UV-B radiation in sunlight has a variety of effects on plants. The primary cause of developmental defects in plants is cyclobutane pyrimidine dimers (CPDs), which are a type of DNA damage caused by UV-B radiation. In plants, UV-B irradiation alters the expression of many genes, but it is unclear whether these changes are caused by CPD. To explore the mechanism by which CPD alters gene expression, I conduct research using model plants such as Arabidopsis, rice, and Marchantia polymorpha. UV-B is also known to alter the flowering time of plants, but the mechanism remains largely unknown. Therefore, I am investigating the molecular mechanisms by which UV-B irradiation affects flowering time in Arabidopsis. Through these studies, I hope to clarify the molecular mechanisms by which plants adapt to UV-B.