盐胁迫对棉花幼苗子叶超氧化物歧化酶(SOD)活性的影响

The Effect of Salt Stress on Superoxide Dismutase in Cotton Seeding Cotyledon

棉花幼苗子叶 SOD 活性在细胞内的分布是细胞溶质部分活性最高。其次是线粒体,再次是叶绿体。各细胞器 SOD 活性对盐分的敏感程度不同,依次是叶绿体>线粒体>细胞溶质部分。在盐分胁迫初期,棉花幼苗子叶能够维持较高 SOD 活性,但随着盐胁迫强度的增加,棉花幼苗子叶 SOD 活性下降和膜透性增加,幼苗表现出盐害症状,SOD 活性下降比膜透性增加出现的早。轻度盐分胁迫随时间延长,鲁棉6号的子叶 SOD 活性有一定增加,表明棉花幼苗具有一定的耐盐能力。耐盐性不同的两个品种在 SOD 活性和细胞质膜透性变化上有差异,并对 SOD 作为棉花抗盐碱育种指标进行讨论。

The localization of superoxide dismutase(sod),changes in membrance perme- ability and SOD activity were characterized in various organelles of cotyledon of cotton seedling with different salt tolerance during salt stresses.The localization of SOD activity in various or- ganelles of cotton seedling cotyledon is that:cell solute has the highest activity,then is the mi- tochondria and chloroplast.The sensitivities of SOD to salt stresses in various organelles are different,with the highest being in chloroplast,then in mitochondria and in cell solute.The higher SOD activity could be maintained in cotton seedling cotyledon at primary stage of salt stress.Under serere salt stress condition,SOD activity declined and membrane pereability raised,then the salt injury symptoms gradually appeared in cotton leaves.However,a signifi- cant reduction of SOD activity appeared before the membrane permeability.Moreover,SOD activity significantly raised at the late stage under appropriate salt condition.This shows cotton seedling have a certain ability to salt tolerance.The seedling of two cotton cultivars with def- ferent salt tolerance exhibited some differences in both SOD activity and membrane pereability. Finally,its suggested that SOD activity might be as an index of cotton salt resistance breeding.