Erucic acid heredity in Brassica juncea - some additional information

Genetic studies were undertaken to reassess erucic acid heredity in Brassica juncea. Analysis of segregation in F₂ and BC₁ generations from two zero × high erucic acid crosses indicated that higher erucic acid in B. juncea was controlled by two dominant genes with additive effects, whereas segregation in a cross involving ‘CCWF 16′, a genotype having intermediate erucic acid (25.6%), and a zero erucic acid strain, indicated monogenic dominant control for intermediate erucic acid content. The B. juncea strain ‘CCWF 16’ was developed by hybridizing high‐erucic acid B. juncea cv.‘WF‐1’ with a ‘0’ erucic B. rapa cv.‘Candle’ followed by backcrossing with ‘WF‐1’ and half‐seed selection for low erucic acid in each backcross generation. This strategy resulted in substitution of the high erucic acid allele present in the A genome of B. juncea (AABB) by the zero erucic acid allele associated with ‘A’ genome of ‘Candle’. The intermediate erucic acid content in ‘CCWF 16’ was thus attributed to a gene present in the ‘BB’ genome. Experimental data clearly suggested that the gene (E₂) associated with the A genome had a greater contribution to the total erucic acid content in B. juncea than the gene (E₁) located on the B genome. This provided experimental evidence for a previous suggestion of unequal contributions of two dominant genes (E₁= 12%, E₂= 20%) to high erucic acid content in conventional digenomic Brassica species.