Quantitative Trait Loci (QTL) Analysis of Carotenoid Content in Citrus Fruit

To obtain genetic information on carotenoid content in Citrus fruit for a breeding program, we investigated quantitative trait loci (QTL) in a mapping population derived from a cross between ‘Okitsu-46’ and ‘Nou-5’. Among individual progeny, total and each carotenoid contents were segregated in a transgressive manner. QTLs for total and each carotenoid contents were detected by Kruskal-Wallis analysis (P<0.01) and interval mapping (LOD (logarithm (base 10) of odds)>2.0) from 51 individuals. Most of the QTLs for each carotenoid component were mapped to different locations on the linkage map. In β-cryptoxanthin, the strongest QTL (LOD 3.4) was detected on linkage group 6 of ‘Nou-5’, and accounted for 26.9% of explainable variance. LOD scores of QTLs for total carotenoid content were lower than those for each carotenoid content. There were one QTL for total carotenoid content at the criteria of LOD>2.0, and seven weaker QTLs, which overlapped with QTLs for each carotenoid component. The effects of QTLs detected for each carotenoid content worked cumulatively to increase total carotenoid content. This study provides preliminary data because we obtained data in only one season and from a limited number of individuals (n=51). However, the results suggested that QTL information could be used to generate DNA markers to select progeny with higher carotenoid content.