Abstract: In order to elucidate the effects of 0.05,0.1 and 1.0 mg·L^-1 selenium (Se) on plant height,root length,electrolyte leakage (EL),malondialdehyde (MDA) content,antioxidant enzyme activity and gene expression level of ryegrass under Cd stress,annual ryegrass ‘Jiewei’ were used to treated with 60 mg·L^-1 cadmium (Cd) in growth chambers. The results showed that plant height and root length decreased and EL and MDA content increased under Cd stress;The activity of superoxide dismutase (SOD) increased while activity of peroxidase (POD)was decreased;The gene expression level of glutathione reductase (GR),glutathione peroxidase (GPX) and manganese superoxide dismutase (MnSOD) were decreased and peroxisomal ascorbic peroxidase (pAPX) and catalase (CAT) were increased under Cd stress. The damages caused by Cd stress were alleviated by the addition of Se,demonstrated by the increase of plant height,root length and POD activity,and decreased EL,MDA content and SOD activity. The results suggest that appropriate Se concentration could regulate the antioxidant defense system that contribute to the enhanced Cd tolerance,which 0.1 mg·L^-1 Se is the best concentration.

Key words: Selenium, Cadmium stresses, Ryegrass, Growth and physiology, Antioxidant enzyme

摘要： 为明确外源硒对重金属镉胁迫下黑麦草（Lolium multiflorum）的影响，本研究以一年生黑麦草品种"杰威"（Lolium multiflorum ‘Jiewei’）为试验材料，分析了施加0.05、0.1和1.0 mg·L^-1硒对镉胁迫（60 mg·L^-1）下黑麦草株高、根长、电导率（Electrolyte leakage，EL）、丙二醛（Malondialdehyde，MDA）含量、抗氧化酶活性及其基因表达的影响。结果表明：60 mg·L^-1镉胁迫下黑麦草株高和根长显著（P<0.05）降低，EL和MDA含量显著升高，同时超氧化物歧化酶（Superoxide dismutase，SOD）活性显著升高而过氧化物酶（Peroxidase，POD）活性显著降低，谷胱甘肽还原酶（Glutathione reductase，GR）、谷胱甘肽过氧化物酶（Glutathione peroxidase，GPX）、锰超氧化物歧化酶（Manganese superoxide dismutase，MnSOD）基因表达量显著下调，而过氧化物体抗坏血酸过氧化物酶（Peroxisomal ascorbate peroxidase，pAPX）和过氧化氢酶（Catalase，CAT）基因表达量则显著上升；施加外源硒后，镉胁迫得到缓解，在硒浓度为0.1 mg·L^-1时，株高和根长缓解效果最明显，EL和MDA降低，SOD活性下降以及POD活性上升，抗氧化酶基因表达量也恢复至对照水平，表明施加适宜浓度外源硒可调节抗氧化能力，从而维持细胞膜稳定性和有效缓解镉胁迫对黑麦草的毒害现象，其中硒浓度为0.1 mg·L^-1时效果最好。

关键词: 硒, 镉胁迫, 黑麦草, 生长和生理, 抗氧化酶