Glucosinolate variation, heterosis, and prediction of hybrid performance from parental values in white cabbage (Brassica oleracea var. capitata)

Glucosinolates (GSLs) are sulfur-containing secondary metabolites with important roles in plant defense and human health. Developing hybrids with increased GSL content is a promising approach to improve both resistance and health-related traits in cabbage. In other crops, moderately to highly heritable traits often show strong parent–hybrid correlations, enabling prediction of hybrid performance from parental phenotypes. Because GSLs show moderate to high heritability in closely related Brassica crops, this strategy has strong potential for developing cabbage hybrids with increased GSL content. Here, we evaluated GSL composition, variation, heterosis, and parent–hybrid correlations in 14 cabbage (Brassica oleracea var. capitata) doubled haploid lines, 11 derived hybrids, and two commercial hybrids. Desulfoglucosinolates were quantified by UHPLC–MS/MS using glucotropaeolin as an internal standard. Thirteen GSLs were detected across all genotypes, and total GSL concentrations ranged from 19.7 to 67.8 μmol g⁻¹ dw, indicating substantial genotype-dependent variation, with aliphatic GSLs dominating the profile (73.0%), followed by indolyl (26.9%) and aromatic (0.1%). Hierarchical clustering revealed two major genotype groups, differentiated primarily by 3C and 4C aliphatic GSLs, with correlation analysis reflecting coordinated regulation and trade-offs in their accumulation. Mid-parent heterosis (MPH) varied by compound and parental combination, with some GSLs showing consistently positive MPH (e.g., gluconapin) and others consistently negative MPH (e.g., neoglucobrassicin). Linear regression models showed that mid-parent values explained a high proportion of hybrid variability for major aliphatic glucosinolates and, to a lesser extent, for indolyl glucobrassicin, supporting the use of parental phenotyping to predict hybrid GSL performance. In parallel, agronomic traits showed uniformly positive mid-parent heterosis, with head weight exhibiting the highest values. Overall, these results support integrating parental GSL profiling into cabbage breeding to improve nutritional and defense-related traits alongside yield, thereby reducing the need for extensive testcrossing and field trials.