In order to further study the functions of class Ⅲ peroxidase (PRX) family genes in Brassica rapa (BrPRX), the BrPRX was identified by genome-wide analysis, and its bioinformatics analysis was carried out. The results showed that there were a total of 121 BrPRX members, contained 0-9 introns, exhibited unequal distribution on chromosomes, and multiple pairs of BrPRX genes were distributed on chromosomes with tandem duplication. Phylogenetic analysis of PRX family genes from Arabidopsis thaliana and B. rapa suggested that these members could be divided into five groups. Synteny and K_a/K_s analyses demonstrated that B. rapa had a high homology with A. thaliana, and most of BrPRX family gene had undergone strong purifying selection in the evolution. The analysis of cis-acting regulatory elements of BrPRX family genes showed that they played important roles in hormone response regulation, light response and resistance to adversity. In addition, transcriptome data analysis showed that the BrPRX genes had tissue expression specificity, and some of them were down-regulated in the male sterility materials. These results lay a foundation for the further study of PRX genes’ function in B. rapa.

In order to examine the genetic background of Micropterus salmoides, eleven microsatellite loci were used to study the genetic diversity and structure of the introduced subspecies (California M. salmoides), selected subspecies from Taiwan Province (Taiwan-California M. salmoides) and cultured species (Youlu No. 1) in mainland. The results showed that both the number of alleles and effective alleles was higher in California M. salmoides than in Taiwan-California M. salmoides and Youlu No. 1. The observed heterozygosity and expected heterozygosity at five loci were significantly higher in California population than in Taiwan-California and Youlu No. 1 populations, which were similar. According to the polymorphic information content, eleven loci in the California population were at high polymorphic levels. Six loci and four loci were at highly polymorphic levels for Youlu No. 1 and Taiwan-California populations, respectively. In the genetic equilibrium test, it was found that there were more loci deviating from Hardy-Weinberg equilibrium in Taiwan-California population, and there were three linkage pairs in California population (P＜0.05). For the two-phased model of mutation (TPM), both WILCOXON and sign tests showed that California population was in a status of mutation-drift disequilibrium. For population structure, it was found by analysis of molecular variance (AMOVA) that 15.57% of the genetic variation came from among populations, 25.05% from within populations, and 59.38% from among individuals (P＜0.01). The genetic distance between California population and Youlu No. 1 population was the largest, followed by that between California population and Taiwan-California population. When the K was two, there were significant differences in genetic structures between California population and other two populations. Through individual population identification, California population had the lowest rate of misjudgment, followed by Youlu No. 1 and Taiwan-California populations. When the accuracy was 85.00%, the probabilities of correct discrimination of California, Youlu No. 1 and Taiwan-California populations were 67.70%, 53.30% and 20.00%, respectively. According to the analysis of genetic diversity, genetic distance and equilibrium test, it was found that the original species of California had high polymorphism, and the genetic distance was bigger than that of the other two populations, and there might be genetic bottleneck. It is suggested that the species of M. salmoides introduced from the United States should be expanded and cultivated systematically.

Sugar contents of six generation populations (P₁, P₂, F₁, F₂, B₁ and B₂) derived from the cross between low sugar content inbred line ‘Huapicaigua’ (Cucumis melo var. conmmon Makino) and high sugar content inbred line ‘XLH’ (Cucumis melo var. saccharinus Naud.) were determined by high performance liquid chromatography (HPLC) method. Fruit sugar related traits in melon were analyzed using the joint segregation analysis method of a mixed major gene plus polygene genetic model. The results showed that the genetic model E-0, incorporating two pairs of additive-dominance-epitasis major genes plus an additive-dominance-epitasis polygene, was the best-fitting genetic model for fruit fructose content; and the genetic model E-1, incorporating two pairs of additive-dominance-epistasis major genes plus an additive-dominant polygene, was the optimal genetic model for fruit glucose, sucrose and total sugar contents. The fructose, glucose, sucrose, and total sugar contents were all controlled by two pairs of major genes and polygenes; the additive effect of major genes was mainly negative, and the interaction between the major genes was in common. Among them, the dominant and dominant interaction effect of the major genes for fructose, glucose and total sugar contents were the strongest, while the dominant and additive interaction effect of the major genes for sucrose content was the strongest. The negative additive effect of polygenes for sucrose and total sugar contents was relatively obvious. The heritabilities of major genes in the F₂ populations conferring the fructose, glucose, sucrose and total sugar contents were 85.7%, 86.2%, 92.7% and 85.0%, respectively; and the environment showed very little effect for fruit sugar content. Thus, in melon breeding, selection for high sugar content in early generation melon is desirable.

Full model and multi-loci additive model were used to analyze the days to silk (DS, female flowering) of maize nested association mapping (NAM) population. Analysis with the full model revealed that small effects of additive, dominance, epistasis, and their environmental interactions of many loci controlled the DS of maize NAM population. Dominance related effects had large impacts on the trait. Estimated total heritability was 79.86%, whereas 50.52% was due to dominance related effects. Environmental specific genetic effects also revealed as imperative for DS, explained 27.31% phenotypic variations. The highly significant (-log10 PEW>5) quantitative trait SNPs (QTSs) identified were 50 for full model, but 47 for additive model with low heritability (31.65%). Utilizing the association analysis results of DS, genotypes and total genetic effects of superior lines, superior hybrids were predicted that could be useful for future breeding program.