Department of Biotechnology, Bioenergy Research Center, Interdisciplinary Program of Bioenergy and Biomaterials, Chonnam National University, Gwangju, South Korea.
J Pineal Res. 2013 Apr;54(3):258-63. doi: 10.1111/j.1600-079X.2012.01029.x. Epub 2012 Aug 1.
To examine whether melatonin-rich plants can defend against oxidative stress, we subjected melatonin-rich transgenic (MRT) rice plants to the singlet-oxygen-generating herbicide butafenacil. Both MRT and transgenic control (TC; expressing the vector only) rice seeds germinated and grew equally well in continuous dark on half-strength Murashige and Skoog (MS) medium containing 0.1 μm butafenacil. However, after transferring the seedlings to light, the TCs rapidly necrotized, whereas the MRT seedlings showed resistant phenotypes. Seven-day-old MRT seedlings treated with 0.1 μm butafenacil were resistant to the herbicide and contained high chlorophyll levels and low malondialdehyde and hydrogen peroxide contents compared with the TCs. As they did before the herbicide treatment, the MRT plants also produced much more melatonin after the herbicide treatment than the TCs. In addition, the MRT plants exhibited higher superoxide dismutase and catalase activities before and after the herbicide treatment compared with the TCs. This is the first report showing that MRT plants exhibit resistance against a peroxidizing herbicide that acts by generating reactive oxygen species (ROS) that kill plants. This result indicates that melatonin scavenges ROS efficiently in vivo in the transgenic plants, leading to oxidative stress resistance.
为了研究富含褪黑素的植物是否能抵御氧化应激，我们用产生单线态氧的除草剂草丁膦处理富含褪黑素的转基因（MRT）水稻植株。在含有 0.1μm 草丁膦的半强度 Murashige 和 Skoog（MS）培养基中，MRT 和转基因对照（TC；仅表达载体）的水稻种子在连续黑暗中同样良好地发芽和生长。然而，当将幼苗转移到光照下时，TCs 迅速坏死，而 MRT 幼苗则表现出抗性表型。与 TC 相比，用 0.1μm 草丁膦处理的 7 天大的 MRT 幼苗对除草剂有抗性，并且含有高叶绿素水平和低丙二醛和过氧化氢含量。与除草剂处理前一样，MRT 植物在除草剂处理后也比 TC 产生更多的褪黑素。此外，与 TC 相比，MRT 植物在除草剂处理前后表现出更高的超氧化物歧化酶和过氧化氢酶活性。这是第一个表明 MRT 植物对通过产生杀死植物的活性氧（ROS）而起作用的过氧化除草剂表现出抗性的报告。这一结果表明，褪黑素在转基因植物体内有效地清除了 ROS，从而导致了对氧化应激的抗性。
