Evolution of plant calcium and electrical signaling networks during the conquest of land

这个项目的目的是阐明植物适应胁迫的钙和电信号的功能进化对植物在旱地上的成功至关重要，以解决优先计划“Madland”中的三个悬而未决的问题：i)能够征服轮藻进化的陆地；ii)早期陆地植物进化中分子适应的演替和性质是什么；iii)对非生物和生物胁迫的耐受性的分子进化驱动因素是什么？我们将以三个模式物种--轮藻、多形地钱草和水生植物Ceratopteris richardii为例，重点讨论三种被认为提供局部信号产生和系统信号传播的离子通道类别：i)谷氨酸受体通道(GLRs)，作为钙离子的质膜进入途径和钙离子和电信号传播的介体，ii)钙激活串联孔通道1(TPC1)蛋白作为液泡电兴奋性的介体，以及iii)大钾通道(BKS)，作为连接钙和电信号的分子纽带，在藻类和早期陆地植物中表达，但在被子植物中不表达。我们将利用基因组编辑和分子遗传学，结合细胞生物学和电生理学，从功能上描述GLR、TPC和BK通道，并在植物和交叉互补研究中剖析它们在异源表达系统中的结构与功能关系。使用这种方法，我们将解决以下具体问题：i)哪些离子通道是钙和电信号转导所必需的，ii)它们在植物进化过程中是如何以及大约在何时进化的，iii)它们在不同的早期分叉植物群中的生理作用是什么，以及从具有良好特征的被子植物模型的共同祖先分别分化后，轮藻、地钱草和蕨类的功能发生了什么变化，以及iv)GLRs、TPC1和BKS的哪些结构变化提供了系统性的钙信号和电信号？

This project aims to elucidate the functional evolution of plant calcium- and electrical signaling for stress adaptation crucial for plant success on dry land, to address three outstanding questions within the Priority Programme “MAdLand”: i) which features enabling conquest of land evolved in charophyte freshwater algae, ii) what is the succession and nature of molecular adaptations in early land plant evolution, and iii) what are the molecular evolutionary drivers of tolerance to abiotic and biotic stresses?Using three model species, Chara braunii, Marchantia polymorpha and Ceratopteris richardii, we will focus on three ion channel classes considered to provide for local signal generation and systemic signal propagation: i) Glutamate receptor like channels (GLRs), as plasma membrane entry pathways for calcium ions and mediators of calcium and electrical signal propagation, ii) calcium-activated Tandem-Pore Channel 1 (TPC1) proteins as mediators of vacuolar electrical excitability, and iii) Big-K+-channels (BKs), as the putative molecular link that connects calcium- and electrical signaling, expressed in algae and early land plants but not in angiosperms.Using genome editing and molecular genetics, together with cell biology and electrophysiology, we will functionally characterize GLR, TPC and BK channels and dissect their structure-function relationships in heterologous expression systems, in planta and in cross-complementation studies. Using this approach, we will address the following specific questions: i) which ion channels are required for calcium and electrical signaling, ii) how and approximately when did they evolve during plant evolution, iii) what are their physiological roles in different early-diverging plant groups, and what functional changes occurred after the divergence of the alga Chara, the liverwort Marchantia and the fern Ceratopteris, respectively from shared common ancestors with well-characterized angiosperm models, and iv) which structural changes in GLRs, TPC1s, and BKs provided for systemic calcium- and electrical signaling?