NaCI胁迫对UV-B辐射诱导的绿豆环丁烷嘧啶二聚体和紫外吸收物质含量变化的影响

将2个对UV-B敏感性不同的绿豆品种‘秦豆-20’和‘中绿-1’幼苗放在培养室内,进行0.4W/m~2 UV-B辐射和0.4%NaCl胁迫的单独或复合处理,研究了NaCl胁迫对UV-B辐射诱导的DNA伤害和修复的影响。结果显示:在NaCl胁迫下,(1)在光下抗UV-B的品种‘中绿-1’的环丁烷嘧啶二聚体(CPD)累积量降低,而敏感品种‘秦豆-20’的CPD累积量未发生变化;(2)两品种CPD形成量均比无NaCl胁迫时低;(3)抗UV-B品种DNA的光、暗修复能力均比无NaCl胁迫时高:(4)而敏感品种DNA的光修复能力比无NaCl胁迫时低、暗修复能力未发生变化。另外,CPD形成量与紫外吸收物含量间具有明显的负相关性。说明NaCl胁迫不仅影响2个绿豆品种幼苗的CPD形成量,而且影响DNA的光、暗修复能力,进而导致了CPD累积量发生变化,由此影响了幼苗的UV-B敏感性。结果也暗示CPD形成量的变化是由于紫外吸收物质含量的不同所导致的。

Effects of NaCI Stress on Changes in the Ultraviolet-B Radiation-induced Cyclobutyl Pyrimidine Dimer and Ultraviolet Absorbing Compound Contents in Mung Bean

In two mung bean cultivars (Phaseolus raditus L. cv. 'Qindou-20' and 'Zhonglv-1') with different sensitivities to UV-B grown in growth chamber under supplemental or no supplemental UV-B radiation (0.4 W/m(2)) with or without 0.4% NaCl, the effects of NaCl stress on UV-B-induced DNA damage and repair were studied. The results showed that, under NaCl stress, (i) CPD accumulation was lower in the tolerant cultivar 'Zhonglv-1' but was the same in the sensitive cultivar 'Qindou-20', (ii) CPD formation in both cultivars was weakened, (iii) the photorepair and dark repair capacity were higher in the tolerant cultivar and (iv) the photorepair was weakened and dark repair capacity did not change in the sensitive cultivar. There was a negative correlation between susceptibility of CPD formation and levels of UV-absorbing compounds. These results demonstrate that NaCl stress can affect not only the susceptibility to CPD formation, but also the capacities for photorepair and dark repair of DNA, which together result in the change in UV-B-induced CPD accumulation and thereby that in sensitivity of plant to UV-B. The results also suggest that the differences in susceptibilities to CPD formation are due to the differences in levels of UV-absorbing compounds.