硫对镉胁迫下小白菜叶片AsA-GSH循环和植物络合素含量的影响  

Effects of Sulfur on Ascorbate-Glutathione Cycle and the Content of Phytochelatins in the Leaves of Pakchoi (Brassica chinensis L.)Under Cadmium Stress

作　　者：孙惠莉[1] 吕金印[2] 贾少磊[1] 

机构地区：[1]西北农林科技大学理学院,陕西杨凌712100 [2]西北农林科技大学生命科学学院,陕西杨凌712100

出　　处：《农业环境科学学报》2013年第7期1294-1301,共8页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(31271624)

摘　　要：采用水培试验研究了不同镉、硫水平对小白菜叶片中抗坏血酸-谷胱甘肽(AsA-GSH)循环和植物络合素含量的影响。结果表明,适度增硫降低了镉胁迫下小白菜叶片中过氧化氢(H2O2)和丙二醛(MDA)含量,提高了AsA-GSH循环中关键酶的活性、抗氧化物质和植物络合素的含量。低镉(5μmol·L-1)水平下,随着硫浓度的增加,小白菜叶片中H2O2的含量显著下降,MDA含量先降后升,谷胱甘肽还原酶(GR)活性、抗氧化物质及植物络合素含量持续升高,抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDHAR)及AsA含量呈先升后降的趋势,且均在3mmol·L-1硫处理达到峰值。高镉(50μmol·L-1)水平下,随着硫浓度的增加,小白菜叶片中H2O2和MDA含量均先降后升,AsA-GSH循环关键酶活性、抗氧化物质及植物络合素含量均呈先升后降趋势,且多数在2mmol·L-1硫处理达到峰值。研究表明适度增硫处理能维持小白菜叶片AsA-GSH循环快速有效地运转,增加植物络合素的合成,保持较强的抗氧化物质的再生能力和重金属螯合解毒能力,对降低镉胁迫伤害具有重要作用。但是过高SO2-4离子浓度存在一定的盐胁迫毒害效应,因而影响其对小白菜镉生物毒性的降低作用。A series of hydroponics experiments were performed to investigate effects of sulfur on ascorbate（AsA）-glutathione（GSH） cycle and the content of phytochelatins（PCs） in pakchoi（Brassica chinensis L.） leaves under cadmium（Cd） stress. The results showed that application of moderate level of sulfur decreased the contents of peroxide（H2O2） and malondialdehyde（MDA）, but increased key enzyme activities and antioxidant content of AsA-GSH cycle in pakchoi leaves. Under low Cd stress（5 μmol·L^-1, the content of H2O2 were significantly decreased and the content of MDA fell first then rose with increasing concentration of sulfur, while PCs content and the activity of glutathione reductase（GR） were raised. Along with the increase of the sulfur concentration, other key enzymes activities, such as ascorbate peroxidase（APX）, dehydroascorbate reductase（DHAR） and monodehydroascorbate reductase（MDHAR） in AsA-GSH cycle and the content of AsA increased at the beginning, reaching to the peak in the 3 mmol·L^-1 sulfur level. Under high Cd stress（50 μmol·L^-1, the contents of H2O2 and MDA decreased first then increased, while the key enzymes activities and antioxidant content of AsA-GSH cycle showed an opposite tendency, and many of them reached to the peak in the 2 mmol·L^-1 sulfur level. The results indicated that application of moderate level of sulfur could maintain the efficiency metabolism of AsA-GSH cycle during the stress period, increase the synthesis of PCs and keep the regenerative capacity of antioxidant substances and heavy metal chelating ability. Although sulfur plays an important role in reducing Cd toxicity, overhigh concentration of SO2-4 could cause toxicity of salt stress and thus affect its Cd toxicity relief.

关 键 词：小白菜 镉 硫 抗坏血酸 谷胱甘肽 植物络合素 

分 类 号：X503.231[环境科学与工程—环境工程]