Abstract: The seedlings of wheat were exposed to He-Ne laser(5 mW·mm^-2) irradiation and enhanced UV-B(10.08 kJ·m^-2d^-1) radiation. Then the content changes of chloroplast pigments and the composition of pigment-proteins were measured in order to test the mitigative effect of He-Ne laser irradiation on injury by enhanced UV-B radiation. After treating wheat seedlings for 4 days circularly, chloroplast pigments were extracted respectively by 90% ethanol and 80% acetone. The contents of chloroplast pigments were detected with spectrophotometer or paper chromatography. The composition of pigmentproteins were detected with column chromatography. It suggested that the content of chloroplast pigments decreased 17.76% approximately in wheat seedlings by enhanced UV-B radiation. The binding degree of Chl-Pro is weakened. The composition of pigment-proteins also differed from the control group. Straps of D1 and D2 proteins lost. However, the content of chloroplast pigments increased about 10.64% exposed to He-Ne laser irradiation, but decreased 8.12% comparing with the control. The binding degree of Chl-Pro is higher than the B group. At the same time, the composition of pigmentproteins was similar with the control group. So the lower dose of He-Ne laser irradiation can partly repair the radiation injury on chloroplast pigments and pigment-proteins in wheat seedlings after enhanced UV-B radiation.

Key words: He-Ne laser, ultraviolet-B radiation, chloroplast pigment, wheat