Abstract:

【Objective】 White flower color in Brassica napus L. was observed quantitatively and the genetic characteristics were analyzed in order to provide a theoretical basis for its applications in rapeseed breeding. 【Method】 Six generations (P1, P2, F1, B1, B2 and F2) of two crosses (HW243×HZ21-1, HW243×Zhongyou 821) were used as genetic populations and fresh petals were taken and scanned with a computer scanner. The characteristic values（CIE RGB system）of petal color were obtained with a self-designed computer software. The genetic characteristics of the white flower color were analyzed with a mixed model of major genes plus polygenes. 【Result】 It was found that the white flower color in Brassica napus L. appeared to be a quantitative trait and its inheritance fitted to a mixed genetic model of two major genes with additive-dominant-epistatic effects plus polygenes with additive-dominant-epistatic effects (the E-0 model). The additive, dominant and epistatic effects of major genes were all important. Heritabilities of the major genes were estimated to be 96.94% and 95.83% in F2, 54.58% and 49.57% in B1, 98.14% and 97.67% in B2. Heritabilities of the polygenes were estimated to be 3.93% and 2.47% in F2, 35.64% and 46.9% in B1, 0.98% and 2.06% in B2. 【Conclusion】 The white flower color in B. napus L. appeared to be a quantitative trait. Its inheritance fitted to a genetic model of two major genes with additive, dominant and epistatic effects plus polygenes with additive, dominant and epistatic effects. The effects of major genes were dominant and the effects of polygenes were relatively small. Heritabilities of the major genes were high, and environmental influence was small.

Key words: Brassica napus L., white flower, CIE RGB characteristic value, major gene plus polygene, genetic model