cultivars. B. juncea (AABB) is estimated to have originated 39,000–55,000 years ago. As of 2020, research on organellar genomes shows that B. nigra (BB) is likely the "mother" of B. carinata (BBCC) and that B. rapa (AA) likely mothered B. juncea. The situation with B. napus (AACC) is more complex: some specimens have a rapa-like organellar genome, while the rest indicate an ancient, unidentified maternal plant. Data from molecular studies indicate the three diploid species are themselves paleohexaploids. Allohexaploid species In 2011 and 2018, novel allohexaploids (AABBCC) located at the "center" of the triangle of U were created by different means, for example by crossing B. rapa (AA) with B. carinata (BBCC), or B. nigra (BB) with B. napus (AACC), or B. oleracea (CC) with B. juncea (AABB), followed by chromosome duplication of the triploid (ABC) offspring to generate doubled haploid (AABBCC) offspring. In addition, two stable allohexaploid (AABBSS) intergeneric hybrids between Indian mustard (B. juncea, AABB) and white mustard (Sinapsis alba, SS) were created in 2020 by protoplast fusion. See also Cultivar Hybridisation References Genetics Brassica Hybrid plants