Collaborative Research: Deciphering the molecular mechanisms of hormone-like function of terpenoids

植物释放出种类繁多的挥发性有机化合物(VOCs)，它们在植物的生长和发育中扮演着多种角色。它们也是释放化合物的目标，作为植物-植物交流的一部分，以及植物-昆虫和植物-微生物相互作用的一部分。植物不断地暴露在大气中的VOCs中，并能够区分并对特定的提示做出反应，因此VOC感知是信息交换的重要组成部分。由于有太多的生物过程依赖于VOCs，在理解植物VOCs的生物合成及其调控以及近年来涉及VOC排放的分子机制方面取得了重大进展。然而，到目前为止，人们对植物如何感知VOCs并触发细胞反应知之甚少(S)。这个项目将描述信号通路(S)，涉及挥发性物质的感知和挥发性信号的作用方式，特别是萜类化合物，在植物生长和发育中。这项研究也将回答长期以来关于未知内源植物信号分子性质的问题(S)。这些结果将填补我们对植物嗅觉理解的重要空白，并阐明植物中挥发性感知和反应的分子机制。所获得的信息将是我们理解生态系统中植物相互作用的突破性进展，并揭示植物与动物和昆虫之间挥发性感知的差异。鉴于VOC的多功能性和对植物挥发性感知的整体缺乏了解，本研究将为代谢工程寻找新的靶点，以同时提高植物的防御能力和适应性。拟议的研究将为本科生和研究生以及博士后研究人员提供多学科培训。该教育项目还将在当地一所有少数民族学生的中学引入基于STEM的研究。其目的是提高学生对科学事业的热情、兴趣和认知。感知是植物-植物、植物-昆虫和植物-微生物相互作用的重要组成部分，但其分子机制尚不清楚。由于缺乏可靠的感知状态分子标记，使得植物信息传递的研究变得困难。最近在矮牵牛花中发现了挥发性物质通过自然熏蒸和萜类激素的类激素功能进行器官间空中运输，这为研究挥发性有机化合物的感受方式和解剖涉及的信号级联(S)提供了一个很好的平台。在矮牵牛花上的初步结果导致了一种假说，即类似karrikin的信号通路通过karrikin不敏感的受体PhKAI2ia参与感知挥发性信号，并介导依赖萜类的柱头发育。本研究将采用遗传学、分子生物学、生物化学、代谢谱、结构和细胞生物学的综合策略，(1)确定新的依赖KAI2ia的挥发性倍半萜信号通路的靶点；(2)对PhKAI2ia受体进行结构-功能分析，并阐明决定其底物特异性/选择性的分子特征；(3)确定依赖KAI2ia的倍半萜信号通路是否通过对Karikin信号至关重要的Max2泛素连接酶起作用。这项工作将揭示KAI2is在植物挥发性有机化合物感知中的未知角色(S)，阐明从生物到分子水平的KAI2is依赖的信号通路，并回答Max2泛素连接如何刻意进行配体特异性反应的问题。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。

Plants emit an amazing diversity of volatile organic compounds (VOCs) that play numerous roles in plant growth and development. They are also targets of released compounds as a part of plant-plant communication, as well as plant-insect and plant-microbe interactions. Plants are constantly exposed to atmospheric VOCs and can differentiate and respond to specific cues, therefore VOC perception is an essential part of information exchange. Due to the plethora of biological processes dependent on VOCs, significant progress has been made towards understanding the biosynthesis of plant VOCs and their regulation, and, in recent years, the molecular mechanisms involved in VOC emission. However, to date little is known about how VOCs are perceived by plants and trigger cellular response(s). This project will characterize signaling pathway(s) involved in perception of volatiles and mode of action of volatile signals, particularly terpenoids, in plant growth and development. This research will also answer the long-standing question about the nature of unknown endogenous plant signaling molecule(s). The results will fill important gaps in our understanding of plant olfaction and elucidate the molecular mechanisms underlying volatile perception and responses in plants. The obtained information will be groundbreaking for our understanding of plant interactions in the ecosystem and uncover the differences between volatile perception in plants and that in animals and insects. Given the VOC multifunctionality and overall lack of understanding of volatile perception in plants, this research will identify new targets for metabolic engineering for simultaneous improvement of plant defense and fitness. The proposed research will provide multidisciplinary training to undergraduate and graduate students, and postdoctoral researchers. The educational program will also introduce STEM-based research to a local middle school with minority students. The goals are to improve student enthusiasm, interest, and perceptions about scientific careers.Perception is an essential part of plant-plant, plant-insect and plant-microbe interactions, but the molecular mechanisms remain unknown. The absence of reliable molecular markers of the perception state makes the investigation of plant communication difficult. The recent discovery in petunia flowers of inter-organ aerial transport of volatiles via natural fumigation and hormone-like function of terpenoids, provides an excellent platform for investigating the mode of VOC perception and dissecting signaling cascade(s) involved. Preliminary results in Petunia hybrida flowers led to hypothesis that a karrikin-like signaling pathway is involved in perception of volatile signals via a karrikin-insensitive receptor, PhKAI2ia, and mediates terpene-dependent stigma development. This research will employ an integrative strategy comprised of genetics, molecular biology, biochemistry, metabolic profiling, structural and cell biology to (1) identify the targets of the new KAI2ia-dependent volatile sesquiterpene signaling pathway; (2) perform structure-functional analysis of PhKAI2ia receptor and elucidate the molecular features that determine its substrate specificity/selectivity; and (3) determine whether the KAI2ia-dependent sesquiterpene signalling pathway operates via MAX2 ubiquitin ligase essential for karrikin signaling. This work will uncover yet unknown role(s) of KAI2is in plant VOC perception, illuminate KAI2ia-dependent signaling pathway from organismal to molecular levels and answer the question of how MAX2 ubiquitin ligases deliberate ligand-specific responses.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.