Wang Peng, Wan Ning, Horst Walter J, Yang Zhong-Bao
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Science, Shandong University (Qingdao), Qingdao 266237, PR China.
Institute of Plant Nutrition, Leibniz Universität Hannover, Herrenhaeuser Str. 2, D-30419 Hannover, Germany.
J Exp Bot. 2023 Mar 13;74(5):1358-1371. doi: 10.1093/jxb/erac516.
Aluminium (Al) toxicity is one of the major constraints for crop growth and productivity in most of the acid soils worldwide. The primary lesion of Al toxicity is the rapid inhibition of root elongation. The root apex, especially the transition zone (TZ), has been identified as the major site of Al accumulation and injury. The signalling, in particular through phytohormones in the root apex TZ in response to Al stress, has been reported to play crucial roles in the regulation of Al-induced root growth inhibition. The binding of Al in the root apoplast is the initial event leading to inhibition of root elongation. Much progress has been made during recent years in understanding the molecular functions of cell wall modification and Al resistance-related genes in Al resistance or toxicity, and several signals including phytohormones, Ca2+, etc. have been reported to be involved in these processes. Here we summarize the recent advances in the understanding of Al-induced signalling and regulatory networks in the root apex involved in the regulation of Al-induced inhibition of root growth and Al toxicity/resistance. This knowledge provides novel insights into how Al-induced signals are recognized by root apical cells, transmitted from the apoplast to symplast, and finally initiate the defence system against Al. We conclude that the apoplast plays a decisive role in sensing and transmitting the Al-induced signals into the symplast, further stimulating a series of cellular responses (e.g. exudation of organic acid anions from roots) to adapt to the stress. We expect to stimulate new research by focusing on the signalling events in the root apex in response to Al stress, particularly taking into consideration the signal transduction between the meristem zone, TZ, and elongation zone and the apoplast and symplast.
铝（Al）毒性是全球大多数酸性土壤中作物生长和生产力的主要限制因素之一。铝毒性的主要损害是对根伸长的快速抑制。根尖，尤其是过渡区（TZ），已被确定为铝积累和损伤的主要部位。据报道，信号传导，特别是通过根尖过渡区的植物激素对铝胁迫的响应，在调节铝诱导的根生长抑制中起关键作用。铝在根质外体中的结合是导致根伸长抑制的初始事件。近年来，在理解细胞壁修饰和铝抗性相关基因在铝抗性或毒性中的分子功能方面取得了很大进展，并且据报道包括植物激素、Ca2+等在内的几种信号参与了这些过程。在这里，我们总结了在理解根尖中铝诱导的信号传导和调控网络方面的最新进展，这些网络参与了铝诱导的根生长抑制和铝毒性/抗性的调节。这些知识为根尖细胞如何识别铝诱导的信号、从质外体传递到共质体以及最终启动针对铝的防御系统提供了新的见解。我们得出结论，质外体在感知铝诱导的信号并将其传递到共质体中起决定性作用，进一步刺激一系列细胞反应（例如从根中分泌有机酸阴离子）以适应胁迫。我们期望通过关注根尖对铝胁迫的信号事件来激发新的研究，特别是考虑到分生组织区、过渡区和伸长区之间以及质外体和共质体之间的信号转导。
