QTL形态标记定位的一种数学方法

A Mathematical Method for Mapping of QTL Using Two Morphomarkers

根据家蚕中位于Z染色体上的伴性遗传的双形态标记和假定与其有连锁关系的一个具有一对主基因差异的数量性状在测交世代中，所作的理论分布，本文建立了QTL形态标记定位的数学方法，即频数分布面积法，并给出了相应的检测一对主基因在测交世代中的同分离比例及其与形态标记是否有连锁关系的X2统计量．这种定位方法亦适应于非伴性遗传方式的QTL形态标记定位．与单标记定位的极大似然方法相比，我们的方法所作的双标记定位能显示QTL与形态标记发生重组的交叉干步作用，并且定位结果不受作用于数量性状的环境效应所影响．

Expectant distribution patterns of a quantitative trait that is assumed to be controlled by a major gene linking two sex-linked inheritable morphomarker genotypes in testcross generation in silkworm were given. From these expectant distribution patterns,we established a mathematical method for mapping of QTL using two sex-linked inheritable morphomarkers,i.e., distribution area of frequencies,which may be also used to map those QTLs being no sex-linked inheritable. With comparision of maximun likehood method for the mapping QTL using single marker, the result of QTL mapped by using our method can reveal the chiasma interference among QTL and Two morphomarkers, and does not be affected by environmental factors acting the quantitative trait controlled by QTL. On the other hand, we also established X2 statistic measures for 1: 1 segregational ratio of a pair major genes in testcross generation and for linkage relationship between them and morphomarkers.