“…Similarly, plants of B. juncea were formed from crosses between B. campestris and B. nigra (56,72,93,107) , and plants of B. carinata from crosses between B. oleracea and B. nigra (57,73,75) . There also is cytological evidence that the three elemental genomes are themselves secondary polyploids, probably originating from a common ancestor with a basic chromosome number of 5 or 6 (2,29,30,60,72,109,110,120). The genera Sinapis, Eruca and Raphanus also may have evolved from this same progenitor (58,60,72).…”