增强UV-B辐射和He-Ne激光辐照对小麦离体叶绿体光化学活性的影响

利用低剂量的He-Ne激光和增强UV-B处理小麦叶绿体,研究了He-Ne激光对UV-B辐射损伤的修复效应.将提取的离体完整叶绿体分成CK(对照)、L(激光)、B(UV-B)和BL(UV-B和He-Ne激光复合处理)不同处理组.B、BL组经过不同剂量的紫外辐照处理(剂量依次为0.42 kJ·m－2·d－1,0.84 kJ·m－2·d－1 ,1.26 kJ·m－2·d－1),其中BL组被UV-B辐射处理后再用He-Ne激光(5 mW·mm－2)辐照.利用低温荧光法测定不同处理组小麦叶绿体荧光发射光谱的变化;用电导仪和Clark氧电极仪分别测量叶绿体膜透性和电子传递速率,膜透性的改变从一定程度上能反应膜的损伤程度;ATPase活性采用分光光度计测量.研究表明:He-Ne激光和增强UV-B辐射影响叶绿体激发能的分配,UV-B辐照达到1.26 kJ·m-2·d－1时,叶绿体几乎完全失去活性；He-Ne激光则从一定程度上能促进叶绿体的光化学活性.UV-B辐射后的叶绿体再经过He-Ne激光的辐照处理后,可以恢复部分光化学活性,但当叶绿体损伤严重,光化学活性完全丧失时,He-Ne激光对其没有激活作用.

Effects of He-Ne Laser and Enhanced UV-B Radiation on Photochemical Activities of Chloroplasts in Wheat (in Vivtro)

The repair effects and mechanism of He-Ne laser (5 mW·mm－2) irradiation on the intanct chloroplasts of wheat cell induced by enhanced ultraviolet-B radiation are studied. Isolated intanct chloroplasts of wheat cell are divided into CK(control ), L(He-Ne laser ), B( UV-B ) and BL(He-Ne laser+ UV-B ) four different treatments. The chloroplasts of B and BL are treated by different dose UV-B irradiation(0.42 kJ·m－2·d－1, 0.84 kJ·m－2·d－1 , 1.26 kJ·m－2·d－1), for BL, and following He-Ne laser irradiation. The results indicate that distribution of excitation energy between PSI and PSII is changed, the rate of electron transport and ATPase activity are declined, and the relative permeability of chloroplasts membrane is increased by UV-B irradiation, when the UV-B radiation dose is increased to 1.26 kJ·m－2·d－, the photochemical activities of chloroplasts is almost lost, which all can be promted by He-Ne laser irradiation before losing it′s activities completely. For BL, the damages induced by UV-B radiation are not more serious than B. The results suggest that the photosynthetic characteristic of the chloroplasts are changed and photochemical activities are lost by enhanced UV-B radiation, which can be partly repaired by He-Ne laser irradiation.