Key Laboratory of Silviculture and Conservation of the Ministry of Education, College of Forestry, Beijing Forestry University, Beijing 100083, China.
National Energy R&D Center for Non-food Biomass, Beijing Forestry University, Beijing 100083, China.
J Agric Food Chem. 2022 Jun 15;70(23):7095-7109. doi: 10.1021/acs.jafc.2c01672. Epub 2022 May 31.
Soapberry ( Gaertn.) pericarps are rich in valuable bioactive triterpenoid saponins. However, the saponin content dynamics and the molecular regulatory network of saponin biosynthesis in soapberry pericarps remain largely unclear. Here, we performed combined metabolite profiling and transcriptome analysis to identify saponin accumulation kinetic patterns, investigate gene networks, and characterize key candidate genes and transcription factors (TFs) involved in saponin biosynthesis in soapberry pericarps. A total of 54 saponins were tentatively identified, including 25 that were differentially accumulated. Furthermore, 49 genes putatively involved in sapogenin backbone biosynthesis and some candidate genes assumed to be responsible for the backbone modification, including 41 cytochrome P450s and 45 glycosyltransferases, were identified. Saponin-specific clusters/modules were identified by Mfuzz clustering and weighted gene coexpression network analysis, and one TF-gene regulatory network underlying saponin biosynthesis was proposed. The results of yeast one-hybrid assay and electrophoretic mobility shift assay suggested that SmbHLH2, SmTCP4, and SmWRKY27 may play important roles in the triterpenoid saponin biosynthesis by directly regulating the transcription of in the soapberry pericarp. Overall, these findings provide valuable information for understanding the molecular regulatory mechanism of saponin biosynthesis, enriching the gene resources, and guiding further research on triterpenoid saponin accumulation in soapberry pericarps.
无患子果皮富含有价值的生物活性三萜皂苷。然而，无患子果皮中皂苷含量的动态变化以及皂苷生物合成的分子调控网络在很大程度上仍不清楚。在这里，我们进行了组合代谢组学和转录组学分析，以确定皂苷的积累动力学模式，研究基因网络，并鉴定与无患子果皮中皂苷生物合成相关的关键候选基因和转录因子（TFs）。共鉴定出 54 种皂苷，其中 25 种为差异积累。此外，还鉴定出了 49 个推测参与皂素骨架生物合成的基因，以及一些假定负责骨架修饰的候选基因，包括 41 个细胞色素 P450 和 45 个糖基转移酶。通过 Mfuzz 聚类和加权基因共表达网络分析鉴定了皂苷特异性聚类/模块，并提出了一个与皂苷生物合成相关的 TF-基因调控网络。酵母单杂交试验和电泳迁移率变动分析的结果表明，SmbHLH2、SmTCP4 和 SmWRKY27 可能通过直接调节无患子果皮中 的转录，在三萜皂苷生物合成中发挥重要作用。总的来说，这些发现为理解皂苷生物合成的分子调控机制、丰富基因资源以及指导无患子果皮中三萜皂苷积累的进一步研究提供了有价值的信息。
