Fatty Acid Inheritance in Wide Reciprocal Oilseed Crosses ( Brassica rapa and B. napus )

Erucic acid content and inheritance were studied in Brassica alboglabra, B. rapa and resynthesized B. napus from these parental species. Although significant variation in erucic acid content was found between the 20 B. alboglabra lines, all of them had to be classified as high erucic types. No major erucic acid gene polymorphism was identified. In B. rapa the erucic acid content was regulated by one major gene, which showed partial dominance in three of the four crosses analysed. The high erucic gene seemed to function more efficiently in the Yellow Sarson cytoplasm, resulting in maternal differences when reciprocal crosses were compared. In crosses where modern low erucic acid lines were used as female parents the zero erucic acid F2-individuals occurred more frequently than expected. Segregation of the erucic acid content in crosses involving resynthesized B. napus showed a good fit to a two locus model. No maternal effects were found, but deviations from mid-parent values in the high erucic acid direction occurred in most of the F1-hybrids, indicating partial dominance. Crosses between resynthesized oilseed rape and natural oilseed rape resulted in oleic acid transgressive F5-lines.