低剂量^(60)Co-γ辐射种子预处理对黑麦草紫外线B辐射伤害的保护作用

Effect of Seed Pre-treatment by Low-dose Gamma-ray Radiation on Reduction of Ultraviolet-B Caused Injury in Ryegrass Seedlings

将经过低剂量60Co-γ辐射(0、5、10、20和30 Gy)种子预处理的黑麦草(Lolium perenne L.,品种‘Victorian’)幼苗在室内控制条件下进行紫外线B辐射[6.5 kJ/(m2.d)]处理。UV-B辐射导致严重的苗体伤害,比如衰老加快、生长抑制和膜脂过氧化,然而低剂量的60Co-γ辐射(LDG)种子预处理显著降低了苗体UV-B伤害,尤其是20和30 Gy(1 Gy=1 J/kg)。抗坏血酸和UV吸收化合物在LDG处理下显著升高,UV化合物进一步被UV-B辐射提高了2倍以上;30 Gy处理的叶片光合色素一直维持在较高的水平。因此我们推测植株UV-B耐性在LDG处理下的提高至少部分归咎于抗坏血酸和UV化合物含量的提高,以及保持高水平光合色素的能力。本研究还探讨了LDG和UV-B复合处理的耐性机制。

Ryegrass （ Lolium perenne L. , cv.‘ Victorian＇ ） seedlings from seed pretreated with low-dose gamma irradiation （LDG） were exposed to 6.5 kJ/（ m^2· d） UV-B radiation under controlled environmental conditions. The high level of UV-B radiation caused serious plant injury, such as acceleration of senescence, growth inhibition and lipid oxidation of cell membrane, but the UV-B induced injury was alleviated significantly by LDG-pretreatment, in particularly by 20 and 30 Gy （ 1 Gy = 1 J/kg）. Both ascorbic acid （AA） and UV-absorbing compounds were increased by LDG-pretreatment, and the later were further enhanced by UV-B irradiation. Under UV-B exposure the levels of photosynthetic pigments remained high in the seedling with seed-pretreatment by 30 Gy. We suggest that increased plant tolerance to UV-B damage caused by LDG pretreatment may be due in part to higher contents of ascorbic acid and UV-absorbing compounds, and the ability to maintain high levels of photosynthetic pigments. The possible implications of these observations are discussed.