CAREER: Permissive acidity as a regulator of plant cell expansion

职业：允许的酸度作为植物细胞扩张的调节剂

• 批准号: 2045795
• 负责人: Siobhan Braybrook
• 金额: $ 111.13万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2045795&HistoricalAwards=false
• 关键词: CAREER; Permissive; acidity; regulator; plant

Plant life is essential for the health and well-being of the planet, and all life therein. Understanding the processes that control growth in plants is therefore essential for ensuring the future of the planet and human life. In this project, the ‘acid growth’ control mechanism will be investigated in young seedlings, a key growth stage in the plant’s life that allows for emergence from the soil. Acid growth refers to a mechanism whereby the cell wall surrounding the plant cell becomes more acidic; an acidic environment activates changes in the cell wall that make it more deformable, thus allowing the plant cell it surrounds to expand and resulting in growth. The acidification of the cell wall is turned on by a plant hormone called auxin. However, too much auxin inhibits growth indicating a more complex mechanism for acid growth is at play. In this project we will extend the acid growth model to better explain the regulation of growth by auxin and wall acidity; we will investigate the possibility of a ‘permissive acidity’ for growth where the wall can be too basic and too acidic to result in growth. This project includes the development and implementation of a summer research program for incoming transfer students called ‘EMERGE’. The emerge program will have a group of five students working on a seedling growth-related research project during the summer before their junior year. The EMERGE program will provide research experience and community for incoming transfer students, key aspects for successful degree completion.The Acid Growth hypothesis was proposed over 50 years ago; it states that auxin leads to cell wall acidification which leads to wall relaxation and cell expansion. However, for almost 100 years we have known that too much auxin inhibits growth, as does too much acidity. Using the dark-grown Arabidopsis thaliana hypocotyl as a model system for elongation, we will investigate an expanded acid growth model that encompasses the concept of permissive acidity: there is an optimal acidic pH for cell growth and being too basic or too acidic may result in cessation of growth. We will quantify the relationships between cell growth, wall acidity, and auxin response during dark-grown hypocotyl elongation at both organ and cell levels. Furthermore, we will explore the quantitative relationship between growth, auxin, pH, and cell wall mechanical parameters (elasticity, viscoelasticity, and yield strength) using atomic force microscopy. We will also parameterize the pH dependent activity of several wall modifying proteins in planta. All of this data will be used to build a finite element method-based mechanical growth model of the elongating hypocotyl, instructed by an explicit auxin distribution. This project also includes a summer research on-boarding program for incoming transfer students called ‘EMERGE’. The EMERGE program will have cohorts of 5 students working on a project together each summer before traditional Fall enrollment begins in order to jump-start their research experience and education and to build community within the transfer student population within Life Sciences.This award is co-funded by the Physiological Mechanisms and Biomechanics Program and the Plant, Fungal, & Microbial Developmental Mechanisms Program in the Division of Integrative Organismal Systems, Directorate for Biological Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

植物生命对地球和地球上所有生命的健康和福祉至关重要。因此，了解控制植物生长的过程对于确保地球和人类生命的未来至关重要。在这个项目中，“酸生长”控制机制将在幼苗中进行研究，这是植物生命中的关键生长阶段，允许从土壤中出现。酸性生长是指植物细胞周围的细胞壁变得更酸的一种机制；酸性环境会激活细胞壁的变化，使其更容易变形，从而使其周围的植物细胞扩大并导致生长。细胞壁的酸化是由一种叫做生长素的植物激素引起的。然而，过多的生长素会抑制生长，这表明酸生长有更复杂的机制在起作用。在本项目中，我们将扩展酸性生长模型，以更好地解释生长素和壁酸性对生长的调节；我们将研究生长的“容许酸度”的可能性，在这种情况下，壁可能过于碱性和过于酸性而导致生长。该项目包括为即将到来的转学生制定和实施一个名为“浮现”的暑期研究计划。该项目将由五名学生组成，他们将在大三之前的夏天进行一项与幼苗生长有关的研究项目。EMERGE项目将为即将到来的转学生提供研究经验和社区，这是成功完成学位的关键方面。酸性生长假说是在50多年前提出的；它指出生长素导致细胞壁酸化，从而导致细胞壁松弛和细胞扩张。然而，近100年来，我们已经知道过多的生长素会抑制生长，过多的酸度也是如此。利用暗生长的拟南芥下胚轴作为延伸的模型系统，我们将研究一个扩展的酸生长模型，该模型包含允许酸度的概念：存在一个适合细胞生长的最佳酸性pH值，过碱性或过酸性可能导致生长停止。我们将在器官和细胞水平上量化暗生长下胚轴伸长过程中细胞生长、壁酸度和生长素反应之间的关系。此外，我们将利用原子力显微镜探索生长、生长素、pH和细胞壁力学参数（弹性、粘弹性和屈服强度）之间的定量关系。我们还将参数化植物中几种壁修饰蛋白的pH依赖性活性。所有这些数据将用于建立一个基于有限元法的下胚轴伸长的机械生长模型，该模型由明确的生长素分布指示。该项目还包括一个名为“浮现”的暑期研究项目，面向即将入学的转学生。在传统的秋季入学开始之前，每年夏天都会有5名学生一起完成一个项目，以快速启动他们的研究经验和教育，并在生命科学领域的转学生群体中建立社区。该奖项由生物科学理事会综合有机体系统部的生理机制和生物力学项目以及植物、真菌和微生物发育机制项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。