Epigenetic Regulation of Glucosinolate Biosynthesis: Mechanistic Insights and Breeding Prospects in Brassicaceae

Glucosinolates (GSLs) are nitrogen- and sulfur-containing secondary metabolites central to the defense, development, and environmental responsiveness of Brassicaceae species. While the enzymatic steps and transcriptional networks underlying GSL biosynthesis have been extensively characterized, mounting evidence reveals that chromatin-based processes add a critical, yet underexplored, layer of regulatory complexity. Recent studies highlight the roles of DNA methylation, histone modifications, and non-coding RNAs in modulating the spatial and temporal expression of GSL biosynthetic genes and their transcriptional regulators in response to developmental cues and environmental signals. This review provides a comprehensive overview of GSL classification, biosynthetic pathway architecture, transcriptional regulation, and metabolite transport, with a focus on emerging epigenetic mechanisms that shape pathway plasticity. We also discuss how these insights may be leveraged in precision breeding and epigenome engineering, including the use of CRISPR/dCas9-based chromatin editing and epigenomic selection, to optimize GSL content, composition, and stress resilience in cruciferous crops. Integrating transcriptional and epigenetic regulation thus offers a novel framework for the dynamic control of specialized metabolism in plants.