Temperature and Light Regimes Shape Seasonal Variation in Glucosinolate Hydrolysis in Red Cabbage

Glucosinolate hydrolysis in <i>Brassica oleracea</i> can yield health-promoting isothiocyanates but often results in less bioactive nitriles and epithionitriles. Here, the impact of temperature, light intensity, and photoperiod on glucosinolate metabolism was investigated in red cabbage at two developmental stages: sprouts and mature plants. Controlled simulations of summer and autumn cabbage cultivation revealed that high light and warm temperatures (16-h photoperiod, 23.4 mol m^-2 d^-1, 25 °C) favored ITC formation, while cold, short-day conditions (8h photoperiod, 7.0 mol m^-2 d^-1, max 15 °C) enhanced nitriles and epithionitriles. The hydrolysis outcome was associated with the differential expression of specifier and modifier proteins (BoESP1-3, BoESM1). Investigation of individual growing conditions indicated that light is the driving factor regulating specifier proteins, thereby shifting the glucosinolate hydrolysis outcome. Proteome and transcript analyses confirmed the functional link between environmental shifts and glucosinolate metabolic responses. These findings highlight the potential to improve the nutritional quality of <i>Brassica</i> crops through targeted cultivation strategies.