Epigenetic Regulation in Plant Tolerance to Heat Stress and Thermomorphogenesis

Epigenetic modifications that cause changes in the expression of stress-responsive genes are crucial for enhancing plant tolerance to various stresses. The activation of tolerance mechanisms in plants under heat stress is heavily reliant on chromatin remodeling through DNA methylation, histone modification and histone variants. Heat stress triggers the activation of chromatin modifiers, including DNA demethylases, DNA methyltransferases, histone deacetylases, histone acetyltransferases, histone demethylases and histone methyltransferases, which coordinately induce epigenetic alterations. These modifiers act quickly leading to rapid adaptation by activating a range of transcription factors, heat shock proteins, heat shock factors and other stress-responsive genes. These alterations are essential for both the immediate stress response and also create a stress memory, which retains in a single generation or gets passed down through multiple generations. However, the mechanisms behind the transmission and preservation of this epigenetic memory in subsequent generations remain elusive. Nevertheless, this inheritance mechanism enhances the plant&s;s ability to thrive under subsequent heat stress conditions. Epigenetic regulation also contributes to thermomorphogenesis, which enhances the ability of plants to adapt to heat stress by causing different morphological changes and thereby increasing phenotypic plasticity. Gaining comprehension of these processes and their fundamental mechanisms is essential for formulating strategies to enhance crop resilience considering worldwide climate change. This chapter elaborates on the role of epigenetic regulation in enhancing plant heat stress tolerance, which becomes crucial in building up resilience against harsh environmental conditions.