Maternal doubled haploid production in interploidy hybridization between Brassica napus and Brassica allooctaploids

We found a new in vivo route to produce maternal doubled haploid of Brassica napus . The pollen donor, an allooctaploid rapeseed, acts as a DH inducer. Inbred line has a powerful advantage in cultivar breeding and genetic analysis. Compared to the traditional breeding methods, doubled haploid production can save years off the breeding process. Though genotype-dependent tissue culture methods are widely used in the Brassica crops, seed-based in vivo doubled haploid developing systems are rare in nature and in the laboratory. As interspecific cross and interploid hybridization play an important role in genome evolution and plant speciation, we created a new Brassica artificial hybrid, a Brassica allooctaploid (AAAACCCC, 2n = 8x = 76), by interspecific crossing and genome doubling. A homozygous line was observed at the third self-generation of a synthesized Brassica allohexaploid (AAAACC, 2n = 6x = 58). Crosses between B. napus as female and Brassica allooctaploid as pollen donor were conducted, which yielded maternal doubled haploid B. napus that were identified based on phenotype, ploidy, and molecular analysis. The Brassica octaploid acted as a maternal doubled haploid inducer and had a relatively high induction rate. Our research provides a new insight for generation of homozygous lines in vivo using a single-step approach, as well as promotes the understanding in breeding programs and genetic studies involving the Brassicas.