Abstract: The depletion of stratospheric ozone increases the ultraviolet-B (UV-B) radiation on the earth surface, which results in multiple effects on plant, including the effects on DNA, antioxidant enzymes system, photosystem Ⅱ, and biosynthesis of protectants such as flavonoids. UV-B radiation is also an important abiotic factor. In its long-term evolution process, plant gradually forms adaptation mechanisms on UV-B radiation, which can be considered as a kind of environmental signals about the regulation of a series of gene expression processes in plant itself. In this paper, the repair of UV-B-induced DNA damage and the changes in the gene expression of antioxidant enzymes and photosystem Ⅱ in response to UV-B, as well as the studies of UV-B signal transduction, were discussed, and some issues worthy to be further studied in the plant molecular biology of UV-B radiation were put forward.

Key words: Gossypium hirsutum, Physiological development time, Simulation model