Generation of suspension cell cultures with high syringin content and anti-inflammatory activity through overexpressing glycotransferase SiUGT72BZ2 in Saussurea involucrata

Abstract

The snow lotus species Saussurea involucrata (Kar. & Kir.) Sch.Bip., an endangered traditional Chinese herb, belongs to a genus of the Asteraceae family. Syringin present in S. involucrata stands as one of the predominant bioactive compounds. However, the biosynthetic pathway of syringin remains largely elusive. Here, S. involucrata suspension cell culture was subjected to methyl jasmonate (MeJA) treatment, which stimulated the synthesis of syringin, increasing its content by up to 3.9-fold. Comparative transcriptome analysis revealed that genes involved in syringin biosynthesis were generally upregulated in response to MeJA. Furthermore, two candidate UDP-glycosyltransferase genes, SiUGT72BZ2 and SiUGT72CY1, were identified through phylogenetic tree and expression profiling analyses. Overexpression of SiUGT72BZ2 (BZ2_OE) and SiUGT72CY1 (CY1_OE) in S. involucrata suspension cell cultures led to 15.2- and 5.9-fold higher syringin levels than empty vector control cultures, respectively. Notably, upregulation of SiUGT72BZ2 enhanced the biosynthesis of coniferin as well. In contrast, only trace amounts of coniferin were present in control and CY1_OE cell cultures. Subsequent anti-inflammatory assays using lipopolysaccharide (LPS)-stimulated RAW264.7 cells demonstrated that the extracts from these cell cultures possessed remarkable anti-inflammatory properties. Most strikingly, the BZ2_OE cultures exhibited superior anti-inflammatory effects compared to the control and CY1_OE. In conclusion, our research has not only identified the key enzymes in syringin synthesis but also, through genetic engineering, has generated novel cell culture resources enriched with syringin and coniferin, and enhanced anti-inflammatory activities, highlighting the potential of S. involucrata cell culture as an alternative for wild snow lotus resources.