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.

该研究计划旨在确定植物将信号从周围环境中整合信号的机制，以控制优化其发展的增长过渡。这些机制强调了使植物在恶劣环境中定居和繁殖的进化过程。因此，研究目标将导致在挑战性的气候条件下提高植物绩效和生产力的新策略。 **我们的工作专注于理解被称为微管的动态蛋白聚合物的特性和功能。这25 nm直径的管状元素首先在50年前鉴定在植物细胞中，但现在被认为是所有真核细胞的重要组成部分，它们形成了驱动细胞分裂，生长和运动的机械。要形成这些机器，微管必须通过添加或去除称为小管蛋白的蛋白质亚基来快速生长和收缩。这些过程由微管相关蛋白控制。我们在两种此类蛋白质cLASP和MOR1上的开创性工作构成了拟议研究的基础。 * *该研究计划的一个目的是了解植物如何控制从细胞分裂到细胞延伸的过渡。我们最近发现，抗lasp蛋白是植物生长激素生长素的正常分布和活性所必需的。我们证明了携带生长素转运蛋白到微管的扣子隔室，从而防止其降解。扣子的丧失会导致细胞经历较少的分裂，并过早进入伸长阶段，从而导致细胞和矮植物较少。因此，确定如何控制扣子活动对于了解细胞如何从增殖到末端生长过渡至关重要。我们最近发现，植物类固醇激素铜氨基甲醇控制着扣扣表达，但其信号传导活性是矛盾的，由clasp控制。我们提出的剖析这种引人入胜的调节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很大的影响。 * *非生物应力和病原体极大地改变了植物的生长。微管通常会被破坏，作为适应冷，盐或暴露于重金属的压力的一部分。使用化学基因方法，我们确定了微管相关蛋白MOR1中的突变，从而改变了对高渗性应激的正常反应。我们将使用该突变体识别和操纵信号通路，使植物能够适应盐胁迫或干旱。另外，通过基因表达谱图，我们确定了13个基因，当用药物处理模拟应激诱导的微管破坏时，它们显示出改变的表达。已知其中一些基因参与病原体或非生物胁迫反应，因此将构成长期策略的基础，以提高作物植物对病原体和非生物压力的耐药性。纤维素抵抗张力的能力使其成为细胞膨胀速率和方向的关键决定因素，这对于植物性能至关重要，但对于许多工业应用至关重要。我们将使用最先进的成像技术来确定微管活性的变化如何改变纤维素的性质。 **这些旨在理解植物生长和适应的互补举措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。