Involved in repair of UV radiation-induced DNA damage. Catalyzes the light-dependent monomerization (300-600 nm) of cyclobutylpyrimidine dimers (CPDs), which are formed between adjacent bases on the same DNA strand upon exposure to ultraviolet radiation. Required for plant survival in the presence of UV-B light. Not involved in the repair of (6-4) photoproducts. cyclobutadipyrimidine (in DNA) = 2 pyrimidine residues (in DNA). Binds 1 FAD per subunit. Expressed in proliferating tissues. Highly expressed in roots and shoot apical meristem (SAM). Expressed in leaves, flag leaves, and panicle. Induced by gamma irradiation. Over-expression of PHR decreases growth inhibition, leaf necrosis and CPDs accumulation under UV-B treatment. Belongs to the DNA photolyase class-2 family.