Quantitative trait loci analysis of non-enzymatic glucosinolate degradation rates in Brassica oleracea during food processing

Epidemiological and mechanistic studies show health-promoting effects of glucosinolates and their breakdown products. In literature, differences in non-enzymatic glucosinolate degradation rates during food processing between different vegetables are described, which provide the basis for studying the genetic effects of this trait and breeding vegetables with high glucosinolate retention during food processing. Non-enzymatic glucosinolate degradation, induced by heat, was studied in a publicly available Brassica oleracea doubled haploid population. Data were modeled to obtain degradation rate constants that were used as phenotypic traits to perform quantitative trait loci (QTL) mapping. Glucosinolate degradation rate constants were determined for five aliphatic and two indolic glucosinolates. Degradation rates were independent of the initial glucosinolate concentration. Two QTL were identified for the degradation rate of the indolic glucobrassicin and one QTL for the degradation of the aliphatic glucoraphanin, which co-localized with one of the QTL for glucobrassicin. Factors within the plant matrix might influence the degradation of different glucosinolates in different genotypes. In addition to genotypic effects, we demonstrated that growing conditions influenced glucosinolate degradation as well. The study identified QTL for glucosinolate degradation, giving the opportunity to breed vegetables with a high retention of glucosinolates during food processing, although the underlying mechanisms remain unknown.