GeARF5/GeIAA33-GeSWEET14 module balances the secondary metabolic biosynthesis to increase the yield and quality in Gastrodia elata

Gastrodia elata is an important edible and medicinal plant, and its yield is a significant factor limiting the industry's development. The number of branches produced by vegetative propagation corms (VPCs) is a limiting factor for the yield of G. elata. Hormonal signals, along with sucrose and starch biosynthesis, are key factors potentially influencing VPC formation. However, the mechanisms underlying VPC formation in G. elata remain poorly understood. In this study, we identified a member of the SWEET family, GeSWEET14, through single-stem/multi-stem (SS/MS) transcriptome screening. GeSWEET14 has the potential to increase both VPC formation and the yield of G. elata by promoting sucrose and starch biosynthesis while simultaneously reducing gastrodin biosynthesis. Further results demonstrated that the auxin increases the VPC formation by activating GeARF5-GeSWEET14 expression. In contrast, the auxin signaling inhibitor GeIAA33 was found to be upregulated in the OE-GeSWEET14 transgenic lines. GeIAA33 interacts with GeARF5 both in vivo and in vitro, attenuating its transcriptional activation of GeSWEET14 and thus establishing a feedback regulatory mechanism. Moreover, GeARF5 promotes the accumulation of sucrose and starch by binding to the promoters of GeISA3 and GeglgB1. Additionally, GeARF5 enhances gastrodin biosynthesis by binding to the promoters of GePAL1 and GeGT3-1. Collectively, these findings elucidate the role of the GeARF5/GeIAA33-GeSWEET14 module in VPC formation and secondary metabolite accumulation, providing a foundation for the genetic improvement of G. elata germplasm resources.