镉对紫茉莉叶片蛋白质·脯氨酸和抗氧化酶活性的影响

Effects of Cadmium on Protein,Proline and Antioxidant Enzymes Activities in Leaves of Mirabilis jalapa L.

[目的]了解镉诱导的植物生理生化变化。[方法]采用盆栽试验,以氯化镉配制土壤镉含量分别为1、5、10、25、50、100 mg/kg干土,以不加镉处理作为对照,研究镉处理20 d对80 d龄紫茉莉叶片叶绿素、蛋白质、脯氨酸含量和抗氧化酶活性的影响。[结果]随着镉处理浓度的增加,紫茉莉叶片总叶绿素和蛋白质含量、硝酸还原酶活性降低,叶绿素a/b值和脯氨酸含量升高。过氧化物酶活性随着镉处理浓度的增加而增加,可作为指示重金属植物毒性的一种生物指标。在较低浓度镉处理下,抗氧化酶活性随镉处理浓度的增加而增加,谷胱甘肽还原酶和过氧化氢酶在25 mg/kg镉处理下活性最高,而超氧化物歧化酶和抗坏血酸过氧化物酶在50 mg/kg镉处理下活性最大,但在100 mg/kg镉处理下,这4种酶的活性都明显回落,过氧化氢酶活性甚至低于对照。[结论]抗氧化酶是紫茉莉抗氧化防御系统的重要组成部分,能有效降低氧化胁迫对植株造成的伤害。

[ Objective ] The aim was to know about cadmium （Cd） induced physiological and biochemical changes in plants. [ Method ] In the pot experiment, Cd in the form of CdCl2 was added to the soil for a series of soil Cd levels of 1, 5, 10, 25, 50 and 100 mg/kg soil （ dry weight）, and treatment without adding Cd was regarded as control. The extent of damage to chlorophyll, protein, prollne, nitrate reduetase （NR）, antioxidant enzyme activity in leaves of 80-day-old Mirabilis jalapa plants were evaluated after 20 d of Cd treatment. [ Result] The contents of total chlorophyll and protein and NR activity decreased with the increase of Cd concentration, while the ratio of chlorophyll a/b and proline content increased. Peroxidase （POD） activity enhanced with the increase of Cd concentration, which was suggested as a biomarker for metal toxicity in plants. The activities of antioxidant enzymes in plants treated with lower Cd concentration enhanced with the increase in Cd concentration, and the maximal activity was recorded in plants treated with 25 mg/kg Cd for glutathione reductase （GR） and eatalase （ CAT）, and 50 mg/kg Cd for superoxicle dismutase （SOD） and aseorbate peroxidase （APX）. The activities of the above-mentioned four enzymes in plants treated with 100 mg/kg Cd were clown-regulated, especially CAT activity was even lower than control. [ Conclusion ] The activity of antioxiclant enzymes could serve as important components of antioxidant defence mechanism against oxidative injury.