Mechanisms of Water Sensing in Plant Roots

ongoing

Water stress is a pressing global challenge for agriculture, particularly given hostile climate change. Plants have the remarkable ability to shape their roots to forage for water. For instance, roots growing through an air-filled space (e.g., soil gap) temporarily halt branching until re-entering moist soil — an intriguing phenomenon called ‘Xerobranching’. In a recent breakthrough, I developed an elegant bio-assay to reveal how roots stop branching by employing the abscisic acid hormone when they lose contact with water (Mehra et al., 2022 Science). However, the mechanisms by which roots primarily ‘sense’ water availability is still a puzzle. My ERC project ‘Water-Blind’ is designed to unravel this mystery and discover ‘how roots sense the absence of water’ to regulate downstream branching response. Built upon my preliminary findings, I hypothesize that roots employ ionic fluxes and mechanosensing pathways to sense water. To test this hypothesis, I will pioneer first-of-its kind screening of ion channel mutants to identify ‘water-blind’ mutants, defective in water perception. Furthermore, I will uncover the underlying molecular networks responsible for this ‘water-blindness’ and ultimately, investigate the consequences of this condition on soil exploration and water foraging. To achieve these ambitious goals, I will exploit interdisciplinary state-of-the-art approaches such as next-generation X-ray computed tomography, phonon imaging, single-cell RNA sequencing and live imaging of advanced biosensors in growing roots tips. My innovative ‘real world’ approaches will generate groundbreaking insights that will significantly advance current understanding of the molecular and cellular basis of water perception in plants. The fundamental knowledge arising from this project will lay a strong foundation for future translational efforts aimed at improving water-use-efficiency and stress tolerance of crops.