Diving Deeper: Unravelling How Plants Regulate Root Growth Angle

深入研究：揭示植物如何调节根部生长角度

• 批准号: BB/X014843/1
• 负责人: Rahul Bhosale
• 金额: $ 87.92万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX014843%2F1
• 关键词: Diving; Deeper; Unravelling; How; Plants

Limited water and nutrient availability are the major constraints for global crop production and food security. These constraints are intensifying over time given the impact of climate change on water availability and the drive to reduce fertiliser inputs to make agriculture more environmentally sustainable. Therefore, developing crops with improved nutrient and water capture efficiency could provide the solution to make significant improvements in stress resilience and yields in our crops to meet the food demand of an increasing world population. In this context, root angle is a promising root architectural trait as it critically influences nutrient and water capture from different soil profiles. For instance, steeper root angle accesses mobile water and nitrogen from deeper soils, while shallow root angle improves capture of immobile phosphorous from topsoil. Crop root systems include different root types (such as primary, seminal, lateral and crown), which grow at different angles to efficiently capture resources from different soil profiles. These different root angles are determined by gravitropic and anti-gravitropic offset (AGO) mechanisms. Previous research has uncovered many genes involved in gravitropic response machinery, however such knowledge about AGO mechanism is limited. To bridge this gap, we recently identified a novel gene (called Enhanced Gravitropism 1 i.e., EGT1) involved in AGO mechanism. A mutation within this gene causes all root types to grow only vertically downwards as it hinders their ability to maintain different growth angles. Our research further identified that mutant roots are defective in mainly two biological processes called as reactive oxygen species (ROS) maintenance and cell wall stiffness. As ROS levels in the root are known to determine cell wall's stiffness or looseness, we proposed a new AGO mechanism that EGT1 gene regulates ROS dependant cell wall stiffness to control root angle in different root types (Fusi et al., 2022. PNAS). In this BBSRC New Investigator grant we will investigate the proposed AGO mechanism in barley roots to determine how it allows different root types to grow and capture water and nutrients efficiently from different soil profiles. We will first determine where in the root (specific tissues and growth zones) EGT1 gene is transcribed and the protein is made and accumulates. We will then express EGT1 specifically in these tissues and zones in the egt1 mutant (called complementation) to confirm tissue and zone predominantly required for EGT1 function. Next, we will determine how EGT1 controls downstream targets involved in ROS and cell wall stiffness processes. Finally, we will grow the wildtype, mutant and tissue and zone-specific complementation lines under water, nutrient and high temperature stress conditions to understand how this AGO mechanism is used by plant to change root angle in response to these conditions. We will also uncover whether change in angle in the mutant vs wildtype and complementation line roots are better able to grow under these abiotic stress conditions.The knowledge gained in this study will provide vital new information about EGT1 and its key downstream targets involved in AGO mechanism and controlling root angle in response to environmental cues. This will help breeders to design novel approaches to enhance resource capture and improve yield in crops, supporting efforts to improve food security in the UK and worldwide. The remit of our project thus falls under a strategic priority area supported by the BBSRC Bioscience for Sustainable Agriculture and Food.

有限的水和养分供应是全球作物生产和粮食安全的主要制约因素。鉴于气候变化对水资源供应的影响以及减少化肥投入以使农业在环境上更加可持续的努力，这些限制随着时间的推移而加剧。因此，开发具有更高养分和水分捕获效率的作物可以提供显着提高作物抗逆能力和产量的解决方案，以满足不断增长的世界人口的粮食需求。在这种情况下，根角是一种很有前途的根系结构特征，因为它对不同土壤剖面的养分和水分捕获具有至关重要的影响。例如，较陡的根角可以从较深的土壤中获取流动的水和氮，而较浅的根角可以改善从表土中捕获固定的磷。作物根系包括不同的根系类型（如初生根、种子根、侧根根和冠根），它们以不同的角度生长，以有效地从不同的土壤剖面中捕获资源。这些不同的根部角度由向地性和反向地性偏移（AGO）机制决定。先前的研究已经发现了许多与向地反应机制有关的基因，但是关于 AGO 机制的了解是有限的。为了弥补这一差距，我们最近发现了一个参与 AGO 机制的新基因（称为增强向地性 1，即 EGT1）。该基因内的突变导致所有根类型仅垂直向下生长，因为它阻碍了它们保持不同生长角度的能力。我们的研究进一步发现，突变根主要在活性氧（ROS）维持和细胞壁硬度这两个生物过程中存在缺陷。由于已知根中的 ROS 水平决定细胞壁的刚度或松散度，我们提出了一种新的 AGO 机制，即 EGT1 基因调节 ROS 依赖性细胞壁刚度，以控制不同根类型的根角度 (Fusi et al., 2022. PNAS)。在 BBSRC 新研究员资助中，我们将研究大麦根中拟议的 AGO 机制，以确定它如何允许不同的根类型生长并从不同的土壤剖面中有效地捕获水分和养分。我们将首先确定 EGT1 基因在根部（特定组织和生长区域）的哪个位置进行转录以及蛋白质的生成和积累。然后，我们将在egt1突变体的这些组织和区域中特异性表达EGT1（称为互补），以确认EGT1功能主要所需的组织和区域。接下来，我们将确定 EGT1 如何控制参与 ROS 和细胞壁硬度过程的下游靶点。最后，我们将在水、营养和高温胁迫条件下培养野生型、突变体以及组织和区域特异性互补系，以了解植物如何利用这种 AGO 机制来改变根部角度以响应这些条件。我们还将揭示突变体与野生型和互补系根部的角度变化是否能够在这些非生物胁迫条件下更好地生长。本研究中获得的知识将提供有关 EGT1 及其参与 AGO 机制的关键下游靶标的重要新信息并根据环境线索控制根部角度。这将帮助育种者设计新的方法来加强资源捕获和提高作物产量，支持改善英国和世界各地粮食安全的努力。因此，我们项目的职责属于 BBSRC 可持续农业和食品生物科学支持的战略优先领域。