REGULATING THE FLOW: Uncovering How Roots Sense and Respond to Water Availability

调节流量：揭示根部如何感知和响应水的可用性

• 批准号: BB/Z514482/1
• 负责人: POONAM MEHRA
• 金额: $ 53.54万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FZ514482%2F1
• 关键词: REGULATING; FLOW; Uncovering; How; Roots

Climate change has led to a concerning decline in soil water availability, posing a threat to both UK and global agricultural productivity. Therefore, understanding how roots sense soil water availability is vital for improving climate resilience of crops. This ambitious goal can be realised by delving into the mechanisms underlying root-soil water sensing. Notably, traditional studies on root-water interactions have focused on the whole-plant level, disregarding many water-sensing processes that occur locally in individual root tips. To address this knowledge gap, I recently developed an elegant bio-assay to study individual root tip responses to transient water stress. This bio-assay enabled me to discover the mechanistic basis of 'why roots stop branching in soil air-gaps', a phenomenon termed as 'xerobranching' (Mehra et al., 2022 Science) [1].A xerobranching response is triggered when a growing root tip loses contact with soil moisture, such as in an air-gap, leading to suppression of branching until the root tip re-enters moist soil. Recently, I discovered that xerobranching employs the water-stress hormone abscisic acid (ABA) to block root branching. ABA-driven downstream responses are triggered several hours following a xerobranching stimulus. This slow time frame is puzzling as plant roots typically detect water deficit rapidly, revealing ABA-mediated branching suppression as a 'response mechanism' rather than a primary 'water-sensing mechanism'. Hence, roots must first perceive changes in external water availability before triggering downstream ABA-regulated responses. As a Discovery fellow, I aim to uncover and characterize the early molecular events involved in 'water stress perception' during xerobranching.Ionic fluxes (such as Ca2+ and K+) are closely linked with early stages of water stress signalling. My preliminary experiments using Arabidopsis calcium-signalling mutants reveal a clear role for ionic signalling during xerobranching. Building upon these findings, I aim to investigate the functional significance of ionic fluxes in water perception by screening >80 Arabidopsis ion channel/signalling mutants using the xerobranching bio-assay (Objective 1). In addition, I aim to identify the water sensing niche in root tips by utilizing high-resolution biosensor imaging and single-cell RNA-sequencing (Objective 2). By exploiting these state-of-the-art approaches, the first phase of my project will uncover novel components involved in water perception and response. Next, I will investigate how ionic fluxes trigger ABA biosynthesis/release during xerobranching (Objective 3). Finally, Objective 4 will determine the functional relationship between ionic signalling and hydraulic fluxes using innovative cell-scale Raman-based 'water imaging' of roots. The fundamental insights arising from my research will enhance understanding about how roots perceive and respond to reduced water availability at cell-scale, laying a strong foundation for future translational efforts aimed at improving water-use-efficiency and drought tolerance of crops.Embarking on this pioneering research at the University of Nottingham (UoN), I will have the opportunity to harness a world-class research environment that offers unparalleled expertise, a cross-disciplinary collaborative culture, outstanding mentorship, and cutting-edge facilities. This will enable me to discover the fundamental mechanisms plant roots employ to sense water availability. The unwavering support of the host institution and network of leading scientists, combined with my expertise, will empower me to successfully execute this project and make a significant impact at the forefront of plant biology research. Additionally, this project will enable me to nurture a unique research vision and hone my leadership skills, equipping me to emerge as a future leader in the field of root-water interactions.

气候变化导致土壤可用水量下降，对英国和全球农业生产力构成威胁。因此，了解根系如何感知土壤水分的可用性对于提高作物的气候适应能力至关重要。这个雄心勃勃的目标可以通过深入研究根系土壤水分传感的机制来实现。值得注意的是，关于根-水相互作用的传统研究集中在整个植物水平，忽略了单个根尖局部发生的许多水感应过程。为了解决这一知识差距，我最近开发了一种优雅的生物测定法来研究个体根尖对瞬时水分胁迫的反应。这种生物测定使我能够发现“为什么根在土壤气隙中停止分枝”的机制基础，这种现象被称为“异分枝”（Mehra 等人，2022 年《科学》）[1]。当生长中的根尖失去与土壤水分的接触，例如在气隙中，导致分枝受到抑制，直到根尖重新进入潮湿的土壤。最近，我发现异分枝利用水分胁迫激素脱落酸（ABA）来阻止根分枝。 ABA 驱动的下游反应在异分支刺激后数小时被触发。这种缓慢的时间框架令人费解，因为植物根部通常会快速检测水分亏缺，这表明 ABA 介导的分枝抑制是一种“响应机制”，而不是主要的“水分感应机制”。因此，根必须首先感知外部水分可用性的变化，然后才能触发下游 ABA 调节的反应。作为一名发现研究员，我的目标是揭示和表征干分支过程中“水分胁迫感知”所涉及的早期分子事件。离子通量（例如 Ca2+ 和 K+）与水分胁迫信号传导的早期阶段密切相关。我使用拟南芥钙信号传导突变体进行的初步实验揭示了离子信号传导在异分枝过程中的明显作用。基于这些发现，我的目标是通过使用异分支生物测定筛选 > 80 个拟南芥离子通道/信号突变体来研究离子通量在水感知中的功能意义（目标 1）。此外，我的目标是利用高分辨率生物传感器成像和单细胞 RNA 测序来识别根尖中的水传感生态位（目标 2）。通过利用这些最先进的方法，我的项目的第一阶段将发现涉及水感知和响应的新颖组件。接下来，我将研究离子通量如何在异分枝过程中触发 ABA 生物合成/释放（目标 3）。最后，目标 4 将使用创新的基于细胞规模拉曼的根“水成像”来确定离子信号传导和水力通量之间的功能关系。我的研究得出的基本见解将加深对根系如何感知和应对细胞尺度可用水量减少的理解，为未来旨在提高作物用水效率和耐旱性的转化工作奠定坚实的基础。通过在诺丁汉大学 (UoN) 进行开创性研究，我将有机会利用世界一流的研究环境，该环境提供无与伦比的专业知识、跨学科合作文化、出色的指导和尖端设施。这将使我能够发现植物根部感知水分可用性的基本机制。主办机构和顶尖科学家网络的坚定支持，加上我的专业知识，将使我能够成功执行该项目，并在植物生物学研究的前沿产生重大影响。此外，这个项目将使我能够培养独特的研究视野并磨练我的领导技能，使我成为根-水相互作用领域的未来领导者。