Orchardgrass (Dactylis glomerata L.) is a popular cool-season perennial grass with a high production value, and orchardgrass seed is the fourth top-selling forage grass seed in the world. However, its yield and quality are often affected by flooding. To date, the molecular responses of orchardgrass to flooding were poorly understood. Here, we performed mRNA-seq to explore the transcriptomic responses of orchardgrass to a short term flooding (8 h and 24 h). There were 1454 and 565 differentially expressed genes identified in the 8 h and 24 h of flooding, respectively, compared to well control. GO functional enrichment analysis showed that oxidoreductase activity and oxidation-reduction process were highly present, suggesting that flooding induced the response to oxygen stress. Pathways enrichment analysis highlights the importance of glutathione metabolism, peroxidase, glycolysis and plant hormone signal transduction in response to flooding acclimation. Besides, the ROS clearance system is activated by significantly expressed glutathione S-transferase and genes encoding SOD and CAT (CAT1 and CDS2). The significant positive correlation between RNA sequencing data and a qPCR analysis indicated that the identified genes were credible. In the process of orchardgrass response to flooding stress, multiple differential genes and biological processes have participated in its acclimation to flooding, especially the biological processes involved in the removal of ROS. These results provide a basis for further research on the adaptation mechanism of orchardgrass to flood tolerance.

中文翻译：

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果园草 (Dactylis glomerata L.) 叶子对短期洪水响应的转录组分析

果园草（Dactylis glomerata L.）是一种受欢迎的冷季性多年生草本植物，产值很高，果园草种子是世界第四大畅销牧草种子。但其产量和品质常常受到洪水的影响。迄今为止，人们对果园草对洪水的分子反应知之甚少。在这里，我们进行了 mRNA-seq 来探索果园草对短期洪水（8 小时和 24 小时）的转录组反应。与井对照相比，淹水 8 小时和 24 小时分别鉴定出 1454 个和 565 个差异表达基因。GO功能富集分析表明氧化还原酶活性和氧化还原过程高度存在，表明水淹诱导了对氧胁迫的响应。通路富集分析强调了谷胱甘肽代谢、过氧化物酶、糖酵解和植物激素信号转导对洪水适应的重要性。此外，ROS清除系统由显着表达的谷胱甘肽S-转移酶和编码SOD和CAT（CAT1和CDS2）的基因激活。RNA测序数据与qPCR分析之间的显着正相关表明所鉴定的基因是可信的。在果园草应对洪水胁迫的过程中，多种差异基因和生物过程参与了其对洪水的适应，特别是清除ROS的生物过程。这些结果为进一步研究果园草耐洪适应机制提供了基础。