Genetic Study On Fruit Shape, Color And Calyx Color Traits In Eggplant (Solanum Melongena L.)

Eggplant (Solarium melongena L.) is an annual herb vegetable crop in Solatium, Solanaceae. It is one of the most important vegetables widely consummated in China. Knowledge of the heredity of fruit characteristics is the foundation of eggplant breeding, and is practically necessary to genetic linkage analysis, gene mapping, and isolating, cloning and usage of target genes. In the present study, we chose four selfed eggplant lines as parents, which are different in fruit shape, fruit color and calyx color, and applied diallel cross and a joint analysis of P₁, P₂, F₁, B₁, B₂ and F₂ generations, to analyze the traits of fruit shape, fruit color and calyx color.1. Heredity of fruit shape. Eggplant fruit-shape was a quantitative traits controlled by a number of genes. The optimal model was the E-1 model, that is, two additive-dominance-epitasis major gene plus additive-dominance polygene mixed inheritance model. The offspring of different fruit shape combinations expressed more phenotype of low-value parents. The obvious tendency to parents can be used in matching designs in crosses. The analysis of genetic effects indicated that the index trait of fruit color in eggplant was dominated by additive effect, and was inherited steadily. That can be used with pedigree method in breeding. There were high broad-sense and narrow-sense heritability of the index trait of eggplant fruit shape, which were less affected by environmental factors. A positive effect was obtained when selection was made in early generations according to the phenotype, and the index trait of eggplant fruit shape was stably inherited to the following generations.2. Heredity of fruit color. Eggplant fruit color was quantitative trait and controlled by polygene, whereas a high major gene effect was observed. The results of three crosses indicated that the inheritance of fruit color fitted the E Model, that is, the additive-dominance-epitasis major gene plus additive-dominance-epitasis polygene. The analysis of genetic effects indicated that inheritance of fruit color traits was dominated by additive effect, but the dominance effects also could not be ignored. The broad-sense heritability of the eggplant fruit color traits is very high whereas the narrow-sense heritability is lower. For fruit color, thus, heterosis should be exploited in breeding.3. Heredity of fruit calyx color. Eggplant fruit calyx color traits follow nuclear inheritance. The purple calyx is dominant to green calyx. In the backcross B₁ generation, green calyx and purple calyx appeared in a ratio of almost 1 to 1. In their F₂ generation, fruit calyx color divided into three color populations: green-purple, green and purple, and the ratio fitted 9 to 3 to 4 by X² test, indicating that fruit calyx color trait is control by two pairs of genes, and there existed a gene interaction, i.e., recessive epistatic effect.