Chromosome elimination and fragment introgression and recombination producing intertribal partial hybrids from Brassica napus x Lesquerella fendleri crosses

The intertribal sexual hybrids between three Brassica napus (2n = 38) cultivars and Lesquerella fendleri (2n = 12) with the latter as pollen parent were obtained and characterized for their phenotypes and chromosomal and genomic constitutions. F-1 plants and their progenies mainly resembled female B. napus parents, while certain characters of L. fendleri were expressed in some plants, such as longer flowering period, basal clustering stems and particularly the glutinous layer on seed coats related to drought tolerance. Twenty-seven F-1 plants were cytologically classified into five types: type I (16 plants) had 2n = 38, type II (2) had 2n = 38-42, type III (3) had 2n = 31-38, type IV (5) had 2n = 25-31, and type V (1) had 2n = 19-22. Some hybrids and their progenies were mixoploids in nature with only 1-2 chromosomes or some chromosomal fragments of L. fendleri included in their cells. AFLP (Amplified fragments length polymorphism) analysis revealed that bands absent in B. napus, novel for two parents and specific for L. fendleri appeared in all F-1 plants and their progenies. Some progenies had the modified fatty acid profiles with higher levels of linoleic, linolenic, eicosanoic and erucic acids than those of B. napus parents. The occurrence of these partial hybrids with phenotypes, genomic and fatty acid alterations resulted possibly from the chromosome elimination and doubling accompanied by the introgression of alien DNA segments and genomic reorganization. The progenies with some useful traits from L. fendleri should be new and valuable resource for rapeseed breeding.