Integrated hormonal signaling and transcriptional networks reveal mechanisms of adventitious organogenesis in bitter gourd (Momordica charantia L.)

Adventitious shoot regeneration is crucial for advancing micropropagation and genetic transformation in bitter gourd; however, its underlying molecular regulatory mechanisms remain poorly understood. To systematically elucidate the genetic and physiological basis of regenerative capacity, this study employed high-regeneration genotype 25–15 and low-regeneration genotype 07–11 as materials, utilizing endogenous hormone profiling, histological examination, and transcriptome sequencing to uncover the key regulatory mechanisms during the regeneration process. The results demonstrated that after optimizing the explant type, medium formulation, and dark treatment conditions for genotype 25–15, the shoot induction rate reached 77.56%. Its high regeneration efficiency stemmed from the formation of compact meristematic clusters in the early stage, rapid integration of the vascular system, and the dynamic change of the indole-3-acetic acid (IAA)/zeatin (ZT) ratio that first increases and then decreases during the induction and differentiation stages. Transcriptomic analysis revealed that differentially expressed genes (DEGs) were significantly enriched in such pathways as zeatin biosynthesis, starch-sucrose metabolism, and hormone signal transduction, while weighted gene co-expression network analysis (WGCNA) identified 20 hub genes—including growth-regulating factors ( GRFs ), CUP-SHAPED COT YLEDON 2-like ( CUC2 ), SCARECROW-like protein ( SCR ) and AP2-like ethylene-responsive transcription factor ANT ( ANT ). Therefore, we propose that hub genes, as core regulatory nodes in adventitious shoot regeneration, form a synergistic network with DEGs in key metabolic pathways. By precisely regulating endogenous hormone dynamic balance and meristem initiation-differentiation, they jointly drive efficient adventitious shoot regeneration of bitter gourd. These findings provide theoretical and technical support for Cucurbitaceae genetic transformation, germplasm innovation, and genotype-independent regeneration system establishment.