The Shape of Plants: Microtubule Dynamics and Plant Adaptation

植物的形状：微管动力学和植物适应

• 批准号: RGPIN-2014-06080
• 负责人: Wasteneys, Geoffrey
• 金额: $ 9.25万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=668233
• 关键词: Shape; Plants; Microtubule; Dynamics; Plant

This research program aims to identify the mechanisms by which plants integrate signals from their immediate surroundings to control the growth transitions that optimize their development. These mechanisms underline the evolutionary processes that have enabled plants to colonize and thrive in harsh environments. The research objectives will therefore lead to new strategies for enhancing plant performance and productivity under challenging climatic conditions. **Our work focuses on understanding the properties and function of dynamic protein polymers known as microtubules. These 25 nm diameter tubular elements were first identified 50 years ago in plant cells but are now recognized as essential components of all eukaryotic cells in which they form the machinery that drives cell division, growth and motility. To form these machines, microtubules must undergo rapid growth and shrinkage through addition or removal of protein subunits known as tubulins. These processes are controlled by microtubule-associated proteins. Our pioneering work on two such proteins, CLASP and MOR1, form the foundation for the proposed research.* *One objective of this research program is to understand how plants control the transition from cell division to cell elongation. We recently discovered that the CLASP protein is required for normal distribution and activity of the plant growth hormone auxin. We demonstrated that CLASP tethers compartments carrying auxin transporters to microtubules, thus preventing their degradation. Loss of CLASP causes cells to undergo fewer rounds of division and to enter the elongation phase prematurely, resulting in fewer cells and dwarf plants. Determining how CLASP activity is governed is therefore critical for understanding how cells transition from proliferation to terminal growth. We have recently found that the plant steroid hormone brassinolide controls CLASP expression but that its signaling activities are, paradoxically, controlled by CLASP. Our proposed strategies to dissect this fascinating regulatory feedback mechanism will have far reaching implications for understanding how hormone-based signaling networks optimize plant growth.* *Abiotic stresses and pathogens dramatically alter plant growth. Microtubules are often disrupted as part of the adaptation to stresses such as cold, salt or exposure to heavy metals. Using a chemical-genetics approach, we identified a mutation in the microtubule-associated protein MOR1 that alters the normal response to hyperosmotic stress. We will use this mutant to identify and manipulate the signaling pathways that enable plants to adapt to salt stress or drought. In addition, through a gene expression profiling initiative, we identified 13 genes that show altered expression when treated with a drug that simulates stress-induced microtubule disruption. Some of these genes are known to be involved in pathogen or abiotic stress responses and will therefore form the foundation of a long-term strategy to improve resistance of crop plants to pathogens and abiotic stress.**Our third goal will refine the understanding of how microtubules control the enzyme complexes that produce the world's most abundant biopolymer cellulose. The ability of cellulose to resist tension makes it a key determinant of both the rate and direction of cell expansion, which is critical for plant performance but also of relevance for many industrial applications. We will use state-of-the-art imaging technology to determine how changes in microtubule activity alter the properties of cellulose. **These complementary initiatives aimed at understanding plant growth and adaptation will address critical issues facing agriculture and forestry, and provide opportunities for the biofuels industry.

这项研究计划旨在确定植物整合来自其周围环境的信号以控制生长转换以优化其发育的机制。这些机制突显了使植物能够在恶劣环境中定居和茁壮成长的进化过程。因此，研究目标将导致在具有挑战性的气候条件下提高植物表现和生产力的新战略。**我们的工作重点是了解称为微管的动态蛋白质聚合物的特性和功能。这些直径25 nm的管状元件在50年前首次在植物细胞中被发现，但现在被认为是所有真核细胞的重要组成部分，在这些细胞中，它们形成了驱动细胞分裂、生长和运动的机制。为了形成这些机器，微管必须经历快速生长和收缩，通过添加或移除称为微管蛋白的蛋白质亚单位。这些过程是由微管相关蛋白控制的。我们在两种这样的蛋白质CLASP和MOR1上的开创性工作为拟议的研究奠定了基础。**该研究计划的一个目标是了解植物如何控制从细胞分裂到细胞伸长的转变。我们最近发现，CLAP蛋白是植物生长激素生长素正常分布和活性所必需的。我们证明，CLAP将携带生长素转运蛋白的隔室系系到微管，从而防止它们的降解。失去卡环会导致细胞分裂次数减少，并提前进入伸长阶段，导致细胞减少和植株矮化。因此，确定CLASP活性是如何调控的，对于理解细胞如何从增殖过渡到终端生长至关重要。我们最近发现，植物类固醇激素油菜素内酯控制CLAP的表达，但矛盾的是，它的信号活性是由CLAP控制的。我们提出的剖析这一有趣的调控反馈机制的策略，将对理解基于激素的信号网络如何优化植物生长具有深远的影响。**非生物胁迫和病原体极大地改变了植物的生长。微管经常被破坏，作为对寒冷、盐分或重金属暴露等压力适应的一部分。利用化学遗传学方法，我们确定了微管相关蛋白MOR1中的一个突变，该突变改变了对高渗应激的正常反应。我们将使用这个突变体来识别和操纵使植物适应盐胁迫或干旱的信号通路。此外，通过基因表达谱倡议，我们识别了13个基因，这些基因在用一种模拟应激诱导的微管破坏的药物治疗时表现出表达变化。其中一些基因已知参与病原体或非生物胁迫反应，因此将形成提高作物对病原体和非生物胁迫抵抗力的长期战略的基础。**我们的第三个目标将完善对微管如何控制酶复合体的理解，这些酶复合体产生世界上最丰富的生物聚合物纤维素。纤维素抵抗张力的能力使其成为细胞扩张速度和方向的关键决定因素，这对植物的表现至关重要，但也与许多工业应用相关。我们将使用最先进的成像技术来确定微管活动的变化如何改变纤维素的性质。**这些旨在了解植物生长和适应的补充倡议将解决农业和林业面临的关键问题，并为生物燃料行业提供机会。