Abstract microRNA398 (miR398) is known to be involved in response to abiotic stress in some plant species through transcriptionally regulating its targets, Cu/Zn superoxide dismutase (CSD). However, the role of miR398 has not yet been characterized in horticultural plants. It also remains unclear as how miR398 regulate antioxidant system and photosynthesis under salinity. To address this issue, we generated transgenic tomato lines overexpressing its own miR398 and exposed them to salt stress. Overexpression of sly-miR398b inhibited the plant growth under salinity, including less shoot and root biomass and shorter plant height. In addition, the transgenic plants accumulated more O2 − under normal and saline conditions, and consequently suffered from more severe oxidative damage. Further analyses revealed that overexpression of sly-miR398b downregulated the expression of CSD, APX and CAT, leading to the reduced activities of SOD, APX and CAT, and the contents of reduced glutathione. In addition, the transgenic plants exhibited lower rates of photosynthesis and higher photoinhibition under salinity in comparison with the wild type plants. The data provide new evidence on the miR398 mediated ROS metabolism network underlying salt stress response in tomato.

中文翻译：

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sly-miR398b的过表达可能通过调节番茄的抗氧化系统和光合作用增加盐敏感性

摘要 microRNA398 (miR398) 已知通过转录调节其靶标 Cu/Zn 超氧化物歧化酶 (CSD) 参与一些植物物种对非生物胁迫的响应。然而，尚未在园艺植物中表征 miR398 的作用。miR398 如何在盐度下调节抗氧化系统和光合作用也不清楚。为了解决这个问题，我们生成了过表达其自身 miR398 的转基因番茄系，并将它们暴露于盐胁迫下。sly-miR398b 的过表达抑制了盐度下的植物生长，包括较少的地上部和根生物量以及较短的植物高度。此外，转基因植物在正常和盐水条件下积累了更多的 O2 - ，因此遭受更严重的氧化损伤。进一步的分析表明，sly-miR398b 的过表达下调了 CSD、APX 和 CAT 的表达，导致 SOD、APX 和 CAT 的活性降低，以及还原型谷胱甘肽的含量。此外，与野生型植物相比，转基因植物在盐度下表现出较低的光合作用速率和较高的光抑制。该数据为 miR398 介导的 ROS 代谢网络提供了新的证据，该网络是番茄盐胁迫反应的基础。