Physiological defence mechanism of Ligularia intermedia against UV-B radiation on Dongling Mountain

Ligularia intermedia growing at different altitudes were used to investigate the mechanism of ultraviolet (UV) resistance on physiological aspects in the field. The tests compared the absorbance of the UV absorbing compound, the content of chlorophyll a, chlorophyll b, and carotenoids, and the activities of peroxidase (POX) and superoxide dismutase (SOD) in Ligularia intermedia growing at three different altitudes on Dongling Mountain in northern China. There were no significant differences between the plants growing at 1160 m and 1820 m. However, all of these factors increased dramatically at 2190 m. The results indicate that the UV resistance of the plants mainly depends on the mechanism of filtering the radiation and preventing the reactive oxygen species (ROS) damage produced by UV B