Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resources Sciences, Zhejiang University, Hangzhou, 310058, China; Department of Horticulture, College of Agronomy and Biotechnology, Zhejiang University, Hangzhou, 310058, China.
Plant Cell Environ. 2014 Dec;37(12):2795-813. doi: 10.1111/pce.12362. Epub 2014 May 23.
Root hairs are reported to be plastic in response to nutrient supply, but relatively little is known about their development in response to magnesium (Mg) availability. Here, we showed that development of root hairs of Arabidopsis decreased progressively with increasing Mg supply, which was related to the initiation of new trichoblast files and likelihood of trichoblasts to form hairs. Tip-focused reactive oxygen species (ROS) and cytosolic Ca(2+) concentrations [(Ca(2+) )c] during elongation of root hairs were enhanced under low Mg but decreased under high Mg. Under low Mg, application of diphenylene iodonium (DPI) or BAPTA [1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid] blocked the enhanced development of root hairs and the opposite was true when the plants under high Mg were treated with phenazine methosulphate (PMS), methyl viologen (MV) or CaCl2 . Furthermore, Mg availability did not alter root hair growth in rhd2-1 mutant that contains lower levels of ROS and cytosolic [Ca(2+) ]c. Transcriptome data and qPCR results revealed a greater fraction of morphogenetic H-genes, and cell wall organization genes were up-regulated by low Mg but down-regulated by high Mg. Our data suggest a profound effect of Mg supply on the development of root hairs in Arabidopsis, through the characterized Ca(2+) and ROS signals that modulate the elongation of root hairs and the expression of root-hair morphogenetic genes.
根毛被报道在营养供应时具有可塑性，但关于它们对镁 (Mg) 供应的反应的发育知之甚少。在这里，我们表明，随着镁供应的增加，拟南芥根毛的发育逐渐减少，这与新的生毛细胞的起始和生毛细胞形成毛的可能性有关。在伸长的根毛中，ROS 和细胞质 Ca（2+）浓度 [(Ca（2+））c] 在低镁下增强，但在高镁下降低。在低镁下，用二苯基碘（DPI）或 1,2-双（邻氨基苯氧基）乙烷-N,N,N',N'-四乙酸（BAPTA）处理会阻止根毛发育的增强，而当高镁下的植物用吩嗪甲硫磺酸（PMS）、甲紫精（MV）或 CaCl2 处理时，则反之。此外，Mg 供应不会改变 RHD2-1 突变体中根毛的生长，该突变体中 ROS 和细胞质 [Ca（2+）]c 的水平较低。转录组数据和 qPCR 结果表明，低镁上调了更多形态发生 H 基因，而细胞壁组织基因，而高镁则下调了这些基因。我们的数据表明，Mg 供应对拟南芥根毛的发育有深远的影响，通过特征化的 Ca（2+）和 ROS 信号来调节根毛的伸长和根毛形态发生基因的表达。
