The Study On The Correlation Method For Mapping Quantitative Trait Loci Using Flanking Markers In Three-points Backcross

QTL is the abbreviation of Quantitative Trait Loci and the region on the chromosome which influences Quantitative Trait. The procedures for finding and locating QTLs are called QTL mapping. The finding of a single gene is very important. First, it can improve the efficiency of breeding select, especially, it takes a great effect on the low heredity trait; secondly, transfer gene technique can be used on quantitative trait; thirdly, it also can distinguish the genetic disease caused by many factors and provide basis for gene therapy and preventive method; finally, it can help to deepen the understanding of evolution after we get the number and the trait of gene. Three-points backcross is the classical method in genetic linkage mapping, and is applied in genetic mapping widely. However, most methods at that time ignore cross interference. First, the paper has studied the three-points backcross colony with the method of maximum likelihood estimation, has explained the mapping functions and has estimated the recombination value and it standard error. It makes up for the weakness of the classical calculating method, and makes the linkage mapping of genes more accurate. Then the paper has studied the correlation method for mapping quantitative trait loci using flanking markers in three-points backcross with cross-interference and has estimated the recombination value and it standard error between quantitative trait loci(QTL) and marker loci(ML). The examples indicate the practical sense of the formulas.