玉米叶片涝渍伤害过程中超氧自由基的积累

ACCUMULATION OF SUPEROXIDE RADICAL IN CORN LEAVES DURING WATERLOGGING

土壤淹水后玉米（Ｚｅａ ｍ ａｙｓ Ｌ．）叶片中超氧阴离子自由基（Ｏ·２ ）的产生速率以及过氧化氢（Ｈ２Ｏ２）含量都显著增加，Ｏ·２ 的增幅大于Ｈ２Ｏ２，Ｏ·２ 产生速率与丙二醛（ＭＤＡ）积累、电解质泄漏以及叶绿素降解都呈显著正相关。涝渍胁迫削弱了活性氧清除系统，其中ＳＯＤ活性的下降位于抗坏血酸过氧化物酶（ＡＰ）活性以及抗坏血酸（ＡｓＡ）和谷胱甘肽（ＧＳＨ）含量下降之前。向受涝植株喷施Ｏ·２ 产生剂百草枯（ＰＱ），导致Ｏ·２ 产生速率、Ｈ２Ｏ２和ＭＤＡ 含量的迅速增高。ＳＯＤ的抑制剂ＤＤＴＣ能明显提高受涝叶片的Ｏ·２ 水平。结果表明，玉米叶片的涝渍伤害可能是由于ＳＯＤ 活性被抑制，导致Ｏ·２

The changes in superoxide (O 2) production, hydrogen peroxide (H 2O 2) content and active oxygen scavenging system in corn (Zea mays L.) leaves under waterlogging stress were investigated to explore the relationship between O 2 accumulation and waterlogging injury. Corn plants were grown in pots in a controlled environment. The results showed that prolonged waterlogging treatment conducted at 4 leaf stage caused a significant increase in the production of O 2 and H 2O 2, while the extent of O 2 change was more than that of H 2O 2. Malondialdehyde (MDA) accumulation, chlorophyll loss and electrolye leakage were positively correlated with O 2 production in corn waterlogged leaves. Foliage spraying with 0 1 mmol/L paraquat (O 2 producer) at the start of waterlogging treatment led to a significant increase in O 2, H 2O 2 and MDA levels. The addition of DDTC (SOD activity inhibitor) aggravated O 2 formation in waterlogged leaves. Waterlogging apperantly reduced the activities of SOD, catalase (CAT), ascorbate peroxidase (AP) and the concentrations of ascorbic acid (AsA) and glutathione (GSH). It was noted that the decline in SOD activity proceeded the diminishment of H 2O 2 scavengers in chloroplasts (i. e. AP, AsA and GSH). The present findings suggest that O 2 is involved in waterlogging damage, and excessive accumulation of O 2 is due to the reduced SOD activity.