| Trait introgression from Brassica juncea to B. rapa was studied in an attempt to develop yellow-seeded, self-compatible B. rapa biotypes with acceptable oil and protein content, fatty acid profiles, and disease resistance. Microspore culture of B. juncea/B. rapa interspecific lines was unsuccessful in producing high frequencies of haploid embryos. An unbalanced genome or absence of a genotype-specific embryogenesis trait may have contributed to this failure. Molecular marker analysis verified the introgression of DNA from B. juncea to B. rapa, while cytological examination revealed the regular formation of 10 bivalent chromosome associations during meiosis. The interspecific lines had moderate to high levels of resistance to Leptosphaeria maculans , were susceptible to race 7v of Albugo candida, and segregated for resistance to race 2a of A. candida. Genetic variation in the BC2F3 B. juncea/B. rapa interspecific lines would allow selection for increased oil and protein content, a more nutritionally balanced fatty acid profile, and reduced days-to-maturity. |
