镉诱导的菊芋幼苗膜脂过氧化和抗氧化酶活性及过氧化物酶同工酶的改变

用含有不同浓度(0~400μmol/L)Cd(NO3)2的Hoagland营养液处理砂培的菊芋。处理50d后,测定植物体内镉积累量以及过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性,并对POD同工酶进行电泳分析。发现在Cd50~100μmol/L浓度内,随着镉浓度的升高,菊芋根和叶中镉的积累量显著增加,而随后积累量的增加有所减少。根和叶中MDA含量显著上升,说明镉引起了膜脂过氧化。0~100μmol/LCd处理,根和叶中POD活性随Cd浓度增加而增强,而在200~400μmol/LCd处理下有所减弱。根和叶SOD活性在50~200μmol/LCd处理下随Cd浓度增加而增强,而在400μmol/LCd处理下SOD活性明显受到抑制。根和叶CAT活性随Cd浓度升高而增强。电泳结果显示,POD同工酶变化明显,镉诱导出一条新酶带LP10。菊芋POD同工酶可以作为镉污染的土壤的生物指示剂。

Cadmium-induced Membrane Lipid Peroxidation and Changes in Antioxidant Enzyme Activities and Peroxidase Isoforms in Jerusalem Artichoke Seedlings

Jerusalem artichoke (Helianthus tuberosus L.) seedlings cultured in sandy media were treated with Hoagland nutrition solution with different concentrations of Cd(NO(3))(2) from 0 to 400 micromol/L. After 50 days' treatment, Cd accumulation, activities of peroxidase (POD, EC 1.11.1.7), superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) were measured and electrophoretograms of POD isoenzymes were analyzed. The accumulation of Cd in seedlings increased from Cd 50-100 micromol/L, after which further increases in Cd concentration resulted in only small increases in accumulation of Cd in seedlings. MDA content was markedly higher than control values indicating the enhanced membrane lipid peroxidation in roots and leaves. POD activities in leaf and root extracts increased with an increase of Cd concentration from 0 to 50 and 100 micromol/L and then decreased with further increases to 200 and 400 micromol/L. Under moderate Cd level of 50-200 micromol/L, SOD activities in leaf and root extracts increased whereas with a higher Cd level of 400 micromol/L marked inhibitions in enzyme activities were observed. With increase in Cd concentration marked elevations in CAT activities in leaves and roots were observed. Results of electrophoresis show that the alteration of POD isoenzyme was noticeable to Cd and an additional POD isoenzyme LP10 appeared. It is suggested that POD isoenzyme of Jerusalem artichoke seedlings could be used as bioindicator for soil contamination by Cd.