Overexpression of the patatin-related phospholipase A gene, PgpPLAIIIβ, in ginseng adventitious roots reduces lignin and ginsenoside content while increasing fatty acid content

Abstract

The patatin-related phospholipase AIII (pPLAIII) gene family plays a crucial role in regulating cell elongation, cell wall composition, and lipid metabolism in plants, making it a promising target for agricultural and commercial innovations. This study provides a comprehensive functional analysis of PgpPLAIIIβ in Panax ginseng, a medicinal plant of substantial economic importance. Overexpression of PgpPLAIIIβ led to significant morphological changes, including shorter, thicker roots, and an 8% reduction in lignin content, while cellulose levels remained unaffected. The reduced lignification was attributed to the downregulation of key lignin biosynthetic genes and decreased hydrogen peroxide accumulation. A yeast two-hybrid assay identified a CCCH-type zinc finger protein as a potential PgpPLAIIIβ interactor, pointing to a mechanism that may underlie the changes in root structure and lignin deposition. Metabolite analysis revealed a 7.6% increase in total free fatty acid content, with notable increases in palmitic and linoleic acids, alongside a 28% reduction in ginsenoside levels, linked to the downregulation of triterpenoid biosynthetic genes. These findings demonstrate that PgpPLAIIIβ is a key regulator of root architecture, lignin composition, and secondary metabolite balance in ginseng. The metabolic engineering of PgpPLAIIIβ could be a powerful strategy to improve root traits, optimize lignin deposition, and enhance metabolite profiles, ultimately boosting the commercial and medicinal value of ginseng.