A Joint Segregation Analysis of the Inheritance of Fertility Restoration for Cytoplasmic Male Sterility in Pepper

A cytoplasmic male sterility (CMS) system is one of the most efficient ways to produce F1 hybrid seeds in pepper (Capsicum annuum). Restorer-of-fertility (Rf) genes are a critical component within the CMS/Rf system. The inheritance of Rf genes in pepper by joint segregation analysis was examined. The inheritance of Rf genes in the two progenies was controlled by two major additive-dominant epistatic genes and additive-dominant epistasis polygene. The two major genes had high additive effects and dominant effects. In addition, there existed significant epistatic effects between the two major genes. The major genes had high heritability in F2, BC1, and BC2 generations. Also, the fertility restorer characteristic can be selected during early generations of the breeding cycle.

Genetic analysis of chlorophyll content in maize by mixed major and polygene models

Chlorophyll is an important factor which also affects the yield in maize. In this study, genetic analysis of chlorophyll content was conducted by joint segregation analysis of four generations P1, P2, F1 and F2:4 from the cross Shen3336?Shen3265 using the mixed major genes and polygenes inheritance models. Genetics of chlorophyll revealed that chlorophyll ?a? was controlled by two main gene having additive-dominanceepistasis effects. The heritability of these genes were 56.3%. Chlorophyll ?b? was controlled by two pairs of codominant major gene plus additive-dominance polygene. The heritability of these major genes and polygenes were 1.12% and 93.26% respectively. Chlorophyll ?a+b? was controlled by two pairs of additive-dominance- epistatic major genes plus additive-dominance polygene having heritability of 56.2% and 5.2% respectively.

The EIM algorithm in the joint segregation analysis of quantitative traits

In this article, a new algorithm for obtaining the maximum likelihood estimators (MLEs) of parameters in the joint segregation analysis (JSA) of multiple generations of P1, F1, P2, F2 and F2[ratio ]3 (MG5) for quantitative traits was set up. Firstly, owing to the fact that the component variance of the heterogeneous genotype in F2[ratio ]3 included both the first-order genetic parameters (denoted by the means of distributions) and the second-order parameters, a simple closed form for the MLEs of the means of component distributions did not exist while the expectation and maximization (EM) algorithm was used. To simplify the estimation of parameters, the first partial derivative of the above variance on the mean in the sample log-likelihood function was omitted. However, this would be remedied by the iterated method. Then, variances of component distributions for segregating populations were partitioned into major-gene, polygenic and environmental variances so that the generally iterated formulae for estimating the means as well as polygenic and environmental variances of component distributions in the maximization step (M-step) of the EM algorithm were obtained. Therefore, the EM algorithm for estimating parameters in the JSA model for the MG5 was simplified. This is called the expectation and iterated maximization (EIM) algorithm. Finally, an example of the inheritance of the resistance of soybean to beanfly showed that the results of mixed inheritance analysis in this paper coincided with those in both Wang & Gai (2001) and Wei et al. (1989), so the EIM algorithm was appropriate.