EAGER: Breaking the walls down: Understanding the role of cell wall components in root growth regulation under water deficit conditions

该项目的总体目标是阐明玉米初生根在水分限制条件下保持生长的细胞壁组成和细胞壁力学的变化。有限的水供应是制约植物发展的一个主要环境因素，反过来又对植物表现和作物产量产生不利影响。植物对水分限制的显著反应之一是维持根的生长，使其能够从更深的土壤剖面获得水分。细胞壁组成的实质性变化与水分限制下的根的生长维持有关。然而，由于技术上的挑战，在水分限制下维持根系生长的分子和生理机制尚不清楚。这样的理解对于在正常和紧张的环境中提高作物生产力以及可持续的生物能源生产至关重要。这项研究综合了从亚细胞到器官水平的根组织反应的生化和生物力学信息，以破译细胞壁成分在调控根生长中的功能作用。成功完成这些最先进的研究将为定量分析表现出不同成分和功能特征的植物细胞壁提供概念验证。这一多学科的方法将使人们能够识别细胞壁基质中不同成分之间相互作用的设计规则，以及它们在正常和胁迫环境下对植物生长和形态发生的影响。通过该项目开发的基础知识和技术进步将通过预测植物，特别是玉米等作物如何应对气候变化，最终提高正常和压力环境下的农业生产率。该项目将为为拉美裔服务的中佛罗里达大学的一名研究生和至少两名本科生研究人员提供跨学科培训和指导，为劳动力发展做出贡献。与表现出生长抑制的地上部组织相比，玉米的初生根和节根在水分胁迫条件下优先保持生长。在初生根生长区内，顶端区域即使在严重的水分胁迫下也完全保持细胞的伸长和生长，而底部区域细胞伸长和生长减慢。这些空间差异反应与细胞壁屈服特性的变化和细胞壁组成的潜在变化有关。这个项目的总体目标是阐明使初级根在水分胁迫条件下保持生长的细胞壁组成和壁力学的变化。本研究的具体目的是首先揭示水分限制下生长的玉米初生根与充分水分下生长的初生根在生长带内细胞壁组成的差异，然后评估水分胁迫下初生根生长带细胞壁中发生的机械力化学变化，并将其与细胞壁延伸性和根的生长联系起来。将细胞壁成分分析与从亚细胞到器官水平的生化和生物力学研究相结合，将使人们能够更深入地了解植物在正常和水分有限的条件下的生长。这种多尺度的方法将揭示组件如何在细胞壁基质中相互作用，以及它们如何在水分胁迫条件下影响细胞扩张和植物生长。从长远来看，来自这些研究的知识将为有选择地改变细胞壁成分以促进植物的应激反应生长并优化它们以用于可持续食品和能源生产铺平道路。这一奖项反映了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。

The overall goal of this project is to elucidate the changes in cell wall composition and cell wall mechanics that allow maize primary roots to maintain growth under water limited conditions. Limited water availability is a major environmental factor constraining plant development, in turn adversely affecting plant performance and crop yields. One of the prominent responses of plants to water limitation is the maintenance of root growth, enabling access to water from deeper soil profiles. Substantial changes in cell wall composition are implicated in root growth maintenance under water limitation. However, due to technical challenges, the molecular and physiological mechanisms involved in root growth maintenance under water limitation remain unknown. Such understanding is critical for improving crop productivity in normal and stressful environments and for sustainable bioenergy production. This research integrates biochemical and biomechanical information from sub-cellular to organ-level responses of root tissues to decipher the functional role of cell wall components in regulating root growth. Successful completion of these state-of-the-art studies will provide proof-of-concept for quantitative analyses of plant cell walls exhibiting different compositional and functional characteristics. This multi-disciplinary approach will enable the identification of design rules for the interactions of different components within the cell wall matrix and their impacts on plant growth and morphogenesis under normal and stressful environments. The fundamental knowledge and the technological advances developed through this project will ultimately enhance agricultural productivity under normal and stressful environments by allowing predictions about how plants, especially crop plants like maize, will respond to climate change. The project will provide interdisciplinary training and mentoring for a graduate student at the University of Central Florida, an Hispanic-Serving Institution, and at least two undergraduate researchers, contributing to workforce development.Maize primary and nodal roots preferentially maintain growth under water stress conditions, compared to shoot tissues that show growth inhibition. Within the primary root growth zone, the apical region completely maintains cell elongation and growth even under severe water stress, whereas the basal region shows reduced cell elongation and growth deceleration. These spatially differential responses are associated with changes in cell wall yielding properties and potentially changes in cell wall composition. The overall goal of this project is to elucidate the changes in cell wall composition and wall mechanics that enable primary roots to maintain growth under water stress conditions. The specific objectives are to first reveal the differential cell wall compositional changes occurring within the growth zone of maize primary roots grown under water limitation compared to well-watered primary roots, and subsequently to assess the mechano-chemical changes occurring in the cell walls of the growth zone of primary roots under water stress to correlate them with cell wall extensibility and root growth. Integration of cell wall compositional analyses with biochemical and biomechanical studies from sub-cellular to organ-level scales will enable deeper understanding of plant growth under normal and water limited conditions. This multi-scale approach will unveil how components interact within the cell wall matrix and how they impact cell expansion and plant growth under water stress conditions. In the long-term, knowledge from these studies will pave the way to selectively alter cell wall components to promote stress-responsive growth in plants and optimize them for sustainable food and energy production.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.