Regulation of root meristem differentiation by cell wall composition

植物细胞被细胞壁包围，细胞壁赋予植物结构，并具有许多功能，包括确定植物体内的最终大小和生物量。细胞壁的组成对这些重要的结构和功能角色有影响，特别是当细胞第一次生长和分化为新的细胞类型时。这是如何发生的还不是很清楚，特别是在根中，因为它不容易被研究。根细胞的生长、扩展和分化有几个因素，包括当地的土壤环境、植物内部的激素和植物中的其他发育事件。这个项目的重点是了解激素在分化过程中对根细胞壁组成的重要变化所起的作用。通过揭示根细胞中与激素作用相关的分子通路，该项目将阐明细胞壁如何对生长激素信号做出反应。了解根分化过程中细胞壁成分变化的分子基础将提供基本知识，最终可用于管理植物生长，优化生物量，确保粮食安全，并稳定植物作为国家关键的可再生资源。通过各级培训、教育和外联机会，该项目将支持指导和教育下一代科学家，包括本科生、研究生和博士后学者。胚胎后植物的发育依赖于茎和根中的分生组织种群。长期以来，人们一直认为生长素诱导的细胞壁变化介导了细胞的伸长和/或分生组织内的分裂。在初级根尖分生组织(RAM)中，生长素正向调节干细胞生态位，并影响各种前体细胞的分化，包括远端柱状细胞、侧根帽/表皮起始细胞、皮质/内胚层起始细胞和维管起始细胞。一个悬而未决的问题是，当祖细胞从静止的中心分化出来时，生长素如何调节RAM中的细胞壁属性。随着RAM细胞分化的发生，细胞壁成分是如何变化的，目前还不清楚。研究小组最近发现了一种生长素调节的半乳糖醛酸基转移酶GAUT10，它以蔗糖依赖的方式调节RAM的大小。本项目的重点是验证GAUT10在细胞壁介导的生长素调节根尖分生组织分化中起关键作用的假说。这一假说将通过三个目标进行验证：(1)确定GAUT10如何影响RAM细胞壁结构；(2)表征GAUT10如何调控根干细胞分化；(3)鉴定GAUT10如何受到根中生长素的调控。拟议的研究将产生关于生长素如何影响细胞壁特性以调节根发育的新的机制见解，使用体内、体外和电子计算机策略应用于多尺度系统，包括重组蛋白质、植物和酵母细胞以及整个拟南芥根。该项目由整合组织系统部门(IOS)发育系统集群中的植物、真菌和微生物开发计划和已建立的刺激竞争研究计划(EPSCoR)联合资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Plant cells are surrounded by cell walls that give structure to the plant and serve many functions, including determining the ultimate size and biomass of the plant body. Composition of cell walls has an impact on these important structural and functional roles, particularly when cells are first growing and differentiating into new cell types. How this occurs is not well understood, particularly in roots, which are not readily accessible for study. Several factors contribute to the growth, expansion and differentiation of root cells including the local soil environment, internal plant hormones, and other developmental events in the plant. This project focuses on understanding the role of hormones in contributing to important changes in root cell wall composition during differentiation. By uncovering the molecular pathways in root cells associated with hormone action, the project will clarify how cell walls respond to growth hormone signals. Understanding the molecular underpinnings of changes in cell wall composition during root differentiation will provide basic knowledge that can be used ultimately to manage plant growth to optimize biomass, ensure food security, and stabilize plants as critical renewable resources for the nation. Through training, education and outreach opportunities at all levels, the project will support the mentoring and education of next generation of scientists, including undergraduate, graduate students and post-doctoral scholars Post-embryonic plant development relies on meristem populations in the shoot and root. It has long been appreciated that auxin-induced changes in cell walls mediate cell elongation and/or division within meristems. In the primary root apical meristem (RAM), auxin positively regulates the stem cell niche and influences differentiation of various progenitor cells, including distal columella cells, lateral root cap/epidermal initials, cortex/endodermal initials and vasculature initials. An unanswered question is how auxin regulates cell wall properties in the RAM as progenitor cells differentiate from the quiescent center. It is not well understood how cell wall composition changes as RAM cell differentiation occurs. The research team has recently identified an auxin regulated galacturonosyltransferase, GAUT10, which regulates RAM size in a sucrose-dependent manner. This project focuses on testing the hypothesis that GAUT10 plays a key role in cell-wall-mediated auxin regulation of root apical meristem differentiation. This hypothesis will be tested by three aims: (1) Determination of how GAUT10 influences RAM cell wall structure, (2) Characterization of how GAUT10 regulates root stem cell differentiation, and (3) Identification of how GAUT10 is regulated by auxin in roots. The proposed studies will result in novel mechanistic insights regarding how auxin influences cell wall properties to regulate root development using in vivo, in vitro and in silico strategies applied to multi-scale systems, including recombinant proteins, plant and yeast cells, and whole Arabidopsis roots.This project is jointly funded by the Plant, Fungal and Microbial Development program in the Developmental Systems Cluster in the Division of Integrative Organismal Systems (IOS) and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.