Mechanisms of heat sensing and responses in plants. It is not all about Ca<sup>2+</sup> ions

The climate shift has resulted in frequent heat waves, which cause damaging effects on plant growth and development at different life stages. All cellular processes in plants are highly sensitive to a high temperature. The plasma membrane heat receptors usually sense temperature variations directly or via a change in membrane fluidity. The accumulation of damaged proteins and reactive oxygen species also aid in heat perception. Calcium ions and heat sensors transfer signals to transcription factors through a series of signaling cascades. The heat stress transcription factors (HSFs) effectively regulate expression of heat induced genes. The members of the heat shock transcription factor A1 (HsfA1s) family are master regulators of a heat stress response. Different HSFs interact with each other at different levels and simultaneously operate heat induced gene expression. Interaction of HSFs with each other on multiple levels provides chances for manipulation to improve plant heat stress tolerance.