The rhizome-expressed gene PgAHL1 coordinates vegetative growth and ginsenoside biosynthesis

Panax ginseng C. A. Meyer, a perennial medicinal herb of great therapeutic and economic value, develops rhizomes that serve as critical junctions connecting aerial and subterranean tissues while harboring multiple meristematic centers. These rhizomes play essential roles in coordinating the balance between vegetative and reproductive growth to complete the life cycle of this perennial plant. In this study, we systematically identified 50 AHL (AT-hook motif nuclear localized) genes in the P. ginseng genome, with particular focus on PgAHL1 , which showed both rhizome-specific expression patterns and high sequence homology to Arabidopsis thaliana AHL15 . Through promoter activity analysis, we demonstrated that PgAHL1 exhibited predominant expression in axillary meristematic tissues of Nicotiana benthamiana . Functional characterization in A. thaliana revealed that PgAHL1 promoted vegetative growth (evidenced by increased rosette leaf number, primary rosette leaf branch height, and total branch number), while significantly suppressed reproductive development (manifested as reduced inflorescence and silique numbers). More importantly, in transgenic ginseng callus, PgAHL1 overexpression led to a remarkable enhancement in both callus growth rate and the biosynthesis of minor ginsenosides Ro and Rg 2 . Integrated multi-omics analyses, combining RNA-seq and DAP-seq, identified that PgAHL1 directly regulated an extensive gene network, including key cell differentiation-related genes ( ACC1 , CUV1/2 , GTE4 , RID2 , PAS1 ) and ginsenoside biosynthesis genes ( HMGCS-4 , HMGR-3 , β-AS-5 , UGT71A27–5 , SE-8 ). These findings elucidate the coordinated regulatory mechanisms of AHL genes in ginseng rhizome development and provide a promising genetic resource for enhancing minor ginsenoside content and quality. • PgAHL1 , homologous to AtAHL15 , is highly expressed in ginseng rhizomes. • PgAHL1 promoter activity is most prominent in tobacco axillary meristem tissues. • PgAHL1 promotes vegetative growth while repressing reproductive development. • PgAHL1 regulates minor ginsenoside biosynthesis and callus growth.