毒性，但具体机制尚不清楚。此外，K 是激活质膜（PM）H-ATPase 活性的重要阳离子。在这里，我们假设 K 通过调节水稻根质膜 H-ATPase 功能来缓解 NH 毒性。在这项研究中，将水稻植株在含有不同浓度 K 和 NH 的水培溶液中进行培养。通过同时向 NH 中添加 K 或在 NH 毒性后重新添加 K，我们发现高浓度 K 降低了 NH 的吸收速率，增强了根的 H 外排速率，从而缓解了水稻的 NH 毒性。在 NH 毒性下，应用不同浓度的 K 可上调质膜 H-ATPase 成员（OsA1、3、7、8 和 9）的基因表达水平。水稻根中的 PM H-ATPase 活性和蛋白表达也得到增强。此外，特定刺激物（佛司可林）增强 PM H-ATPase 活性可使水稻幼苗免受 NH 毒性的影响。总之，这些结果表明，K 可以缓解 NH 毒性，可能是通过激活 PM H-ATPase 来排出更多的 H，并抑制根对 NH 的吸收。我们的结果可能有助于理解在农业中施用 K 肥以减轻作物 NH 毒性的策略。
