Wang Xianling, Bi Shuangtian, Wang Lu, Li Hongpeng, Gao Bi-Ao, Huang Shanjin, Qu Xiaolu, Cheng Jianing, Wang Shucai, Liu Caiyuan, Jiang Yikuo, Zhang Bing, Liu Xiaoyu, Zhang Shaobin, Fu Ying, Zhang Zhihong, Wang Che
College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang 110866, China.
College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China.
Plant Physiol. 2020 Sep;184(1):176-193. doi: 10.1104/pp.20.00480. Epub 2020 Jul 7.
Actin binding proteins and transcription factors are essential in regulating plant root hair growth in response to various environmental stresses; however, the interaction between these two factors in regulating root hair growth remains poorly understood. Apical and subapical thick actin bundles are necessary for terminating rapid elongation of root hair cells. Here, we show that Arabidopsis () actin-bundling protein Villin1 (VLN1) decorates filaments in shank, subapical, and apical hairs. mutants displayed significantly longer hairs with longer hair growing time and defects in the thick actin bundles and bundling activities in the subapical and apical regions, whereas seedlings overexpressing showed different results. Genetic analysis showed that the transcription factor GLABRA2 (Gl2) played a regulatory role similar to that of VLN1 in hair growth and actin dynamics. Moreover, further analyses demonstrated that overexpression suppresses the mutant phenotypes regarding hair growth and actin dynamics; GL2 directly recognizes the promoter of and positively regulates expression in root hairs; and the GL2-mediated VLN1 pathway is involved in the root hair growth response to osmotic stress. Our results demonstrate that the GL2-mediated VLN1 pathway plays an important role in the root hair growth response to osmotic stress, and they describe a transcriptional mechanism that regulates actin dynamics and thereby modulates cell tip growth in response to environmental signals.
肌动蛋白结合蛋白和转录因子在调节植物根毛生长以响应各种环境胁迫方面至关重要；然而，这两种因子在调节根毛生长中的相互作用仍知之甚少。顶端和亚顶端的粗肌动蛋白束对于终止根毛细胞的快速伸长是必要的。在这里，我们表明拟南芥肌动蛋白成束蛋白绒毛蛋白1（VLN1）在柄部、亚顶端和顶端毛中修饰细丝。突变体表现出明显更长的毛，毛的生长时间更长，并且在亚顶端和顶端区域的粗肌动蛋白束和束集活性存在缺陷，而过量表达的幼苗则表现出不同的结果。遗传分析表明，转录因子GLABRA2（Gl2）在毛发生长和肌动蛋白动力学方面发挥着与VLN1类似的调节作用。此外，进一步分析表明，过量表达抑制了突变体在毛发生长和肌动蛋白动力学方面的表型；GL2直接识别的启动子并正向调节根毛中的表达；并且GL2介导的VLN1途径参与根毛对渗透胁迫的生长反应。我们的结果表明，GL2介导的VLN1途径在根毛对渗透胁迫的生长反应中起重要作用，并且它们描述了一种转录机制，该机制调节肌动蛋白动力学，从而响应环境信号调节细胞顶端生长。
