SLAF-Based Construction of a High-Density Genetic Map and Its Application in QTL Mapping of Carotenoids Content in Citrus Fruit

Carotenoids are important antioxidant components in the human diet. To develop carotenoid-rich agricultural products by genetic intervention, understanding the genetic basis of carotenoids variation is essential. In this study, we constructed a high-density integrated genetic map with 3817 molecular markers using specific locus amplified fragment (SLAF) sequencing from a C. reticulata × P. trifoliata F₁ pseudotestcross population. A total of 17 significant quantitative trait loci (QTLs) distributed on Chromosomes (Chr) 2, 3, 5, 6, and 9 were detected to determine the carotenoid variation in the population. In particular, three QTL colocalizations for multiple carotenoid constituents were observed on Chr 2, 3, and 9, one of which was located on Chr2:34,654,608-35430715 accounted for 20.1-25.4% of the variation of luteoxanthin, auroxanthin, lutein, violaxanthin, and total carotenoid content. Overall, this study provides a genetic foundation for marker-assisted selection (MAS) breeding of nutritionally enhanced citrus fruit.