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 F-2 and BC1 generations from two zero x 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 'CCWF16' 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 halfseed 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 ( E 2) associated with the A genome had a greater contribution to the total erucic acid content in B. juncea than the gene ( E 1) located on the B genome. This provided experimental evidence for a previous suggestion of unequal contributions of two dominant genes (E-1 = 12%, E-2 = 20%) to high erucic acid content in conventional digenomic Brassica species.