As a conserved microRNA (miRNA) family in plants, miR408 is known to be involved in different abiotic stress responses, including drought. Interestingly, some studies indicated a species- and/or cultivar-specific drought-responsive characteristic of miR408 in plant drought stress. Moreover, the functions of miR408 in perennial grass species are unknown. In this study, we investigated the role of miR408 in perennial ryegrass (Lolium perenne L.) by withholding water for 10 days for both wild type and transgenic plants with heterologous expression of a rice (Oryza sativa L.) miR408 gene, Os-miR408. The results showed that transgenic perennial ryegrass plants displayed morphological changes under normal growth conditions, such as curl leaves and sunken stomata, which could be related to decreased leaf water loss. Moreover, transgenic perennial ryegrass exhibited improved drought tolerance, as demonstrated by maintaining higher leaf relative water content (RWC), lower electrolyte leakage (EL) and less lipid peroxidation compared to WT plants under drought stress. Furthermore, the transgenic plants showed higher antioxidative capacity under drought. These results showed that the improved drought tolerance in Os-miR408 transgenic plants could be due to leaf morphological changes favoring the maintenance of water status and to increased antioxidative capacity protecting against the reactive oxygen species damages under stress. These findings implied that miR408 could serve as a potential target for genetic manipulations to engineer perennial grass plants for improved water stress tolerance. This article is protected by copyright. All rights reserved.

中文翻译：

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Os-microRNA408的过表达增强多年生黑麦草的耐旱性

作为植物中一个保守的 microRNA (miRNA) 家族，已知 miR408 参与不同的非生物胁迫反应，包括干旱。有趣的是，一些研究表明 miR408 在植物干旱胁迫中具有物种和/或品种特异性的干旱响应特征。此外，miR408 在多年生草种中的功能尚不清楚。在这项研究中，我们通过对具有水稻 (Oryza sativa L.) miR408 基因 Os-miR408 的异源表达的野生型和转基因植物停水 10 天，研究 miR408 在多年生黑麦草 (Lolium perenne L.) 中的作用. 结果表明，转基因多年生黑麦草植物在正常生长条件下表现出叶片卷曲、气孔凹陷等形态变化，这可能与叶片水分流失减少有关。而且，与干旱胁迫下的野生型植物相比，转基因多年生黑麦草表现出更高的耐旱性，这通过保持较高的叶片相对含水量 (RWC)、较低的电解质泄漏 (EL) 和较少的脂质过氧化来证明。此外，转基因植物在干旱条件下表现出更高的抗氧化能力。这些结果表明，Os-miR408 转基因植物的耐旱性提高可能是由于叶片形态变化有利于维持水分​​状态，以及增强的抗氧化能力保护免受胁迫下的活性氧损伤。这些发现表明 miR408 可以作为基因操作的潜在目标，以改造多年生草本植物以提高水胁迫耐受性。本文受版权保护。版权所有。