Xu Peipei, Fang Shan, Chen Haiying, Cai Weiming
Laboratory of Photosynthesis and Environment, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, No. 300 Fenglin Road, Shanghai, 200032, China.
Institute of Photomedicine, Shanghai Skin Disease Hospital, Tongji University School of Medicine, No. 1278 BaoDe Road, Shanghai, 200443, China.
Plant J. 2020 Sep;104(1):59-75. doi: 10.1111/tpj.14905. Epub 2020 Jul 24.
Lateral roots (LRs) are the main component of the root system architecture in Arabidopsis. The plasticity of LR development has an important role in improving plant survival in response to the external environment. Previous studies have revealed a number of genetic pathways that control plant growth in response to environmental stimuli. Here, we find that the xyloglucan endotransglucosylase 19 (XTH19) and XTH23 genes are involved in LR development under salt stress. The density of LRs was decreased in the xth23 single mutant, which was also more sensitive to salt than the wild type, and the xth19xth23 double mutant exhibited additive downregulated LR initiation and salt sensitivity compared with the single mutant. On the contrary, constitutive overexpression of XTH19 or XTH23 caused increased LR densities. Furthermore, XTH19 and XTH23 were induced by salt via the key brassinosteroid signaling pathway transcription factor BES1. In addition, we found that 35S::BES1 increased salt tolerance and the phenotype of xth19xth23 & 35S::BES1 was partially complementary to the wild-type level. In vivo and in vitro assays demonstrated that BES1 acts directly upstream of XTH19 and XTH23 to control their expression. Overall, our results revealed that XTH19 and XTH23 are involved in LR development via the BES1-dependent pathway, and contribute to LR adaptation to salt.
侧根（LRs）是拟南芥根系结构的主要组成部分。侧根发育的可塑性在提高植物对外部环境的适应性方面发挥着重要作用。此前的研究已经揭示了许多响应环境刺激控制植物生长的遗传途径。在此，我们发现木葡聚糖内转糖基酶19（XTH19）和XTH23基因参与盐胁迫下的侧根发育。xth23单突变体的侧根密度降低，其对盐的敏感性也高于野生型，并且与单突变体相比，xth19xth23双突变体表现出叠加的侧根起始下调和盐敏感性。相反，XTH19或XTH23的组成型过表达导致侧根密度增加。此外，盐通过关键的油菜素类固醇信号通路转录因子BES1诱导XTH19和XTH23。另外，我们发现35S::BES1提高了耐盐性，并且xth19xth23 & 35S::BES1的表型部分互补至野生型水平。体内和体外试验表明，BES1直接作用于XTH19和XTH23的上游以控制它们的表达。总体而言，我们的结果表明，XTHl9和XTH23通过BES1依赖性途径参与侧根发育，并有助于侧根适应盐胁迫。
