模拟酸雨对水稻叶片质膜H^+-ATPase与质膜过氧化的影响

Influence of simulated acid rain on the plasma membrane H^+-ATPase and peroxidation of plasma membrane in rice leaves

在水培条件下研究酸雨(pH值为2.5~5.5)对水稻叶片质膜过氧化与H+-ATPase活性的影响。结果表明,与对照相比,pH≥3.5酸雨处理下的水稻叶片质膜H+-ATPase活性、质膜透性、丙二醛(MDA)含量、过氧化氢(H2O2)含量和过氧化氢酶(CAT)活性(pH=3.5下CAT活性除外)无显著变化(p<0.05);pH≤3.0处理组质膜H+-ATPase活性随酸雨pH值降低呈先升后降趋势,其余指标随pH值降低而增大,表明质膜H+-ATPase活性受抑使质膜过氧化加剧。在恢复期,pH≥3.5处理组各指标仍无显著变化(p<0.05);pH=3.0组各指标变幅减小,H+-ATPase与CAT活性恢复至CK(对照),表明植物自修复使质膜过氧化减轻;pH=2.5组H+-ATPase活性仍低于CK,质膜透性和MDA含量不仅高于CK且高于胁迫期,表明质膜H+-ATPase活性受抑使质膜过氧化持续。在高强度酸雨(pH≤3.0)的胁迫下,水稻叶片质膜H+-ATPase活性的变化与质膜过氧化程度密切相关。

The present paper is aimed at investigating the influence of simulated acid rain on the plasma membrane H＋ - ATPase and per oxidation of plasma membrane in the rice leaves, particularly in the rice seedlings under the greenhouse condition. In our investigation, we have divided the rice seedlings into six groups to be treated with simulated acid rain at different pH values （2.5, 3.0, 3.5, 4.0, 5.0 and 5.5）, but for one group to be treated with neutral solution （pH 7.0） as the control group. The results of our investigation indicate that H ＋ - ATPase activity of the plasma membrane, the cytoplasm membrane permeability, MDA contents, H202 contents and CAT ac tivity turned to have no obvious difference from those of the control group （p 〈 0.05） when the pH value of acid rain was kept under no lower than 3.5, except when the CAT activity was higher than that of the control at pH 3.5. However, when the pH value of acid rain was not beyond 3.0, all the indexes would decrease with the decrease of the pH value of the acid rain except that H ＋ - ATPase activity first increased and then decreased. The above results indicate that the de- crease of H ＋ - ATPase activity tends to intensify the degree of perox idation of plasma membrane. During the recovery period, if the pH value of acid rain remained not lower than 3.5, all the indexes would make no obvious difference from those of the control group （p 〈 0.05）. However, at pH 3.0, the range of variation of all indexes would begin to decrease, with H＋ - ATPase activity and CAT activity were returning to the level of the control group. The results mentioned above prove that the ability of the seedlings for restoration could alle- viate the peroxidation of the plasma membrane. When pH value of the acid rain was 2.5, the H ＋ - ATPase activity would still be kept low er than that of the control. However, the membrane permeability and MDA contents turned to be higher than those of the control, even higher than those measured during the stress period. The said result may account for the continuation of the peroxidation of plasma mem- brane on the condition that the H ＋ - ATPase activity was inhibited. By making a comparison between the results measured during the stress period and the recovery period, it can be found that the changes in H ＋ - ATPase activities may account for their relation with the degree of peroxidation of plasma membrane treated with low pH acid rain （pH〈3.0）.