珙桐幼苗生理生化指标对重金属铅、镉胁迫的响应

Effects of lead and cadmium on physiology and biochemical indexes of Davidia involucrata seedlings

关键词:  珙桐, 铅, 镉, 抗氧化酶, 膜脂过氧化

Key words:  Davidia involucrata, Pb, Cd, antioxidant enzymes, membrane lipid peroxidation

摘要:

铅和镉在土壤中表现出很强的毒性,严重危害植物的生长发育。该研究着眼于中国特有濒危珍稀植物珙桐,探究盆栽实验条件下其抗氧化酶活性、丙二醛(MDA)以及游离脯氨酸、可溶性蛋白对不同浓度重金属铅、镉胁迫的响应规律。结果表明:(1)不同浓度铅处理下,珙桐幼苗MDA浓度均显著高于对照组,而镉胁迫条件下除10 mg·kg^-1浓度外,其余处理组MDA浓度也显著高于对照组,表明了铅和镉污染加剧了珙桐膜脂过氧化进程。(2)游离脯氨酸随着铅、镉浓度的增加,表现出先增加后降低的现象,分别在铅浓度≥800 mg·kg^-1和镉浓度≥20 mg·kg^-1处理下显著低于对照组。可溶性蛋白浓度随着铅浓度的增加也表现出先增后减的规律,其浓度在镉胁迫下均显著高于对照组。可溶性蛋白和游离脯氨酸的增加可以提高珙桐抵抗低浓度重金属危害的能力,高浓度重金属对珙桐则产生抑制作用。(3)随着铅和镉浓度的增加,珙桐抗氧化酶活性也表现出先增加后降低的特征,表明了低浓度重金属(铅浓度≤600 mg·kg^-1,镉浓度≤5 mg·kg^-1)容易激活珙桐抗氧化应激反应,有效地减少重金属的危害,高浓度的重金属则会抑制抗氧化酶活性。(4)通过相关性和主成分分析表明,珙桐幼苗中抗氧化酶、游离脯氨酸可以较好地反映珙桐对两种重金属胁迫的响应规律。

Abstract:

Lead(Pb)and cadmium(Cd), which are very toxic heavy metals found in soil, severely impair plant growth. This study focuses on Davidia involucrata, a rare relic plant in China, exploring the responses of the antioxidant enzymes, malondialdehyde(MDA)and free proline, soluble protein to different concentrations Pb and Cd by pot experiment. The results were as follows:(1)The concentrations of MDA in D. involucrata seedlings were higher in different concentrations of Pb than that in the control group. The MDA concentrations of the different concentrations of Cd, except for the concentration was 10 mg·kg^-1, was significantly higher than that in the control group, indicating the increased degree of cell membrane lipid peroxidation of D. involucrata.(2)Free proline concentration of osmoregulation substances initially increased and then decreased with the increase concentrations of Pb and Cd, which was lower than that in the control group under treatment of Pb concentration ≥800 mg·kg^-1 and Cd concentration ≥20 mg·kg^-1, respectively. With the increase of Pb concentration, the soluble protein concentration also showed an initial increase and then decrease trend. The concentrations of soluble protein were higher in the treatment groups of Cd than that in the control group. The increase of soluble protein and free proline enhanced the stress resistance of D. involucrata to resist the damage. In addition, the high concentration of heavy metals inhibited the growth of D. involucrata.(3)Antioxidant enzyme activities also initially increased and then decreased with the increase of Pb and Cd concentrations, indicating that low concentrations of heavy metals(Pb concentration≤600 mg·kg^-1 and Cd concentration≤5 mg·kg^-1)could easily activate the antioxidant capacity of D. involucrata and it could deal with the harm, while high concentrations of heavy metals could inhibit the activities of antioxidant enzymes.(4)The correlation and principal component analysis showed that antioxidant enzymes and free proline in D. involucrata seedlings had important indicative effects on the stresses of the two heavy metals.