Epigenetic Memory of Ultraviolet and Light Stress in Plants

Ultraviolet (UV) ray is one of the major light cues that plants are constantly exposed to, and it has a huge impact on the pattern of their growth, development and response to stress. While photosynthesis and photomorphogenesis depend on light, excessive UV radiation damages DNA, causes oxidative stress and changes several functions of cells. In order to reduce UV-induced damage, plants have developed complex defense mechanisms that include chromatin changes and epigenetic control to create stress memory. Modulating transcriptional responses to UV exposure is mostly dependent on epigenetic mechanisms, including DNA methylation and histone changes. Histone acetylation and chromatin remodeling, triggered by oxidative DNA damage and production of cyclobutane pyrimidine dimers (CPDs), promote effective DNA repair. Moreover, transcriptional reprogramming and homologous recombination rates are impacted by stress-induced modifications in DNA methylation patterns, which affect genomic stability and adaptive responses. Recent research shows that plants have three different timeframes of epigenetic stress memory: transgenerational memory, which endures across generations, short-term transcriptional memory and long-term stress memory that is mitotically heritable. The way UV stress interacts with other abiotic stressors like temperature, salinity and drought highlights how epigenetic mechanisms play a comprehensive role in plant adaptation. Jasmonic acid and abscisic acid are two examples of phytohormones that interact to modify epigenetic responses and enhance stress tolerance. The development of UV-tolerant crops is made possible by developments in epigenetic engineering, such as chromatin changes mediated by CRISPR-Cas9. Understanding the molecular underpinnings of epigenetic inheritance and using epigenomic technologies to improve agricultural sustainability in the face of climate change should be one of the main goals of future research.