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

About This Grant

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.