Squalene acts as a feedback signaling molecule in facilitating bidirectional communication between tea plants

Plants respond to environmental stimuli by releasing volatile organic compounds (VOCs), which play diverse roles in plant-to-plant interactions. Previous studies have primarily focused on how receiving plants respond. However, little is known about how these receivers communicate back to the emitter plants and their subsequent impacts. Our findings indicated increased plant tolerance when neighboring plants were present, suggesting bidirectional plant communication. Furthermore, we established a model to explore the role of signals from receiver plants, identifying squalene as a crucial feedback signal enhancing the cold tolerance in emitter plants by up-regulating CsCBF5 expression. Further analysis using yeast one-hybrid analysis coupled with inhibition of brassinosteroid pathways suggested that squalene-induced castasterone (CS) accumulation directly activated CsCBF5 expression modulated by CsBES1/BZR1. Overall, these results demonstrated the role of the squalene-CS-BES1/BZR1-CBF5 pathway in the bidirectional communication between plants, expanding our understanding of plant interactions.