Draft genome sequence of the ricin-producing oilseed castor bean

Castor bean (Ricinus communis) is an oil crop that belongs to the spurge (Euphorbiaceae) family. Its seeds are the source of castor oil, used for the production of high-quality lubricants due to its high proportion of the unusual fatty acid ricinoleic acid. Castor bean seeds also produce ricin, a highly toxic ribosome inactivating protein, making castor bean relevant for biosafety. We report here the 4.6X draft genome sequence of castor bean, representing the first reported Euphorbiaceae genome sequence. Our analysis shows that most key castor oil metabolism genes are single-copy while the ricin gene family is larger than previously thought. Comparative genomics analysis suggests the presence of an ancient hexaploidization event that is conserved across the dicotyledonous lineage.