镉胁迫对烟草愈伤组织抗氧化系统的影响

Effect of cadmium stress on antioxidative system in tobacco callus

镉（ca）是烟草（Nicotiana tabacumL．）生长的非必需元素，但容易在烟草体内残留，危害其生长发育。本实验设定0～50mg·L-1 7个梯度浓度的Cd2＋，以MS＋1．0mg·L-1 6-BA＋0．5mg·L-1 NAA为基本培养基，诱导产生烟草叶片愈伤组织。待45d愈伤组织丰富之后，每间隔3d测定一次烟草愈伤组织内抗氧化系统相关酶活性、活性氧水平及丙二醛含量。结果表明：短期（45～51d）Cd2＋胁迫可导致烟草愈伤组织内活性氧水平升高，抗氧化酶系统活性增强，但长期（51～57d）高浓度C2＋胁迫导致抗氧化系统活性下降，膜质过氧化程度加重。

Cadmium is a non-essential element for plant growth, however, it could be absorbed and remained easily, and make an obvious damage to tobacco （Nicotiana tabacum L. ）. In this study, tobacco leaves were induced to produce callus by the minimal medium （MS ＋ 1. 0 mg· L-1 6-BA ＋ 0.5 mg · L-1 NAA）. After 45 days, with a large amount of callus, the activi- ties of related enzymes （SOD, CAT, APX, MDAR, GR and DHAR） in the antioxidant system, the levels of reactive oxygen species （ O2, H2 02 ）, and malondialdehyde （MDA） content were measured every three days. The results showed that the reactive oxygen species enhanced, and the activities of antioxidantive enzymes increased in tobacco callus under the cadmium stress with- in 45-51 days. However, after 51-57 days the activities of antioxidantive system, and mem- brane lipid peroxidation were aggravated, indicating that the increasing activities of antioxidantive system could not resist the long-term （54-57 days） high cadmium stress.