Glutathione Peroxidase Regulation of Reactive Oxygen Species Level is Crucial for In Vitro Plant Differentiation
Glutathione Peroxidase Regulation of Reactive Oxygen Species Level is Crucial for In Vitro Plant Differentiation
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DOI：
10.1093/pcp/pcq082
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发表时间：
2010-07-01
影响因子：
4.9
通讯作者：
Perl, Avihai
中科院分区：
文献类型：
--
作者：
Faltin, Zehava;Holland, Doron;Perl, Avihai
磷脂过氧化氢谷胱甘肽过氧化物酶(PHGPx)在介导氧化胁迫的非生物和生物胁迫条件下在植物中过表达。为了研究它的生物学作用及其在植物中的抗逆性，我们试图获得高表达柑橘PHGPx(cit-PHGPx)的转基因植株(cit-PHGPx)。所有获得表达这种酶的再生植株的尝试都结构性地失败了。然而，当酶的催化活性被活性定点突变消除时，构成非活性cit-PHGPx的转基因植株成功地再生了。只有当转化基于非再生过程时，才能获得具有酶活性的cit-PHGPx的组成性表达。这些结果表明，抗氧化酶PHGPx的过度表达干扰了地上部器官的发生，并暗示了活性氧(ROS)参与了这一过程。利用转化β-雌二醇可诱导启动子的烟草植株获得的转基因烟草叶片，对cit-PHGPx的表达进行了时间依赖的诱导。Cit-PHGPx对不定芽形成的明显抑制作用仅限于再生过程的早期阶段。对再生过程中ROS水平的监测表明，在Cit-PHGPx诱导时，ROS的最低水平与最大的芽抑制水平相关。我们的结果清楚地证明了ROS在试管苗器官发生的早期阶段中的重要作用，以及PHGPx可能参与了在这一点上维持ROS的动态平衡。
Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is overexpressed in plants under abiotic and biotic stress conditions that mediate oxidative stress. To study its biological role and its ability to confer stress resistance in plants, we tried to obtain transgenic plants overexpressing citrus (Citrus sinensis) PHGPx (cit-PHGPx). All attempts to obtain regenerated plants expressing this enzyme constitutively failed. However, when the enzyme's catalytic activity was abolished by active site-directed mutagenesis, transgenic plants constitutively expressing inactive cit-PHGPx were successfully regenerated. Constitutive expression of enzymatically active cit-PHGPx could only be obtained when transformation was based on non-regenerative processes. These results indicate that overexpression of the antioxidant enzyme PHGPx interferes with shoot organogenesis and suggests the involvement of reactive oxygen species (ROS) in this process. Using transgenic tobacco (Nicotiana tabacum) leaves obtained from plants transformed with a beta-estradiol-inducible promoter, time-dependent induction of cit-PHGPx expression was employed. A pronounced inhibitory effect of cit-PHGPx on shoot formation was found to be limited to the early stage of the regeneration process. Monitoring the ROS level during regeneration revealed that upon cit-PHGPx induction, the lowest level of ROS correlated with the maximal level of shoot inhibition. Our results clearly demonstrate the essential role of ROS in the early stages of in vitro shoot organogenesis and the possible involvement of PHGPx in maintaining ROS homeostasis at this point.