Glucosinolate Biosynthesis, Hydrolysis, Transport, and Application Trade-Offs in Agriculture and Food Science

Glucosinolates (GSLs) are sulfur- and nitrogen-containing specialized metabolites characteristic of the Brassicales, especially Brassicaceae crops. The agricultural and nutritional significance of GSLs is not determined by total content alone. Rather, it reflects the combined effects of chemical diversity, organ-specific accumulation, and hydrolytic conversion. Biosynthesis shapes the classes and side-chain structures of GSLs, transport regulates their allocation to different tissues, and myrosinase-mediated hydrolysis generates bioactive products. These coordinated processes ultimately affect plant defense, crop flavor, nutritional quality, and potential toxicity. In this review, we systematically summarize the biosynthetic pathways, hydrolysis mechanisms, and transport regulation of GSLs, emphasizing how these mechanisms jointly determine their biological functions and application potential. We further discuss the roles of GSLs in crop defense, rapeseed feed quality, vegetable flavor formation, functional food development, and food safety evaluation. Rather than pursuing a simple increase or decrease in total GSL levels, future GSL regulation should focus on crop-, tissue-, compound-, and product-specific strategies. Multi-gene regulatory networks, tissue-specific allocation, and product-specific safety assessment will be essential for balancing plant defense, agricultural productivity, food quality, and human health benefits.