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为探究乌拉尔甘草(Glycyrrhiza uralensis)对干旱胁迫的生理及分子响应机制，本研究采用聚乙二醇6000 (polyethylene glycol 6000, PEG-6000)模拟干旱的方法，测定乌拉尔甘草幼苗光合指标和抗氧化酶活性，并进行转录组测序分析。结果表明：干旱胁迫至7 d时，甘草的净光合速率(net photosynthetic rate, Pn)、气孔导度(stomatal conductance, Gs)、蒸腾速率(transpiration rate, Tr)到达最低值。相对叶绿素含量(soil and plant analyzer develotrnent, SPAD)表现为先上升后下降。干旱引起甘草的氧化应激，处理1 d时提高了叶片中过氧化氢酶(catalase, CAT)活性，降低了根中CAT活性。处理7 d时提高了根中过氧化物酶(peroxide, POD)活性，降低了根中超氧化物歧化酶(superoxide dismutase, SOD)活性。转录组分析结果显示，甘草地上部分和地下部分分别有差异表达基因(differentially expressed genes, DEGs) 7 500和5 298个；基因本体(gene ontology, GO)富集结果表明，地上和地下两部分的DEGs在三大类的分布基本一致，均被显著富集到细胞过程、代谢过程、细胞结构、催化活性、转导活性等功能；京都基因与基因组百科全书(Kyoto Encyclopedia of Genes and Genomes, KEGG)代谢途径富集分析表明，地上部分和地下部分DEGs均显著富集在转录因子、蛋白激酶、苯丙烷类生物合成和细胞色素P450等代谢途径。转录调控网络分析预测表明，ERF (ethylene responsive factor)、bHLH (basic helix-loop-helix)、NAC (NAM/ATAF/CUC)、MYB (v-myb avian myeloblastosis viral oncogene homolog)和WRKY 类转录因子可能与甘草次级代谢产物相关基因存在转录调控关系。综上，本研究揭示了干旱胁迫对甘草生理特性的影响，分析了不同部位基因的表达，可为今后研究甘草抗旱机制提供有价值的信息。“,”To explore the physiological and molecular mechanisms of Glycyrrhiza uralensis under drought stress simulated by polyethylene glycol 6000 (PEG-6000), transcriptome sequencing, photosynthetic characteristics, and antioxidant enzyme activity analyses were performed. The results showed that the values of net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) were the lowest at 7 d under drought stress. Relative chlorophyll content [soil and plant analysis development (SPAD)] first increased and then decreased. Oxidative stress was induced by drought stress on G. uralensis. Catalase (CAT) activity of the leaves increased, whereas CAT activity of the roots decreased after 1 day of treatment. After 7 days of treatment, peroxide (POD) and superoxide dismutase (SOD) activities increased and decreased in the roots, respectively. Transcriptomic analysis identified a total of 7 500 differentially expressed genes (DEGs) in the aboveground parts and 5 298 DEGs in the underground parts. Gene ontology (GO) enrichment results showed that the DEGs of the aboveground and underground parts were both significantly enriched for cellular process, metabolic process, cell structure, catalytic activity, transporter activity, etc. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that DEGs in the aboveground and underground were both significantly enriched in transcription factors, protein kinases, phenylpropanoid biosynthesis, and cytochrome P450, etc. Transcriptional regulatory network analysis predicted that transcription factors such as ethylene responsive factor (ERF), basic helix-loop-helix (bHLH), NAM/ATAF/CUC (NAC), v-myb avian myeloblastosis viral oncogene homolog (MYB), and WRKY may be involved in regulating the expression of secondary metabolism genes. In conclusion, this study revealed the effects of drought stress on physiological characteristics of G. uralensis, and analyzed gene expression profiles in different parts of G. uralensis. Our results provide valuable information for understanding drought-resistance mechanisms of G. uralensis.