Development of high-oleic, low-linolenic acid Ethiopian-mustard (Brassica carinata) germplasm

Seed oil of current zero erucic-acid germplasm of Ethiopian mustard ( Brassica carinata A. Braun) is characterized by a low concentration of oleic acid and high concentrations of linoleic and linolenic acids. Sources of increased oleic-acid (HO) and reduced linolenic-acid (LL) concentration have been developed separately in high erucic-acid germplasm. The objectives of the present research were to study the inheritance of the HO and LL traits in crosses HO x LL, and to develop HOLL recombinants, both in high erucic-acid and zero erucic-acid backgrounds. The HO mutant N2-3591 (about 20% oleic acid compared to 9% in conventional high erucic-acid materials), was reciprocally crossed with the LL lines N2-4961 and HF-186 (both with about 5% linolenic acid compared to 12% in standard high erucic-acid materials). Increased oleic acid concentration of N2-3591 was found to be controlled by alleles at one locus (Ol), whereas three different loci for reduced linolenic-acid concentration (Ln, Ln1 and Ln2) were identified in N2-4961 and HF-186. Crosses between N2-3591 and N2-4961 generated HOLL recombinants where levels of increased oleic-acid and reduced linolenic-acid were similar to those of the parents. However, a transgressive segregation for oleic acid was observed in crosses between N2-3591 and HF-186, where F(2) seeds with up to 29.7% oleic acid were obtained, in comparison to an upper limit of 25.1% in the N2-3591 parent grown in the same environment. The transgressive increased oleic-acid was expressed in the F(3) generation and was attributed to the presence of a second locus, designated Ol2. The transgressive trait was transferred to the zero erucic-acid line 25X-1, resulting in a zero erucic-acid germplasm with very high oleic-acid concentration (83.9% compared to 32.9% in 25X-1) and low linolenic-acid concentration (5.0% compared to 16% in 25X-1). Additionally, two other lines exhibiting different stable levels of increased oleic-acid (70.7% and 79.5%, respectively) and reduced levels of linolenic-acid (7.5% and 8.7%, respectively) were isolated.