皇竹草活性氧代谢对阿特拉津胁迫的响应特征

采用水培实验研究了4个浓度（5、10、20、40 mg·L^-1）除草剂阿特拉津胁迫下,皇竹草（Pennisetum hydridum）叶片内超氧阴离子生成速率、过氧化氢（H₂O₂）含量、超氧化物歧化酶（SOD）活性、过氧化氢酶（CAT）活性、过氧化物酶（POD）活性、丙二醛（MDA）含量、原生质膜透性的变化,探讨皇竹草对阿特拉津的抗性及其生理机制。结果显示:（1）低浓度（5、10 mg·L^-1）的阿特拉津胁迫使皇竹草叶片内超氧阴离子生成速率和CAT活性升高,却使H₂O₂含量及SOD和POD活性降低,但随着培养时间的延长,培养液中阿特拉津浓度的降低导致上述指标又有恢复到正常水平的趋势;而高浓度（40 mg·L^-1）的阿特拉津胁迫则使皇竹草叶片内H₂O₂含量、SOD、POD和CAT活性持续降低。（2）在各胁迫浓度下持续胁迫10 d后,皇竹草叶片内MDA含量开始逐渐升高,并且升高幅度随着胁迫浓度的提高而明显增加,但各胁迫浓度下叶片原生质膜相对透性未见明显的变化。研究表明,皇竹草可能通过活性氧等信号分子调控自身保护酶系统的活性来缓解阿特拉津造成的伤害,从而对低浓度（5、10 mg·L^-1）的阿特拉津胁迫表现出较强抗性。

Response Characteristics of Reactive Oxygen Metabolism in Pennisetum hydridum to Atrazine Stress

Hydroponics experiments were conducted to study the effects of atrazine stress (5,10,20,40 mg·L^-1) on O^-·₂ production rate,H₂O₂ content,activities of superoxide dismutase (SOD),catalase (CAT) and peroxidase (POD),malondialdehyde (MDA) content and plasma membrane permeability in leaves of Pennisetum hydridum,and the resistance and physiological mechanisms of P.hydridum to atrazine stress were discussed.The results indicated,plant samples were collected after 5,10,15 and 20 days.(1)Low level of atrazine stress (5,10 mg·L^-1) elevated O^-·₂ production rate and CAT activity in leaves of P.hydridum,and decreased H₂O₂ content,the activities of SOD and POD.With prolonging of cultivation time,the above indexes have returned to normal levels,but high level of atrazine stress (40 mg·L^-1) decreased H₂O₂ content,the activities of SOD,CAT and POD in leaves of P.hydridum continuously.(2)After 10 days,MDA content in leaves of P.hydridum treated by all levels of atrazine stress began to increasing.With the increase of atrazine concentration,the increasing amplitude of MDA content was significantly increased.All levels of atrazine stress showed no significant effects on relative permeability of plasma membrane.Therefore,P.hydridum probably regulates the activities of protective enzymes by signaling molecules such as reactive oxygen species,which could alleviate the injury caused by atrazine,and thus P.hydridum showed strong resistance to low level of atrazine stress (5,10 mg·L^-1).