Dissecting brassinosteroid signaling mediated regulation of root growth angle in wheat

剖析油菜素类固醇信号介导的小麦根生长角调节

• 批准号: 2746359
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2746359
• 关键词: Dissecting; brassinosteroid; signaling; mediated; regulation

RGA of different root-types (primary, seminal and crown) are often distinct to limit competition and are referred to as gravitropic setpoint angle (GSA). The vertical GSA of primary roots is maintained by the positive gravitropic mechanism, while non-vertical GSA in other root-types is determined by competing gravitropic and anti-gravitropic offset (AGO) mechanisms. Although past research in the model plant Arabidopsis unraveled gravitropic mechanisms, understanding of AGO mechanisms remains limited as crucial root-types (seminal and crown) do not exist in Arabidopsis. Moreover, these mechanisms remain largely unexplored in crops due to limited genetic resources. Wheat, an important crop for the UK and world, represents an ideal system for studying RGA as all root-types are easily distinguiishable and have available genetic and genomic resources. Recently, we screened various wheat phytohormone signaling mutants (auxin, ethylene, brassinosteroid and bibberellin) for RGA and observed that BR signaling mutants (prominently for tabri1) show significantly steeper seminal and crown roots compared to wildtype.Aim:In this project, we will determine the molecular mechanisms by which brassinosteroids control RGA in wheat.Work Plan:Do other Brassinosteroid pathway genes regulate RGA? (Year1) tabri1 (A-homeologue) showed >30% steeper seminal and crown RGA than the wildtype. We will phenotype remaining single tabri1 mutants (of B- and D-homeologues) and their combinatorial double and triple mutants and assess if the observed tabri1 pheotype is specific to A-homeolgoue or enhanced by stacking mutations in other TaBRI1 homeologues. Additionally, we will screen other available brassinosteroid signaling, biosynthetic and receptor mutants for RGA phenotype using vertical and 90 gravistmulus.Where does TaBR1-dependant RGA regulation takes place? (Year1-2)We will investigate where TaBRI1 is made in the wheat root and functions to control RGA by tagging the BRI1 protein with green fluorescent protein (GFP), then putting this transgene into tabri1 plants to test if it can rescue the mutant and reveal its location of expression.Explore the genetic diversity of BR signaling and RGA in Watkins collection (Year3)We are currently screening >800 lines from a wheat population for RGA phenotype. Using bioinformatics pipeline, we will investigate how much natural variation of RGA is explained by the polymorphism within the TaBR1. This analyss will help link the ancestory, habitat and environmental conditions from which these lines were collected and generate further testable hypothesis.What downstream components TaBR1 regulate to control RGA? (Year3-4)Extract RNA from root samples of WT and single or higher order Tabri1 mutants growing under vertical and gravistimulus conditions and perform RNAseq analysis to determine key differentially expressed genes and their enriched processes involved during BRI1 mediated RGA control. What is the relevane of TaBR1 mediated RGA? (Year4)Nutrient, water and heat stresses are known to influence RGA to optimise capture of soil resources. We will perform growth-room, glasshouse and field experiments on mutants and WT under control and stress coditions and assess the RGA, root and shoot biomass and grain yield. Output: Improved understanding of molecular mechanisms controlling RGA will guide selection of alleles that can be exploited through DFW breeders toolkit.

不同根类型（原根、种子和树冠）的RGA通常是不同的，以限制竞争，并被称为向地性设定值角（GSA）。原生根的垂直GSA由正向地机制维持，而其他类型根系的非垂直GSA则由向地和反向地抵消（AGO）机制决定。虽然过去对模式植物拟南芥的研究揭示了向地性机制，但对AGO机制的理解仍然有限，因为关键的根类型（种子和冠）在拟南芥中不存在。此外，由于遗传资源有限，这些机制在很大程度上尚未在作物中得到探索。小麦是英国和世界上重要的作物，它是研究RGA的理想系统，因为所有的根系类型都很容易区分，并且具有可用的遗传和基因组资源。最近，我们筛选了多种小麦植物激素信号突变体（生长素、乙烯、油菜素内酯和bibberellin）用于RGA，并观察到BR信号突变体（尤其是tabri1）与野生型相比，具有明显更陡峭的种子和冠根。目的：在本项目中，我们将确定油菜素内酯控制小麦RGA的分子机制。工作计划：其他油菜素内酯途径基因是否调控RGA？（Year1） tabri1 （a同源基因）的种子和冠RGA比野生型陡30%。我们将对剩余的单tabri1突变体（B和d同源物）及其组合的双突变体和三突变体进行表型分析，并评估观察到的tabri1表型是否仅针对a同源物，还是通过堆叠其他tabri1同源物的突变而增强。此外，我们将筛选其他可用的油菜素内酯信号，生物合成和受体突变体的RGA表型使用垂直和90重力。依赖tabr1的RGA调控发生在哪里？我们将通过绿色荧光蛋白（GFP）标记BRI1蛋白，然后将该转基因放入TaBRI1植株中，测试它是否可以拯救突变体并揭示其表达位置，来研究TaBRI1在小麦根系中的合成位置和控制RGA的功能。我们目前正在从一个小麦群体中筛选近800个品系的RGA表型。利用生物信息学管道，我们将研究RGA的自然变异有多少是由TaBR1内的多态性解释的。这种分析将有助于将收集到的这些品系的祖先、栖息地和环境条件联系起来，并产生进一步可验证的假设。TaBR1调控哪些下游成分来控制RGA？（3-4年）从垂直和重力条件下生长的WT和单阶或高阶Tabri1突变体的根样品中提取RNA，并进行RNAseq分析，以确定BRI1介导的RGA控制中涉及的关键差异表达基因及其富集过程。TaBR1介导的RGA的相关性是什么？(4)已知养分、水和热胁迫会影响RGA以优化土壤资源的捕获。我们将在控制和胁迫条件下对突变体和WT进行生长室内、温室和田间试验，评估RGA、根冠生物量和籽粒产量。成果：提高对控制RGA的分子机制的理解将指导可以通过DFW育种工具包开发的等位基因的选择。