Volatile communication in plants relies on a KAI2-mediated signaling pathway

Plants are targets of volatile organic compounds (VOCs) released as a part of plant-plant communication, within-plant self-signaling and plant-microbe interactions. Therefore, understanding VOC perception and downstream signaling is vital for unraveling the mechanisms behind information exchange in plants, which remain largely unexplored. Using the hormone-like function of volatile terpenoids in reproductive organ development as a system with a visual marker for communication, we demonstrated that among the four petunia karrikin-insensitive receptors, PhKAI2ia stereo-specifically perceives the (-)-germacrene D signal, triggering a karrikin-like signaling cascade. This study provides new insights into plant olfaction, uncovers the role(s) of the unique intermediate clade of KAI2 receptors, illuminates the involvement of KAI2ia-dependent signaling pathway in volatile communication and gives insight into the long-standing question about the nature of potential endogenous karrikin-like ligand(s). Overall design: Total RNA was extracted from wild type and PhTPS1 RNAi mutant pistils on day -1 and +1 postanthesis for RNA-Seq of Petunia hybrida cv. Mitchell samples.