外源H2O2对湖北海棠根系线粒体膜透性和细胞核DNA的影响

用0．024％（V／V）H2O2处理湖北海棠（Malus hupehensis Rehd．）实生苗根系，30min后，根系线粒体膜通透，陛明显增大，线粒体膜电位（△ψm）和线粒体内Cyt c／a吸光度比值下降；60min后，根系细胞核DNA发生片段化降解。经荧光染料吖啶橙染色后，可见H2O2处理60min以上的根系压片中出现了清晰致密的黄绿色荧光宽，呈现出细胞程序，陛死亡（PCD）的特征。

The Effect of Exogenous H2O2 on Mitochondrial Membrane Permeability and Cell Nuclear DNA in Roots of Malus hupehensis

To investigate the changes in mitochondrial permeability transition, DNA degradation and cell death, seedling roots of Malus hupehensis Rehd. were treated directly with exogenous H(2)O(2). The results showed that mitochondrial permeability increased obviously by 0.024% (V/V) H(2)O(2) treatment for 30 min and increased continuously during the time of H(2)O(2) treatment (Fig.1). At the time of mitochondrial permeability increasing, mitochondrial membrane potential (Delta psi m) decreased (Fig.2). In addition, the ratio of Cyt c/a became lower (Fig.3) when mitochondrial permeability increased and Delta psi m decreased. DNA fragments were detected at the 60 min of H(2)O(2) treatment, the number of fragments increased after 60 min of H(2)O(2) treatment (Fig.4). Granular nuclei stained irregularly were evident in root slices stained by acridine orange (Fig.5). This indicates H(2)O(2) can induce programmed cell death by increasing mitochondrial permeability and decreasing Delta psi m in the root of Malus hupehensis Rehd.