ABSTRACT Herbaceous peony (Paeonia lactiflora Pall.) is known as the flower phase. This phase is somewhat resistant to drought, but long-term drought and severe water shortage will affect its normal growth and development. In this study, physiological indices and the transcriptome of P. lactiflora were determined to clarify its physiological responses and gene expression changes under drought stress. The results showed that under drought stress, soluble sugar content, peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities, and chlorophyll, carotenoid and flavonoid contents were significantly increased, and soluble protein content, superoxide dismutase (SOD), glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), ascorbic acid (AsA) and glutathione (GSH) activity first increased and then decreased after day 14. Moreover, drought stress also significantly reduced chlorophyll content, photosynthesis and chlorophyll fluorescence parameters. Transcriptomic analysis revealed that compared with the Control, 10,747 differentially expressed genes (DEGs) were upregulated and 11,835 downregulated under drought stress. These DEGs were classified into three categories and 46 functional groups by GO function classification. The 3,179 DEGs were enriched into 128 pathways by KEGG pathway enrichment. The ROS system, chlorophyll degradation and photosynthetic capacity, as well as secondary pathways of biosynthesis and sugar metabolism were included. Additionally, relevant genes expressed in some metabolic pathways were discovered. These results provide a theoretical basis for understanding the responses of P. lactiflora to drought stress.

中文翻译：

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干旱胁迫对芍药（Paeonia lactiflora Pall.）生理反应和基因表达变化的影响

摘要 芍药（Paeonia lactiflora Pall.）被称为花期。此阶段具有一定的抗旱性，但长期干旱和严重缺水会影响其正常生长发育。本研究通过测定P.lactiflora的生理指标和转录组，阐明其在干旱胁迫下的生理反应和基因表达变化。结果表明，干旱胁迫下，可溶性糖含量、过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性以及叶绿素、类胡萝卜素和黄酮含量显着升高，可溶性蛋白含量、超氧化物歧化酶（SOD） , 谷胱甘肽还原酶 (GR), 脱氢抗坏血酸还原酶 (DHAR), 单脱氢抗坏血酸还原酶 (MDHAR), 抗坏血酸 (AsA) 和谷胱甘肽 (GSH) 活性在第 14 天后先升高后降低。此外，干旱胁迫也显着降低了叶绿素含量、光合作用和叶绿素荧光参数。转录组学分析显示，与对照相比，在干旱胁迫下，10,747 个差异表达基因 (DEG) 上调，11,835 个下调。这些DEGs通过GO功能分类分为三类46个功能组。通过KEGG通路富集将3179个DEGs富集到128个通路中。ROS 系统、叶绿素降解和光合能力，以及生物合成和糖代谢的次级途径都包括在内。此外，还发现了在一些代谢途径中表达的相关基因。