Unraveling the Metabolic Basis of Quality Divergence in White and Yellow Qamgur (Brassica rapa L.) During Growth Through Comparative Metabolomics

Qamgur is a widely consumed vegetable and is also used in traditional medicine because of its extensive health benefits. White and yellow are the two main varieties. However, the mechanisms underlying quality development in these varieties, particularly in yellow Qamgur, remain unclear. This study compared nutritional and functional components throughout development. Total phenols and total isothiocyanates showed similar trends and levels in both varieties, whereas total free amino acids showed related but distinct patterns. Yellow Qamgur accumulated significantly higher levels of carotenoids. The integrated use of widely targeted and targeted metabolomics revealed stage-specific metabolites. White Qamgur showed stronger enrichment in secondary metabolite pathways, such as anthocyanin, flavonoid, steroid, terpenoid, and phenylpropanoid biosynthesis. In contrast, yellow Qamgur showed stronger enrichment in primary metabolic pathways, including amino acid biosynthesis. In addition, carotenoid biosynthesis may be the primary pathway responsible for the yellow coloration. Carotenoid profiling revealed that lycopene (28.94 mg/kg) was the predominant carotenoid in yellow Qamgur, followed by violaxanthin, γ-carotene, phytoene, β-cryptoxanthin laurate, and β-carotene.