EAGER:Novel approaches to study green leaf volatile perception

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Plants that are injured by herbivores emit volatile organic compounds (VOC) into the airspace which can be perceived by neighboring plants. These plants interpret the volatile compounds as alarm signals and start to upregulate defense responses against their enemies to be prepared for an impending attack. Effects of volatile compounds as inducers of defenses are well characterized, but it is unknown how plants perceive them. In general, alarm signals are perceived by dedicated receptor proteins. Most herbivore-induced volatile compounds are very small and difficult to track, which impedes the identification of their receptors. This project will develop a novel approach for labeling volatile compounds with very small tags that can be used to track the compounds and thus identify their receptors. The tagging strategy can be adapted for other small infochemicals and thus transform our knowledge of communication in plants. Identification of receptor proteins for volatile alarm signals may help to devise novel strategies for sustainable crop production by relying on innate plant defenses rather than agrochemicals. Aspects of this project will also be incorporated into an Ecology and Evolution laboratory class. In addition, undergraduates from groups underrepresented in STEM disciplines will be actively recruited to provide extra-curricular experiential learning opportunities. These students will work on VOC signaling related to this project. This will develop their practical, analytical, and communication skills, which prepares them for professional careers. In addition, two graduate students will be trained in biology and chemistry to provide a cutting-edge interdisciplinary education in chemical ecology and molecular biochemistry.Many aspects of plant communication are mediated by volatile organic compounds such as green leaf volatiles (GLVs). When plants are injured by herbivores, they emit GLVs, which can be perceived not only by distant parts of the wounded plants (within-plant communication) but also by neighboring plants (interplant communication). Perception of these GLVs is interpreted by receiver tissues as a sign of imminent danger and results in priming or upregulation of defense responses. The objective of this EAGER proposal is to advance novel approaches to identify GLV receptor proteins that initiate defense signaling. Very small non-proteinaceous ligands like GLVs (containing only six or eight carbons) are difficult to tag and to track. This proposal takes a novel approach by using ‘click chemistry’ to couple bioactive minitagged GLVs to reporter tags in order to identify receptor proteins for GLVs. Reporters that emit fluorescent light will be used to localize the receptor-GLV-reporter complex, and biotin-based reporter tags will be used to purify this complex and to isolate a GLV receptor. Additionally, GLV-induced rapid phosphorylation-based signaling events will be determined by a phosphoproteomics approach to identify early GLV-responsive signaling proteins such as GLV receptors. Although the role of GLVs in plant communication is well documented, it is completely unknown how they are perceived by plants. This is a significant knowledge gap that hampers our understanding of GLV signaling and function. Identification and characterization of GLV receptors would transform our understanding of plant communication at the molecular and ecological level.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.