Raphanobrassica was developed by Karpechenko using:
In 1928 Georgi Karpechenko made first intentional intergeneric allopolyploid Raphanobrassica by crossing radish Raphanus sativus 2n=18 RR with cabbage Brassica oleracea 2n=18 CC, both from Brassicaceae family with similar chromosome numbers. Initial F1 hybrid RC 2n=18 was highly sterile with 9 radish and 9 cabbage chromosomes but no homologous partner for synapsis, showing mostly univalents at metaphase I and abortive gametes. Karpechenko discovered a few fertile seeds where somatic doubling had occurred spontaneously, yielding allotetraploid RRCC 2n=36 containing full diploid sets of both par
Ref: Karpechenko GD 1928 Z Pflanzenzucht – Raphanobrassica. Stebbins GL. Chromosomal Evolution