Virus-Induced Gene Silencing Revealed ZoWRKY21 Regulates 6-Gingerol Biosynthesis in Ginger

Abstract 6-gingerol is the predominant constituent of Zingiber officinale (ginger) extract. The WRKY transcription factor families have been shown to be involved in the regulation of plant secondary metabolites. Here, virus-induced gene silencing (VIGS) method with barley stripe mosaic virus (BSMV) was used to investigate the regulatory role of ZoWRKY21 in modulating 6-gingerol biosynthesis. The expression levels of ZoWRKY21 and 6-gingerol biosynthetic relative enzyme genes including ZoPAL, ZoC4H, Zo4CL and ZoCCoAOMT in different tissues in BSMV::ZoWRKY21-inoculated plants were significantly reduced, indicating the viral vector exhibited a silencing effect. Downregulation of ZoWRKY21 significantly affected the expression of Zo4CL and ZoCCoAOMT. Additionally, the content of 6-gingerol was significantly reduced in BSMV: ZoWRKY21 plants compared to the control groups, which further verifies the positive regulatory function of ZoWRKY21 and ZoCCoAOMT or Zo4CL in 6-gingerol biosynthesis. The results provide clarification of the role of ZoWRKY21 and 6-gingerol biosynthetic relative enzyme genes in the biosynthetic pathway of 6-gingerol.