BRC-BIO: Investigation of the role of the plant hormone, abscisic acid, in stomatal formation using a novel drought-tolerant mutant

随着气候变化，干旱已成为影响全球作物生产力的主要环境威胁。气孔，陆生植物叶片表面的微孔，可以打开和关闭，让二氧化碳进入叶片和水蒸气逸出。据估计，通过这些结构的水分蒸发可以解释90%以上的植物水分流失。因此，详细了解植物如何对干旱作出反应以调节水分流失，可以为减少干旱造成的作物损失的方法提供信息。气孔导度是对二氧化碳或水蒸气通过气孔交换的全面测量；它对气孔的数量和开放程度都有反应，从而提供了干旱胁迫的指标。植物激素脱落酸（ABA）是一种胁迫相关激素，通过调节气孔导度直接响应干旱胁迫。虽然ABA在气孔关闭信号中的作用已被广泛探索，但ABA如何信号植物增加或减少气孔数量的机制尚不清楚。本研究旨在通过探索ABA在气孔形成中的作用，为了解植物的耐旱性提供依据。大部分研究将由来自服务欠缺社区的四名本科生进行。这些学生将由PI和一名研究生指导，并将作为彼此的同伴导师。本研究中产生的基因工程植物的生产及其表型分析将作为开发新的本科实验课程的基础。参加本课程的学生将接受广泛的实践培训，掌握一整套广泛使用的技术，这将提高他们的科学身份，并为他们的专业STEM职业生涯做好更好的准备。PI的研究小组已经发现了一种耐旱突变体，它在干旱条件下比在水分充足的情况下产生气孔的速度要慢。对干旱胁迫下突变体的分析表明，ABA信号增强，促进气孔形成的转录因子被优先抑制。PI假设ABA通过靶向突变体中的气孔相关转录因子介导干旱引发的气孔抑制。这一假设将通过两个目标来验证：1)研究ABA在干旱触发的突变体气孔抑制中的作用；(2)在突变体气孔发育途径中确定ABA信号靶向的转录因子。这些结果有可能为干旱如何控制气孔数量提供新的见解。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。

In the wake of changing climate, drought has become a major environmental threat that impairs crop productivity worldwide. Stomata, micro-pores on the leaf surfaces of terrestrial plants, can open and close to allow carbon dioxide into the leaf and water vapor to escape. Water evaporation via these structures is estimated to explain over 90% of water loss from plants. Thus, a detailed understanding of how plants respond to drought to mediate water loss can inform approaches to reduce crop loss due to drought. Stomatal conductance is an overall measure of the exchange of carbon dioxide or water vapor via the stomata; it responds to both the number of stomata and how open they are, thus providing an indicator of drought stress. The plant hormone abscisic acid (ABA) is a stress-related hormone that directly responds to drought stress by regulating stomatal conductance. While the role of ABA in signaling stomata to close has been extensively explored, the mechanisms by which ABA signals the plant to increase or decrease the number of stomata remains elusive. The research aims of this study are designed to provide insight into plant drought tolerance by exploring the ABA function in stomatal formation. Much of the research will be conducted by four undergraduate students from underserved communities. These students will be mentored by the PI and a graduate student and will serve as peer mentors to each other. Production of the genetically engineered plants generated in this study, and the phenotypic analyses thereof, will serve as the basis for development of a new undergraduate laboratory course. Students taking this course will receive extensive hands-on training in a complete set of widely used techniques, which will promote their science identity and better prepare them for professional STEM careers.The PI’s group has identified a drought-tolerant mutant, which produces stomata more slowly under drought conditions than when well-watered. Analysis of the mutant under drought stress has revealed that ABA signaling is enhanced and a transcription factor that promotes stomatal formation is preferentially inhibited. The PI hypothesizes that ABA mediates drought-triggered stomatal inhibition by targeting stomatal-associated transcription factors in the mutant. This hypothesis will be tested by two aims to: 1) examine the role of ABA in drought-triggered stomatal inhibition in the mutant, and (2) identify the transcription factor targeted by the ABA signal in the stomatal developmental pathway in the mutant. The results have the potential to provide new insights into how drought controls stomatal numbers.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.