主基因-多基因混合模型下种畜标记辅助遗传评定的效率

Accuracy of Marker Assisted Genetic Evaluationunder the Major Gene-Polygene Mixed Inheritance Models

在主基因-多基因混合遗传模型的框架内模拟研究了种畜遗传评定的相对效率,比较了常规BLUP与标记辅助BLUP(MBLUP)进行个体遗传评定的效果,模型中将与标记紧密连锁的QTL效应看作随机效应,分子标记的间距为5cM,QTL的基因型通过侧翼标记来推断。试验设计为半同胞女儿设计,模拟中还考虑了性状遗传力和QTL效应的不同水平对MBLUP评定效果的影响。研究结果表明,多数情况下,MBLUP较常规BLUP具有更大的相对优势,二者的遗传评定效果均直接受性状遗传力和QTL效应的影响,随着性状遗传力的提高,两种方法遗传评定的准确性也进一步提高,但MBLUP的相对优势不断下降;而随着QTL效应的增加,MBLUP的相对优势则有不断增大的趋势。特别是在高QTL效应和低遗传力的情况下标记辅助BLUP的优势最为明显,个体遗传评定的相对准确性增加幅度也最大。

Methodology of individual genetic evaluation by using marker assisted BLUP (MBLUP) based on the framework of a mixed inheritance model was present in the paper. The effects of putative QTL were treated as random effect in the major gene and polygene mixed inheritance model,and its genotypes were inferred from the flanking markers with 5 cM map distance between them.The efficiency of genetic evaluation was compared with the traditional BLUP.The factors of influencing MBLUP efficiency (e.g. QTL effect and heritability) were simulated too. Daughter design with multiple families was applied, and the number of segregating population is 500. The results showed that MBLUP have a certain advantage for individual genetic evaluation in many cases. The accuracy of genetic evaluation depended on the effect of putative QTL and the value of heritability. With the increase of heritability, the accuracy of genetic evaluation improved slightly, but the relative advantage of the MBULP decreased correspondingly. However, with the increase of QTL effect, the relative advantage of the MBLUP improved correspondingly, especially in the case with low heritability and high QTL effect.