【摘要】 大气平流层臭氧层减薄引起到达地表的 UV- B辐射增强。为探讨在增强 UV- B辐射下植物细胞 DNA的损伤修复和蛋白质含量的关系 ,利用 3H- Td R掺入法 ,研究了在 8.2 2 k J/(m2 d)和 12 .4 2 k J/(m2 d) U V- B辐射 (相当于兰州地区大气平流层臭氧减薄约 12 %和 2 0 % )胁迫下 ,大豆胚轴细胞 DNA合成和非按期合成 (UDS)变化 ,并测定了胚轴蛋白质含量变化 ,结果显示 ,UV- B辐射导致 DNA损伤 ,并诱导了 DNA损伤的修复 ,胚轴细胞 UDS效应增强 ,U DS指数增大。低 UV- B辐射强度下 ,胚轴蛋白质含量增加 ,可能是 U V- B诱导了一些与抗性有关的基因表达 ,导致一些新的与抗性有关的蛋白质合成 ;在高强度 UV- B辐射下 ,U DS指数与低强度辐射下无显著差异 (P=0 .0 5 ) ,但蛋白含量较低强度辐射下显著下降 (P=0 .0 5 ) ,说明高强度 UV- B辐射加重了 DNA损伤 ,而修复并未加强 ,并且高强度辐射抑制基因的正常表达和蛋白质合成。这些蛋白质的合成可能与大豆对 UV- B辐射的抗性有关。更多还原

【Abstract】 Ozone depletion in the upper atmosphere cause increasing doses of UV-B on the earth’s surface and understanding how plants protect themselves against this exposure is important to maintain crop productivity. Soybean hypocotyls were treated with doses of UV-B at 8.22 kJ/(m²d) and 12.42 kJ/(m²d) UV-B radiation, corresponding to depletions in the stratospheric ozone of about 12 % and 20%, respectively, for a clear solstice day at Lanzhou city （36.04°N, 1550m）,China. DNA synthesis and unscheduled DNA synthesis was assessed by measuring the incorporation of 3H-TdR into DNA along with changes in hypocotyls protein content. Repair of induced DNA damage, unscheduled DNA synthesis and protein synthesis was increased in response to the lower dose of UV-B radiation. At higher UV-B dose, there was no significant difference （ P =0.05） in unscheduled DNA synthesis but a significant decrease （ P =0.05） in protein contents in the exposed hypocotyls. Higher UV-B irradiation could have caused DNA damage that could not be repaired because the relevant protective proteins were not synthesized. Resistance to UV-B in soybean may be highly dose dependent due to limitation in the induction of protective proteins.更多还原