外源水杨酸对锰污染红壤中玉米的生长与抗氧化酶活性的调节作用

采用盆栽实验方法研究了外源水杨酸（SA）对锰污染红壤中玉米的生长、脂质过氧化程度、活性氧水平以及抗氧化酶活性的影响。结果表明,过量锰明显降低玉米植株干重,显著提高了茎叶和根中锰的含量。SA促进锰胁迫下玉米的生长,但对植株中锰的含量与分布无影响。过量锰处理下,玉米叶片超氧阴离子（O.2-）和过氧化氢积累显著增加,脂质过氧化、电解质渗透率和脯氨酸含量显著升高;而SA和过量锰复合处理下,这些指标则显著降低。过量锰诱导超氧化物歧化酶（SOD,EC1.15.1.1）、过氧化物酶（POD,EC1.11.1.7）活性升高,抑制过氧化氢酶（CAT,EC1.11.1.6）和抗坏血酸过氧化物酶（APX,1.11.1.11）活性;SA处理促进锰胁迫下SOD和POD活性进一步升高,减小CAT和APX活性下降的程度。这些结果提示,SA调节抗氧化酶活性,保护组织细胞免遭氧化损伤,是SA缓解过量锰对玉米毒害作用的重要生理原因。

Modulation of Growth and Antioxidative Enzyme Activities of Zea mays L. in Manganese-contaminated Red Soil by Exogenous Salicylic Acid

Pot experiment was employed to investigate the effects of salicylic acid（ SA ）on the growth, lipid peroxidation, electrolyte leakage rate, reactive oxygen species（ROS）accumulation and antioxidative enzyme activities of maize plants（Zea mays L. ）in a red soil contaminated with excess manganese （Mn）. The results indicated that excess Mn dramatically reduced the dry weight of maize plants, and significantly increased the Mn content in both shoots and roots. Treatment with SA promoted the growth of maize plants under Mn stress, demonstrating alleviating effects of Mn toxicity in maize plants by SA treatment, but had no obvious effects on the distribution and content of Mn in plants. The accumulation of superoxide anion and H202, proline production, lipid peroxidation and electrolyte leakage significantly increased in maize leaves exposed to excess Mn, whereas the values of these parameters were much lower in the plants treated with SA and excess Mn. Treatment with excess Mn enhanced the activities of superoxide dismutase （SOD, EC 1.15. l. 1 ）and guaiacol peroxidase （POD, EC 1.11.1.7 ）, while inhibited the ones of catalase （CAT, EC 1.11.1.6）and ascorbate peroxidase （APX, EC 1.11.1.11 ）. However, SA application increased further the activities of SOD and POD, and diminished the decrease in the activities of CAT and APX in the plants exposed to excess Mn. It is con- cluded that SA modulates the activities of antioxidative enzymes to protect maize plants from oxidative damages may be an important physio- logical reason for SA-induced alleviation of Mn toxicity.