[Major gene plus poly-gene inheritance of erucic acid content in Brassica napus L]

Inheritance of erucic acid content in the cross of HSTC14 x Ningyou 7 (Brassica napus L.) was investigated by applying the major gene plus poly-gene model of quantitative traits to a joint analysis of multi-generations (P1, F1, P2, B1:2 B2:2 and F2:3). The results showed that erucic acid content in the cross of HSTC14 x Ningyou 7 was controlled by two major genes with additive-dominance-epistatic effects plus polygenes with additive-dominance effects (the E-1 model). Heritability values of the major genes of B1:2, B2:2 and F2:3 population were estimated as 69.47%, 28.25% and 51.33% respectively, while those of polygene were 29.81%, 70.39% and 47.86%. This results demonstrated that erucic acid content level in the cross was mainly controlled by two major genes mixed with the effect of polygenes. The estimated additive effects of the two major genes, da and db, were -12.1712 and -6.5423 respectively. The dominant effect of the first major gene was 9.1011, much higher than that of the second one. The interaction effect of the first major gene's additive effect and the second major gene's dominance effect was 22.4400, while that between the second major gene's additive effect and the first major gene's dominance effect was only 1.0317. There were obvious differences in genetic effects between the two major genes. The effect of db was only about 53.75% that of da, indicating that the contributions to erucic acid level of the two major genes was not equal in the cross. The possible reasons resulting in the difference was discussed in this paper.