[QTL mapping for contents of main carotenes and lycopene in carrot (Daucus carota L.)].

An F2 population derived from two carrot inbred lines, P50006 and HCM A.C. with high carotene accumulation, was developed and used to map and analyze quantitative trait locus (QTL) associated with the accumulation of alpha and beta-carotene, total carotene and lycopene. Broad-sense heritabilities of these traits were 0.75, 0.50, 0.31, and 0.93, respectively. A genetic map with 91 SRAP (Sequence-related amplified polymorphism) markers was developed, which spanned 502.9 cM in 9 linkage groups with a mean marker interval of 5.5 cM. Mixed-model-based composite interval mapping was performed to analyze QTL and epistasis effects. One major QTL each for beta-carotene, total carotene and lycopene accumulation were detected which can explain 12.79%, 12.87%, and 14.61% of total phenotypic variations, respectively. Additive genetic variance was primarily responsible for genetic variability in all three major QTL. In addition, a pair of epistasis QTL for beta-carotene and lycopene accumulation was detected, which were able to explain 15.1% and 6.5% of total phenotypic variation, respectively. The dominant x additive and dominant x dominant interaction variance were primary epistasis effect for beta-carotene and lycopene. These SRAP markers linked to QTL could be used in selection or QTL pyramiding for high carotene and lycopene content in carrot breeding.