Genetic Analysis Of Important Traits Using ADAA Model And Prediction Of Heterosis Using SNP Markers In Brassica Napus L.

Analysis of genetic effects and genetic correlations of important traits can provide theoreticalguidance for the genetic improvement of rapeseed. In the process of hybrid breeding, prediction ofheterosis using molecular markers, can greatly reduce the workload of the field test, and improvebreeding efficiency. Fourteen excellent parental lines (including6maintainer lines and8restorer lines）which bred in recent years were used to design a6×8partial diallel cross. Eleven important traits ofparental lines and their F1and F2populations were investigated, which included plant height (PH)、height of primary branch (HPB)、number of effective primary branch (NEPB)、silique density (SD)、effective length of main inflorescence (ELMI), effective siliques of main inflorescence (ESMI),effective siliques per plant (ESP), seeds per silique (SS), thousand-seed weight (TSW), yield per plant(YP) and pod shattering resistance index (SRI).The additive dominance with additive-by-additiveepistatic effects (ADAA) genetic model was used to analyze the genetic effects and correlations ofdifferent traits, and to explore the nature of genetic correlations among those important traits. At thesame time, the heteroses of yield-related traits were analyzed, and the genotypes of parental lines wereidentified using the rapeseed60K SNP chip. Genetic distances (GD) between parental lines werecalculated according to their genotypes. Then analysis of the relationship between GD and heterosis, inorder to explore the feasibility of heterosis prediction using SNP markers in rapeseed (Brassicanapus).The main results are summarized as follows:1. The inheritance of yield-related traits was mainly controlled by dominant effects, dominanceby environment interaction effects and additive-by-additive epistatic effects. Additive effects were alsooccurred in the inheritance of PH, ELMI, SS, and TSW. The dominant effects of all yield-related traitswere greater than their additive effects and epistatic effects, and the dominance by environmentinteraction was also obviously greater than the additive by environment interaction and the epistasis byenvironment interaction, indicating that heterosis plays an important role in improving the yield ofrapeseed.2. The inheritance of pod shatter resistance was in accord with the additive-dominance-epistaticgenetic model. The additive effect is biggest, followed by epistatic effect, the dominant effect isrelatively small, and their genetic variance component ratios were0.342,0.280and0.246respectively,indicating the little potential to improve rapeseed pod shatter resistance by heterosis utilization.3. PH, HPB, SD, ESMI and SS showed significant genetic correlation with YP, and the maincomponent of the genetic correlation was the dominance correlation; NEPB and ESP also showedsignificant genetic correlation with YP, and the main component of the genetic correlation was theadditive-by-additive epistatic correlation; implying that heteroses of these traits can be used to indirectlyimprove YP.4. Among ten yield-related traits in this study, YP had the highest mid-parent heterosis (MPH)and the highest high-parent heterosis (HPH). The MPH of YP ranged from,with the average of HPH of YP ranged between, and the average was Among all F1combinations,8908B×R6had the highest MPHand HPH on YP, indicating that it is a hybrid combination with high yield potential.5. The GD between maintainer lines and restorer lines, which calculated using40201SNPmarkers, ranged from0.3626to0.8811; the correlations between GD and heteroses (including MPH andHPH) of PH, HPB and YP were significant, and the correlations between GD and MPH were better thanGD and MPH. The correlation coefficients between GD and the MPH of those three traits weredetermination coefficients were indicating that the GD estimated by SNP markers can predict theheterosis of PH, HPB and YP in a certain extent.