Abstract
We present a maximum likelihood method based on composite interval mapping (CIM) for analyzing QTL in a mixed population composed of different F2 populations derived from diallel cross among several pure lines. A statistical model for mapping QTL and estimating QTL parameters was discussed and a maximum likelihood procedure based on the model was explained. Using simulated data, the power of QTL detection and the effciency in estimation of QTL parameters with the CIM-based method in diallel cross were evaluated in comparison with a method based on simple interval mapping (SIM). It was shown that two linked QTLs can be resolved more effectively by CIM than SIM. Even in the case of existence of multiple QTLs, unbiased estimates of a position and effects for each QTL were obtained by CIM, while SIM gave much biased estimates in such a case. In conclusion, the CIM-based method is useful in QTL analysis with diallel designs.
