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为揭示核桃抗寒机理,确定核桃抗寒性鉴定适宜的生化指标,以展叶期抗寒性不同的哈特雷、晋龙1号和晋龙2号3个品种1年生枝条的叶片为材料,测定了1℃低温下抗氧化酶活性及超氧阴离子(O2-·)含量的变化,并采用透射电子显微镜观察低温逆境对抗寒性差异大的哈特雷和晋龙2号叶肉细胞超微结构的影响.结果表明:低温胁迫前后抗寒性强的哈特雷叶片中超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性最高,超氧阴离子含量最低,叶肉细胞超微结构较稳定,叶片没有明显冷害症状.抗寒性差的晋龙2号随着低温胁迫时间的延长,3种抗氧化酶活性的下降幅度最大,O2-·含量始终处于高水平;胁迫72 h时细胞叶绿体普遍膨胀,基粒片层变薄,数目减少,部分叶绿体被膜及质膜清晰度下降,部分顶端小叶叶缘呈水浸状,表现出冷害症状.可见,低温逆境下核桃叶肉细胞超微结构的稳定性与其品种的抗寒性密切相关.SOD、POD活性以及O2-·含量可作为展叶期核桃抗寒性鉴定的生化指标;低温胁迫下核桃叶片细胞内膜系统的损伤与活性氧积累之间可能存在一定的相互关系.
In order to reveal the mechanism of walnut cold hardiness and determine the suitable biochemical indexes to appraise the cold resistance of walnut, the leaves of 3 annual branches of Hartley, Jinlong 1 and Jinlong 2 with different cold resistance in leaf expo were used as materials , The changes of antioxidant enzyme activity and superoxide anion (O2-) content at 1 ℃ were measured, and the ultrastructure of Hatley and Jinlong 2 mesophyll cells with different cold resistance were observed by transmission electron microscope The results showed that SOD activity and peroxidase (POD) activities of Hatter’s leaves with the highest cold-hardiness before and after low temperature stress were the highest, the content of superoxide anion was the lowest, the ultrastructure of mesophyll cells More stable and no obvious symptoms of chilling injury in leaves.With cold stress, Jinlong 2 had the largest decline in the activity of three antioxidant enzymes, and the content of O2- · was always at a high level. After 72 h of stress, Chloroplasts generally expanded, the number of grana lamellae decreased, the number of chloroplast capsule and plasma membrane clarity decreased, some of the top lobular leaflets were flooded, showing chilling injury symptoms can be seen under low temperature walnut leaf cell ultrastructure The stability with it Cold tolerance of Siberian chinense L., SOD, POD activity and O2- · content could be used as biochemical indexes to identify the cold resistance of walnut in leaf-developing stage. There might exist some differences between the injury of inner cell membrane and the accumulation of reactive oxygen species in walnut leaves under low temperature stress A certain relationship.