Mitogen-activated protein kinase 6 controls root growth in Arabidopsis by modulating Ca2+-based Na+ flux in root cell under salt stress
Mitogen-activated protein kinase 6 controls root growth in Arabidopsis by modulating Ca2+-based Na+ flux in root cell under salt stress
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DOI：
10.1016/j.jplph.2013.09.023
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发表时间：
2014-03-01
影响因子：
4.3
通讯作者：
Jiang, Jing
中科院分区：
文献类型：
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作者：
Han, Shuan;Wang, Chi-wen;Jiang, Jing
丝裂原活化蛋白激酶6（MPK 6）在NaCl胁迫下Na+毒害和抑制拟南芥根生长中的作用尚不清楚。在这项研究中，我们发现，在幼苗的功能丧失突变体mpk 6 -2和mpk 6 -3的根伸长是不敏感的NaCl或Na-谷氨酸盐，但不KCl或甘露醇，与野生型（WT）幼苗相比。通过加入Ca 2+螯合剂EGTA或Ca 2+通道抑制剂LaCl 3而不是Ca 2+离子载体A23187来消除不太敏感的特征。提示mpk 6对Na+毒性的耐受性是Ca ~（2+）依赖性的。我们测量了根细胞质膜（PM）Ne传导电流（NCC）。增加浓度的NaCl增加了内向的NCCs，而减少了WT根细胞的外向NCCs，出席了一个积极的转变膜电位。在mpk 6根细胞中，NaCl显着增加向外，但不向内NCC，伴随着膜电位的负移。也就是说，mpk 6通过调节根细胞质膜Na+通量来降低NaCl诱导的Na+积累。水母发光蛋白的观察显示NaCl诱导的增加胞质Ca 2+在mpk 6根细胞，导致PM Ca 2+内流。NaCl胁迫下，mpk 6根中Na+含量和Na+/K+比值增加，而Na+/K+比值的增加则需要细胞内Ca ~（2+）的增加来缓解。总之，这些结果表明，mpk 6积累较少的Na+响应于NaCl，因为在根细胞中的胞质Ca 2+水平增加，因此，其根伸长抑制比WT的NaCl。(C)2013 Elsevier GmbH. All rights reserved.
Little is known about the role of mitogen-activated protein kinase 6 (MPK6) in Na+ toxicity and inhibition of root growth in Arabidopsis under NaCl stress. In this study, we found that root elongation in seedlings of the loss-of-function mutants mpk6-2 and mpk6-3 was less sensitive to NaCl or Na-glutamate, but not to KCl or mannitol, as compared with that of wild-type (WT) seedlings. The less sensitive characteristic was eliminated by adding the Ca2+ chelator EGTA or the Ca2+ channel inhibitor LaCl3, but not the Ca2+ ionophore A23187. This suggested that the tolerance of mpk6 to Na+ toxicity was Ca2+-dependent. We measured plasma membrane (PM) Ne-conducted currents (NCCs) in root cells. Increased concentrations of NaCl increased the inward NCCs while decreased the outward NCCs in WT root cells, attended by a positive shift in membrane potential. In mpk6 root cells, NaCl significantly increased outward but not inward NCCs, accompanied by a negative shift in membrane potential. That is, mpk6 decreased NaCl-induced the Na+ accumulation by modifying PM Na+ flux in root cells. Observations of aequorin luminescence revealed a NaCl-induced increase of cytosolic Ca2+ in mpk6 root cells, resulting from PM Ca2+ influx. An increase of cytosolic Ca2+ was required to alleviate the NaCl-increased Na+ content and Na+/K+ ratio in mpk6 roots. Together, these results show that mpk6 accumulated less Na+ in response to NaCl because of the increased cytosolic Ca2+ level in root cells; thus, its root elongation was less inhibited than that of WT by NaCl. (C) 2013 Elsevier GmbH. All rights reserved.