Use of additive-dominant model in genetic analysis of some quantitative caracteristics in sunflower

Abstract

A simple link between the expected means of quantitative traits of different generations (progenies) can be established if the mean values are dependant exclusively on additive and dominant gene effects. Th is study aims to prove the correctness of the hypothesis that progeny means depend solely on additive and dominant genes, which can be tested in several ways, one of which is the applied tests. Seven F1 hybrids obtained by crossing five sunflower inbred lines were used to analyze the impact of genes with additive and dominant effects and their interactions on the inheritance of plant height, leaf number per plant and head diameter. Th e linkage among the expected progeny means was tested using the scaling tests method, while the estimates of gene effects and mode of inheritance were made by Generation Mean Analysis. The additive-dominant model proved adequate only for leaf number per plant in crosses C5 and C7. Besides the main gene effects (additive and dominant), epistatic gene effects were also of great importance in the inheritance of all three traits. In the inheritance of plant height, duplicate epistasis between dominant increasers was found in C2 , while C1, C4 and C7 had duplicate epistasis between dominant decreasers. In the case of leaf number per plant, we only found duplicate epistasis between dominant decreasers in C1, C3 and C6, while in the inheritance of head diameter both types of duplicate epistasis were found, namely duplicate epistasis between dominant decreasers in C1 and duplicate epistasis between dominant increasers in C2. It can be concluded that the additive-dominance model was not adequate in explaining the differences between various generation means. In addition to of additive and dominance gene effect, digenic epistatic effects were also found to be important in the inheritance of the characters studied. Therefore, geneticists and breeders working on sunflower should make provisions for the occurrence of epistatic gene effects in their research programs.