Study of the Volatile Communication in Petunia relying on sesquiterpenoid-induced karrikin pathway – VOLCOM

Plants use their ability to produce volatile organic compounds (VOCs) to communicate with their environment. they are also targets of
VOCs released during plant-microbe and plant-plant interactions and within-plant self-signaling. In Petunia, we previously described
that sesquiterpenoid VOCs are emitted within the bud during flower development and airborne transported into the pistils where they
act as signals for the normal development of pistils and seed production. This phenomenon, that we called natural fumigation,
highlighted that sesquiterpenoid VOCs can have a hormone-like function in plants. In a recent study, we showed that one of these
VOCs specifically interacts with KAI2ia, an orthologue of the Karrikin insentitive 2 receptor, and activates the karrikin-like signaling
pathway shown to be crucial for the normal development of pistils. Karrikins, that contain an essential butenolide moity for bioactivity,
are assumed to be analogues of a so far unknown endogenous ligand of KAI2 receptors. Preliminary metabolomic analysis showed
that sesquiterpene derivatives originating from natural fumigation accumulate in petunia pistils. The raw formula of one of these
metabolites determined by LCMS correspond to a sesquiterpene lactone with buntaolide moiety, as confirmed by its partial purification
and structure elucidation by NMR. This molecule constitutes a putative endogenous KAI2ia ligand, chemically analogue of karrikins.
The objectives of this project are to purify, elucidate the structure and synthetize the putative KAI2ia ligand derived from fumigated
sesquiterpene VOCs, to characterize the ligand/KAI2ia complex and the downstream KAI2ia signaling pathway leading to normal pistil
development and to describe the biosynthetic pathway of the KAI2ia ligand. This project will enable to better understand mechanisms
behind plant VOC communication using sesquiterpenoid VOCs, their perception and downstream signaling.