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

随着气候的变化，干旱已成为损害全球农作物生产力的主要环境威胁。气孔，陆地植物叶表面的微孔，可以打开和关闭，允许进入叶子的二氧化碳和水蒸气逃逸。据估计，通过这些结构的水分蒸发可以解释超过90%的植物水分损失。因此，对植物如何应对干旱以调节水分损失的详细了解可以为减少干旱造成的作物损失提供方法。气孔导度是通过气孔交换二氧化碳或水蒸气的总体指标；它既与气孔的数量有关，也与气孔的开放程度有关，因此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经被广泛研究，但ABA信号植物增加或减少气孔数量的机制仍然不清楚。本研究旨在通过研究ABA在气孔形成中的作用，为深入了解植物的抗旱性提供依据。大部分研究将由四名来自贫困社区的本科生进行。这些学生将由PI和一名研究生指导，并将相互充当同行导师。在这项研究中产生的基因工程植物的生产及其表型分析，将作为开发一门新的本科实验室课程的基础。学习这门课程的学生将接受一整套广泛使用的技术的广泛实践培训，这将提高他们的科学认同感，并为他们的职业STEM职业生涯做好更好的准备。PI的团队已经发现了一种耐旱突变株，它在干旱条件下比充分浇水时形成气孔的速度更慢。对该突变体在干旱胁迫下的分析表明，ABA信号被增强，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来介导干旱引发的气孔抑制。这一假说将通过两个目的来验证：1)检测ABA在干旱引发的气孔抑制中的作用；(2)确定ABA信号靶向的转录因子在突变体的气孔发育途径中。这一结果有可能为干旱如何控制气孔数量提供新的见解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.