Ca²⁺ signaling is required for high ambient temperature perception in Arabidopsis thaliana

Temperature is a key environmental factor affecting plant growth and development. With the increase in global warming, it is important to understand the signal transduction pathways through which plants perceive and respond to elevated ambient temperature. Calcium (Ca²⁺) is a second messenger in various environmental stresses in plants. However, the function of Ca²⁺ in sensing elevated ambient temperature has not yet been well addressed in plants. In this study, using the Ca²⁺ sensitive aequorin reporter or GFP-based yellow cameleon 3.6 reporter in plants, we show that high temperature treatments transiently increase cytoplasmic Ca²⁺ concentration in Arabidopsis thaliana. We also found that Ca²⁺ is required for warm temperature-induced hypocotyl growth. In addition, our RNA-seq data show that transcriptional reprogramming in response to warm temperature is partially dependent on Ca²⁺. We further identified Ca²⁺ signaling-related components involved in the decoding of the response to elevated ambient temperature to support our hypothesis. Taken together, our results suggest that plants possess a Ca²⁺ signaling pathway to sense thermal changes.