Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Jagiellońska 28, 40-032 Katowice, Poland; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic.
Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria.
Plant Sci. 2020 Apr;293:110414. doi: 10.1016/j.plantsci.2020.110414. Epub 2020 Jan 15.
The flexible development of plants is characterized by a high capacity for post-embryonic organ formation and tissue regeneration, processes, which require tightly regulated intercellular communication and coordinated tissue (re-)polarization. The phytohormone auxin, the main driver for these processes, is able to establish polarized auxin transport channels, which are characterized by the expression and polar, subcellular localization of the PIN1 auxin transport proteins. These channels are demarcating the position of future vascular strands necessary for organ formation and tissue regeneration. Major progress has been made in the last years to understand how PINs can change their polarity in different contexts and thus guide auxin flow through the plant. However, it still remains elusive how auxin mediates the establishment of auxin conducting channels and the formation of vascular tissue and which cellular processes are involved. By the means of sophisticated regeneration experiments combined with local auxin applications in Arabidopsis thaliana inflorescence stems we show that (i) PIN subcellular dynamics, (ii) PIN internalization by clathrin-mediated trafficking and (iii) an intact actin cytoskeleton required for post-endocytic trafficking are indispensable for auxin channel formation, de novo vascular formation and vascular regeneration after wounding. These observations provide novel insights into cellular mechanism of coordinated tissue polarization during auxin canalization.
植物的灵活发育的特点是具有很强的胚胎后器官形成和组织再生能力，这些过程需要紧密调节细胞间通讯和协调的组织（再）极化。植物激素生长素是这些过程的主要驱动因素，它能够建立极化的生长素运输通道，这些通道的特征是表达和极性的 PIN1 生长素运输蛋白的亚细胞定位。这些通道划定了未来器官形成和组织再生所需的血管束的位置。近年来，在理解 PIN 如何在不同的环境中改变其极性，从而引导生长素通过植物流动方面取得了重大进展。然而，生长素如何介导生长素传导通道的建立和血管组织的形成，以及涉及哪些细胞过程，仍然难以捉摸。通过结合 Arabidopsis thaliana 花序茎中复杂的再生实验和局部生长素应用，我们表明（i）PIN 亚细胞动力学、（ii）网格蛋白介导的内吞作用内化和（iii）后内吞作用所需的完整肌动蛋白细胞骨架对于生长素通道形成、新血管形成和受伤后的血管再生是必不可少的。这些观察结果为生长素通道形成过程中协调的组织极化的细胞机制提供了新的见解。
