Production and characterization of interspecific hybrids between tuber mustard (Brassica juncea) and red cabbage (Brassica oleracea) through embryo culture

There are abundant genetic types in Brassica species, containing six economically important Brassica species sharing three major genomes (A, B, and C), which are arranged in diploid (genome: AA, BB, and CC) and allotetraploid (genome: AABB, AACC, and BBCC) species. Interspecific hybridization between Brassica species is an important way to combine the valuable characters of different species. In the present study, interspecific hybrids between tuber mustard (AABB) and red cabbage (CC) were obtained with the aid of embryo culture techniques. The results showed that embryo culture was more effective in terms of seed survival rate when embryos were cultured on Murashige and Skoog (MS) medium supplemented with 3% sucrose, 0.2% active carbon, 400 mg L^-1 glutamine at 14 days after pollination (DAP), with a frequency of 6.67%. Putative hybrids (genome: ABC) were confirmed by RAPD technique and flow cytometry analysis. When nodal segments of the hybrids were treated using liquid medium with added colchicine, the allohexaploid was subsequently obtained, as affirmed by flow cytometry analysis and morphological observation. The synthesized hybrids showed unique traits compared with the parents. The synthesized hexaploid Brassica with A, B, and C genomes is not only assumed to have very good potential to create new crops for agriculture, but also to supply a basis for further investigation of the mechanism of plant evolution and adaptation.