Evaporative cooling signals for wound healing in plants
Repairing a damaged body part is critical for the survival of an organism. Tissue damage induces rapid responses to activate downstream events including defense, regeneration and wound healing. Despite accumulating knowledge of early wound signaling including the orchestrated actions of phytohormones, electric circus and reactive oxygen species, our knowledge about the end point of a wound response - wound healing, is still limited. We observed that a local temperature reduction associated with the activation of cold-responsive genes occurred at wounding site on Arabidopsis leaves, which was likely caused by evaporative cooling. The disappearance of localized cooling and restoration of cold responsive genes to a steady state could be used as a quantitative readout of wound healing. Based on these observations, we developed a deep learning pipeline to monitor the dynamics of wound healing. We found that CBFs transcription factors relay injury-induced cooling signal to wound healing. Thus, our work provides a tool to quantify wound healing in plants and advances our understanding of tissue repair in plants. Overall design: Arabidopsis thaliana (Col-0 ecotype) seeds were sown on Sungro Propagation Mix Question soil and placed in 4°C cold room for 3 days prior to being transferred to a short-day growth room with 23°C/19°C day/night temperatures and 45% humidity. Plants were watered weekly and placed in random block design to reduce the impact of environmental factors. Total RNA was extracted from leaf samples subjected to wounding stress. Samples were harvested at three time points: prior to the treatment (time 0), 30 minutes post-wounding, and 60 minutes post-wounding. The experiment included three biological replicates per condition.