Abstract

Ultraviolet-B (UV-B) has been confirmed to be harmful to living organisms and it is of concern that the amount of UV-B radiation reaching the earth’s surface is increasing because of the depletion of the stratospheric ozone layer. Effect of different levels of tea catechins on morphological damage and expression of chalcone synthase gene in Arabidopsis thaliana plants exposed to UV-B were investigated. Tea catechins at levels 250 - 1000 mgL^-1 screened off UV-B resulting in less expression of chalcone synthase gene and lighter stress of the UV-B exposed plant. The application of tea catechins was propitious to the recovery of the UV-B damaged plants, especially at concentration 250 mg L^-1. The protective mechanism of tea catechins against UV-B stress is considered to be their sunscreen property instead of their free radical scavenging and antioxidant properties.

Key words: Tea catechins, Arabidopsis, UV-B, chalcone synthase, sunscreen, gene expression.