Glucosinolates in Brassica Species: Biosynthesis, Regulation, and Molecular Breeding

Glucosinolates (GSLs) are unique sulfur-containing secondary metabolites in Brassica crops that critically influence stress resistance, nutritional quality, and economic value. This review systematically summarizes the chemical classification, tissue-specific distribution, and conserved three-phase biosynthetic pathway of GSLs in Brassica species. We dissect the core MYB–MYC–WRKY transcriptional regulatory network, elucidate how whole-genome duplication-driven gene functional diversification shapes species-specific GSL accumulation patterns, and outline the multi-layered regulatory system integrating endogenous and exogenous signals. Furthermore, we consolidate recent advances in the genetic dissection of GSL traits and molecular breeding strategies for targeted trait improvement. Finally, we propose a three-tiered regulatory cascade model for GSL metabolism and highlight future research priorities to address current breeding bottlenecks. This work provides a systematic theoretical framework for functional research and precision breeding of GSL metabolism in Brassica crops.