Data_Sheet_1_Metabolite Profiling and Transcriptome Analysis Explains Difference in Accumulation of Bioactive Constituents in Licorice (Glycyrrhiza uralensis) Under Salt Stress.zip

Salinity stress significantly affects the contents of bioactive constituents in licorice Glycyrrhiza uralensis. To elucidate the molecular mechanism underlying the difference in the accumulation of these constituents under sodium chloride (NaCl, salt) stress, licorice seedlings were treated with NaCl and then subjected to an integrated transcriptomic and metabolite profiling analysis. The transcriptomic analysis results identified 3,664 differentially expressed genes (DEGs) including transcription factor family MYB and basic helix-loop-helix (bHLH). Most DEGs were involved in flavonoid and terpenoid biosynthesis pathways. In addition, 121 compounds including a triterpenoid and five classes of flavonoids (isoflavone, flavone, flavanone, isoflavan, and chalcone) were identified, and their relative levels were compared between the stressed and control groups using data from the ultrafast liquid chromatography (UFLC)–triple quadrupole–time of flight–tandem mass spectrometry (TOF–MS/MS) analysis. Putative biosynthesis networks of the flavonoids and triterpenoids were created and combined with structural DEGs such as phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase [4CL], cinnamate 4-hydroxylase [C4H], chalcone synthase [CHS], chalcone-flavanone isomerase [CHI], and flavonoid-3′,5′ hydroxylase (F3′,5′H) for flavonoids, and CYP88D6 and CYP72A154 for glycyrrhizin biosynthesis. Notably, significant upregulation of UDP-glycosyltransferase genes (UGT) in salt-stressed licorice indicated that postmodification of glycosyltransferase may participate in downstream biosynthesis of flavonoid glycosides and triterpenoid saponins. Accordingly, the expression trend of the DEGs is positively correlated with the accumulation of glycosides. Our study findings indicate that key DEGs and crucial UGT genes co-regulate flavonoid and saponin biosynthesis in licorice under salt stress.

盐胁迫（salinity stress）可显著影响乌拉尔甘草（Glycyrrhiza uralensis）中生物活性成分的含量。为阐明氯化钠（sodium chloride，NaCl，盐）胁迫下此类成分积累差异的分子机制，本研究对甘草幼苗施加NaCl处理，随后开展整合转录组（transcriptomic）与代谢谱分析。转录组分析共鉴定出3664个差异表达基因（differentially expressed genes，DEGs），涵盖MYB转录因子家族与碱性螺旋-环-螺旋（basic helix-loop-helix，bHLH）家族；多数差异表达基因参与黄酮类（flavonoid）与萜类（terpenoid）生物合成通路。此外，本研究还鉴定出121种化合物，包括1种三萜类（triterpenoid）以及5类黄酮类物质：异黄酮（isoflavone）、黄酮（flavone）、黄烷酮（flavanone）、异黄烷（isoflavan）与查尔酮（chalcone）；借助超快速液相色谱-三重四极杆-飞行时间串联质谱（ultrafast liquid chromatography，UFLC–triple quadrupole–time of flight–tandem mass spectrometry，TOF–MS/MS）分析数据，研究人员比较了胁迫组与对照组间各化合物的相对含量。本研究构建了黄酮类与三萜类的推定生物合成网络，并将其与结构型差异表达基因相结合：黄酮类相关结构基因包括苯丙氨酸解氨酶（phenylalanine ammonia-lyase，PAL）、4-香豆酸-CoA连接酶[4CL]、肉桂酸-4-羟化酶[C4H]、查尔酮合酶[CHS]、查尔酮-黄烷酮异构酶[CHI]以及黄酮-3′,5′-羟化酶（F3′,5′H）；甘草酸生物合成相关结构基因为CYP88D6与CYP72A154。值得注意的是，盐胁迫甘草中UDP-糖基转移酶基因（UDP-glycosyltransferase，UGT）的表达量显著上调，表明糖基化修饰可能参与黄酮苷与三萜皂苷的下游生物合成过程。据此，差异表达基因的表达趋势与糖苷类物质的积累呈正相关。本研究结果表明，在盐胁迫下，关键差异表达基因与核心UGT基因共同调控甘草中黄酮类与皂苷类物质的生物合成。