Maruta Takanori, Inoue Takahiro, Noshi Masahiro, Tamoi Masahiro, Yabuta Yukinori, Yoshimura Kazuya, Ishikawa Takahiro, Shigeoka Shigeru
Department of Advanced Bioscience, Kinki University, Nara, Japan.
Biochim Biophys Acta. 2012 Dec;1820(12):1901-7. doi: 10.1016/j.bbagen.2012.08.003. Epub 2012 Aug 18.
Reactive oxygen species (ROS) are not only cytotoxic compounds leading to oxidative damage, but also signaling molecules for regulating plant responses to stress and hormones. Arabidopsis cytosolic ascorbate peroxidase 1 (APX1) is thought to be a central regulator for cellular ROS levels. However, it remains unclear whether APX1 is involved in plant tolerance to wounding and methyl jasmonate (MeJA) treatment, which are known to enhance ROS production.
We studied the effect of wounding and MeJA treatment on the levels of H(2)O(2) and oxidative damage in the Arabidopsis wild-type plants and knockout mutants lacking APX1 (KO-APX1).
The KO-APX1 plants showed high sensitivity to wounding and MeJA treatment. In the leaves of wild-type plants, H(2)O(2) accumulated only in the vicinity of the wound, while in the leaves of the KO-APX1 plants it accumulated extensively from damaged to undamaged regions. During MeJA treatment, the levels of H(2)O(2) were much higher in the leaves of KO-APX1 plants. Oxidative damage in the chloroplasts and nucleus was also enhanced in the leaves of KO-APX1 plants. These findings suggest that APX1 protects organelles against oxidative stress by wounding and MeJA treatment.
This is the first report demonstrating that H(2)O(2)-scavenging in the cytosol is essential for plant tolerance to wounding and MeJA treatment.
活性氧（ROS）不仅是导致氧化损伤的细胞毒性化合物，也是调节植物对胁迫和激素反应的信号分子。拟南芥胞质抗坏血酸过氧化物酶1（APX1）被认为是细胞ROS水平的核心调节因子。然而，APX1是否参与植物对创伤和茉莉酸甲酯（MeJA）处理的耐受性仍不清楚，已知创伤和MeJA处理会增强ROS的产生。
我们研究了创伤和MeJA处理对拟南芥野生型植株和缺乏APX1的敲除突变体（KO-APX1）中H₂O₂水平和氧化损伤的影响。
KO-APX1植株对创伤和MeJA处理表现出高度敏感性。在野生型植株的叶片中，H₂O₂仅在伤口附近积累，而在KO-APX1植株的叶片中，它从受损区域到未受损区域广泛积累。在MeJA处理期间，KO-APX1植株叶片中的H₂O₂水平要高得多。KO-APX1植株叶片中叶绿体和细胞核的氧化损伤也有所增强。这些发现表明，APX1通过创伤和MeJA处理保护细胞器免受氧化应激。
这是第一份证明胞质中清除H₂O₂对于植物对创伤和MeJA处理的耐受性至关重要的报告。
