Chai Sen, Li En, Zhang Yan, Li Sha
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
Front Plant Sci. 2020 Jun 4;11:671. doi: 10.3389/fpls.2020.00671. eCollection 2020.
Asymmetric root growth (ARG) on tilted plates, or root coiling on horizontally placed plates, is proposed to be a combination of gravitropism, mechanical sensing, and "circumnutation," a word designated by Charles Darwin to describe the helical movement that all plant organs make around the growth direction. ARG is developmentally controlled in which microtubule-regulating proteins and the phytohormone auxin participates. Nutrient deficiency influences ARG. However, it is unclear which nutrients play key roles in regulating ARG, what endogenous components are involved in responding to nutrient deficiency for ARG, and how nutrient deficiency is translated into endogenous responses. We report here that nitrate deficiency resulted in a strong ARG in Arabidopsis. Nitrate deficiency caused root coiling on horizontal plates, which is inhibited by an auxin transport inhibitor, and by mutations in () and (). We further show that suppression of ARG by nitrate is mediated by the nitrate transporter/sensor NRT1.1. In addition, PIN2- and AUX1-mediated auxin transports are epistatic to NRT1.1 in nitrate deficiency-induced ARG. This study reveals a signaling pathway in root growth by responding to exogenous nitrate and relaying it into altered auxin transport.
倾斜平板上的不对称根生长（ARG），或水平放置平板上的根卷曲，被认为是重力作用、机械感应和“回旋转头运动”的组合，“回旋转头运动”是查尔斯·达尔文用来描述所有植物器官围绕生长方向进行的螺旋运动的术语。ARG受发育调控，其中微管调节蛋白和植物激素生长素参与其中。营养缺乏会影响ARG。然而，尚不清楚哪些营养物质在调节ARG中起关键作用，哪些内源性成分参与对ARG营养缺乏的响应，以及营养缺乏如何转化为内源性反应。我们在此报告，硝酸盐缺乏导致拟南芥中强烈的ARG。硝酸盐缺乏导致水平平板上的根卷曲，这被生长素运输抑制剂以及（）和（）中的突变所抑制。我们进一步表明，硝酸盐对ARG的抑制作用由硝酸盐转运体/传感器NRT1.1介导。此外，在硝酸盐缺乏诱导的ARG中，PIN2和AUX1介导的生长素运输对NRT1.1呈上位性。这项研究揭示了根生长中通过对外源硝酸盐作出反应并将其转化为生长素运输改变的信号通路。
