Genetic Variation in Carotenoid Concentrations among Diploid and Amphidiploid Rapid-cycling Brassica Species

Vegetable crops can be significant sources of nutritionally important dietary carotenoids, and Brassica are sources that also exhibit antioxidant and anticarcinogenic activity. The family Brassicaceae contains a diverse group of plant species commercially important in many parts of the world. The six economically important Brassica species are closely related genetically. Three diploid species (B. nigra, B. rapa, B. oleracea) are the natural progenitors of the amphidiploid species (B. juncea, B. napus, B. carinata). The objective of this study was to characterize the accumulation of important dietary carotenoid pigments among the genetically related Brassica species. High-performance liquid chromatographic quantification revealed significant differences in carotenoid and chlorophyll pigment concentrations among the Brassica species. Brassica rapa accumulated the highest concentrations of antheraxanthin [0.79 mg/100 g fresh weight (FW)], lutein (8.89 mg/100 g FW), and zeaxanthin (0.75 mg/100 g FW). The highest concentrations of ß-carotene (4.41 mg/100 g FW) and total chlorophyll (125.9 mg/100 g FW) were found in B. juncea. Brassica nigra accumulated the highest concentrations of 5,6-epoxylutein (0.41 mg/100 g FW) and violaxanthin (2.28 mg/100 g FW), whereas B. oleracea accumulated the highest concentrations of neoxanthin (2.10 mg/100 g FW). For many of the pigments analyzed, the amphidiploids B. carinata and B. napus accumulated significantly less carotenoid concentrations than the diploid species and B. juneca. Brassica convey unique health attributes when consumed in the diet. Identification of genetic relationships among the Brassica species would be beneficial information for improvement programs designed to increase carotenoid values.