二氧化硫对地衣中共生藻菌营养关系影响研究

为探讨地衣对大气污染特别敏感的原因 ,分离淡腹黄梅衣 (Xanthoparmelliamexicana)的共生藻和共生真菌 ,并重新合成地衣 .研究了地衣及纯化培养的藻和菌在SO2 污染短期胁迫下的生理反应 .结果表明 ,叶绿素a比叶绿素b易受伤害 ;叶绿素对 0 .5mg·L-1的熏气最敏感 ,水溶液暴露时叶绿素PQa值的下降与SO2 的吸收量有相关性 .地衣中酸性磷酸酶活性主要由共生藻所决定 .丙二醇含量在共生藻和菌以及地衣样品中无显著差异 ;还原型谷胱甘肽GSH含量在共生菌中明显高于共生藻 ,并与SO2 胁迫强度密切相关 .可以作为地衣过氧化状态和受损的生物标志物 .共生真菌承担了地衣主要的抗氧化任务 ,由于物质与能量的消耗 ,共生藻比共生菌更容易受到伤害 .

Effects of sulphur dioxide on the relationship between symbionts in lichen.

Xanthoparmellia mexicana was successfully isolating and culturing from its two symbionts and, preliminarily re-symbiosising its thalli in vitro performed from pure cultured photobiont and mycobiont. The solution exposure method was applied, confirming the toxic effect of sulfite solution with pH 4.0. The biochemical responses of lichen thalli and cultured symbionts to the short time stress of SO2 were studied. The chlorophyll PQa value of photobiont was correlated with its absorption of SO2. Chlorophyll a was more sensitive than chlorophyll b; chlorophyll was damaged most severely by the exposure of 0.5 mg.L-1 of SO2 fumigation, but was aggravated with the increase in the concentration of SO2 by way of solution exposure. The activity of acid phosphatase in lichen was mainly dependent on the photobiont. Reduced glutathione(GSH) was activated by oxidative stress of SO2. GSH was confirmed to be highly correlated with SO2 stress, and was proposed to be a significant and prospective biomarker of the status of lichen antioxidant system and the oxidative damage in lichen. The mycobiont was proposed to mainly resist the oxidative stress by SO2, while the photobiont was damaged more easily with energy depletion.