Genetic Analysis of Silique Length Using Mixture Model of Major Gene Plus Polygene in Brassica napus L.

Abstract

Silique is one of major components for rapeseed yield. Inheritance of silique body length(SBL), valid silique length(VSL) and beak length(BL) in a cross of variety Zhongshuang 11 with long silique(P1) and line 10D130 with short silique(P2) was investigated by the mixed major gene plus polygene inheritance model. The results showed that SBL, VSL and BL in the populations of F2, BCP1, and BCP2 were controlled by the major gene and polygenes. The SBL were dominated by two major genes with additive-dominance-epistasis effects plus polygenes with additive-dominance-epistasis effects(E-0 model). The heritability values of the major genes of SBL in BCP1, BCP2, and F2 were estimated as 51.10%, 74.23%, and 66.93%, respectively, and the heritability values of the polygene were 29.16%, 17.11%, and 23.96%, respectively. The additive effects of two major genes of SBL were 1.75 and –0.06, and the dominant effects of two major genes were –0.59 and –0.86, respectively. The valid silique length was controlled by two major genes with additive-dominance-epistasis effects plus polygenes with additive-dominance effects(E-1 model). Heritability values of the major genes for SL in BCP1, BCP2, and F2 generations were estimated as 47.63%, 68.51%, and 79.45%, respectively, and the heritability values of the polygene were 29.40%, 20.89%, and 12.47%, respectively. The additive effects of two major genes were equal(0.34) to that of the cross, but the dominant effects of the two major genes were –0.81 and –0.47, respectively. The beak length was dominated by two major gene with additive effects plus polygenes with additive-dominance effects(E-3 model). Heritability values of the major genes of BL in the cross were 33.71%, 72.75%, and 52.25%, respectively, and the heritability values of the polygene were 40.08%, 5.37%, and 27.60%, respectively. The additive effects of two major genes were 0.20 and –0.20, respectively.