Mechanisms of Extracellular NO and Ca2+ Regulating the Growth of Wheat Seedling Roots
Mechanisms of Extracellular NO and Ca2+ Regulating the Growth of Wheat Seedling Roots
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DOI：
10.1007/s12374-010-9114-y
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发表时间：
2010-06
影响因子：
2.9
通讯作者：
Xiang Zhao;Xiaoting Zhao;Hui He;Yanxing Wang;Xiao Zhang
中科院分区：
文献类型：
--
作者：
Xiang Zhao;Xiaoting Zhao;Hui He;Yanxing Wang;Xiao Zhang
Our previous studies suggested the cross talk of nitric oxide (NO) with Ca2+in regulating stomatal movement. However, its mechanism of action is not well defined in plant roots. In this study, sodium nitroprusside (SNP, a NO donor) showed an inhibitory effect on the growth of wheat seedling roots in a dose-dependent manner, which was alleviated through reducing extracellular Ca2+concentration. Analyzing the content of Ca2+and K+in wheat seedling roots showed that SNP significantly promoted Ca2+accumulation and inhibited K+accumulation at a higher concentration of extracellular Ca2+, but SNP promoted K+accumulation in the absence of extracellular Ca2+. To gain further insights into Ca2+function in the NO-regulated growth of wheat seedling roots, we conducted the patch-clamped protoplasts of wheat seedling roots in a whole cell configuration. In the absence of extracellular Ca2+, NO activated inward-rectifying K+channels, but had little effects on outward-rectifying K+channels. In the presence of 2 mmol L−1CaCl2in the bath solution, NO significantly activated outward-rectifying K+channels, which was partially alleviated by LaCl3(a Ca2+channel inhibitor). In contrast, 2 mmol L−1CaCl2alone had little effect on inward or outward-rectifying K+channels. Thus, NO inhibits the growth of wheat seedling roots likely by promoting extracellular Ca2+influx excessively. The increase in cytosolic Ca2+appears to inhibit K+influx, promotes K+outflux across the plasma membrane, and finally reduces the content of K+in root cells.
