铜胁迫对不同鸭跖草抗氧化系统和矿质营养代谢的影响

Effects of Copper Stress on Antioxidant System and Mineral Nutrient Metabolism of Different Commelina communis Varieties

以鸭跖草和紫鸭跖草为生物材料,采用水培法研究不同Cu2+浓度(0,25,50,75,100,125mg·L^(-1))对两种鸭跖草叶绿素含量、抗氧化酶活性、矿质营养代谢的影响。结果表明,随铜胁迫处理浓度的增大,鸭跖草SOD活性变化不大,CAT活性呈下降趋势,而POD活性、MDA含量均有增加;紫鸭跖草SOD、POD活性呈先升后降的趋势,CAT活性、MDA含量均呈下降趋势。铜浓度为125mg·L^(-1)时,鸭跖草、紫鸭跖草CAT活性最低,分别为54.6、19.4OD_(240)·(g·min)^(-1)。两种鸭跖草对溶液中铜存在主动吸收,使其叶和茎中铜积累量明显增加,锌的积累量变化不大,铁、钾积累量均呈先增后降的趋势,而紫鸭跖草镁的积累量随着溶液中铜浓度增加而降低,导致其光合作用被抑制。通过比较分析发现,两种鸭跖草茎中铜的积累量相差不大,但茎中铜的平均积累量是叶的2~10倍,茎是两种鸭跖草对铜吸收和富集的主要部位,鸭跖草、紫鸭跖草茎和叶对铜的富集系数分别为154、14.8、158.8、32.4。铜胁迫下两种鸭跖草毒害反应不同,鸭跖草较紫鸭跖草具有更强的抗氧化胁迫能力,紫鸭跖草叶中铜的积累量是鸭跖草的1.12~10.12倍。

In this study, the effects of different Cu;concentrations(0, 25, 50, 75, 100 and 125 mg·L^(-1)) on chlorophyll content, antioxidant enzyme activities and mineral nutrition metabolism of Commelina communis and Commelina purpurea were studied by hydroponic method. The results showed that SOD activity did not change and CAT activity decreased with the increase of copper stress concentration, while POD activity and MDA content increased. The activities of SOD and POD of C. purpurea increased first and then decreased, while the activities of CAT and MDA decreased. CAT activity of C. communis and C. purpurea was the lowest while copper concentration was 125 mg·L^(-1), with the scores of 54.6 OD_(240)·(g·min);and 19.4 OD_(240)·(g·min);respectively. The copper accumulation in the leaves and stems of the two plants increased obviously due to the active absorption of copper in the solution, while the zinc accumulation showed little change. And, the iron and potassium accumulation showed a trend of increasing first and then decreasing. In addition, the accumulation of magnesium in C. purpurea decreased with the increase of copper concentration in the solution, which resulted in the inhibition of photosynthesis. The results showed that there was little difference in the copper accumulation in the stems of the two plants, but the average copper accumulation in the stems was 2-10 folds higher than that in the leaves. The stems were the main parts of copper absorption and enrichment in the two plants, and the copper enrichment coefficients in the stems and leaves of the two plants were 154, 14.8, 158.8 and 32.4, respectively. The toxic responses of the two plants were different under copper stress, and C. communis showed stronger antioxidant ability than that of C. purpurea. The copper accumulation in the C. purpurea leaves was 1.12-10.12 folds higher than that of C. communis.