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应用极大似然法分析质量—数量性状的遗传。假定分离世代中的同一主基因基因型因多基因和环境的变异而呈正态分布,不同主基因基因型则为具不同平均数和相同方差的混合正态分布。提出以EM算法对主基因的分离比率、基因效应、微基因的遗传方差等进行极大似然估计以及以似然比方法测验有关遗传假设的程序。以大麦一个杂交组合的F_2代株高资料为例演示了分析过程。结果表明该组合的株高遗传涉及一个主基因和一组微基因;主基因杂合体为完全显性,显性效应达 14.97cm;微基因的遗传方差为65.14cm~2;环境方差为 14.80cm~2。本文的原理和方法可以推广于多个分离世代的联合分析以及利用分子标记构建数量性状基因图谱等。
Applying Maximum Likelihood Method to Analyze the Inheritance of Quality - Quantitative Traits. It is assumed that the genotypes of the same major gene in the isolated generation are normally distributed due to the variation of multiple genes and environments, while the genotypes of different major genes are mixed normal distributions with different mean and same variance. The EM algorithm was proposed to evaluate the maximum likelihood ratio of major genes, gene effect, genetic variance of microgenes and so on, and to test the genetic hypotheses by the likelihood ratio method. The F2 plant height data of a cross combination of barley was taken as an example to illustrate the analysis process. The results showed that the heredity of the combinations involved a major gene and a group of mini-genes. The major gene heterozygosity was completely dominant with a dominant effect of 14.97 cm. The genetic variance of the microgenes was 65.14 cm -2. The environmental variance was 14.80 cm ~ 2. The principle and method of this article can be extended to the joint analysis of multiple isolated generations and the use of molecular markers to construct quantitative trait gene maps.