Uncovering the genetic basis of carotenoid variations in maize kernels using two segregating populations

Abstract

Carotenoids, which serve as precursors of vitamin A and antioxidants, play important roles in human health. Breeding to increase carotenoid levels in cereal grains is an economically feasible way to address nutritional deficiency. Here, we performed quantitative trait–locus (QTL) mapping of 5 primary and 12 derived carotenoid-related traits in maize kernels in two segregating populations: Dan340 × K22 (KD) and K22 × CI7 (KC) F2:3/F2:4. In total, 185 putative QTLs in 32 genomic regions were identified for 17 carotenoid-related traits. For each trait, the number of QTLs per population ranged from 2 to 10, with a maximum of 4 QTLs explaining over 15% of the phenotypic variation. These findings suggest that a simple genetic basis underlies the variations in carotenoid-related traits in biparental populations. Moreover, additive effects mainly contribute to the genetic basis of these variations. We constructed a trait–locus network based on locus–locus linkage and locus–trait association information to explain the genetic basis of correlations among carotenoids and identified eight major common loci that control at least five traits. Overall, these findings enrich our understanding of the genetic basis of carotenoid accumulation in maize kernels, laying the foundation for improving multiple carotenoid traits by pyramiding desirable QTLs.