ARS | Publication request: Enhancing the value of cottonseed as a source of feed and food by RNAi-mediated, selective and substantial reduction in seed-gossypol

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 5, 2008
Publication Date: N/A

Technical Abstract: In 2006, 44.2 million metric tons (MMT) of cottonseed was produced worldwide as a by-product of 24.8 MMT of cotton lint production (FAO Stat). This amount of cottonseed, containing nearly 10 MMT of protein, can potentially provide the protein requirement for 500 million people per year at a rate of 50g protein/day. However, gossypol, a toxic terpenoid present in the glands, renders cottonseed unfit as food and as feed for non-ruminant animals. A major portion of this abundant agricultural resource is utilized simply as feed for ruminant animals either as whole seeds or as meal following oil extraction. Therefore, elimination of gossypol from cottonseed has been a long-standing goal of geneticists. We have successfully used RNAi to disrupt gossypol biosynthesis in the seed by interfering with the expression of the o-cadinene synthase gene during embryo development. We demonstrate that it is possible to reduce significantly the levels of cottonseed-gossypol in a stable and heritable manner. Results from enzyme activity and molecular analyses on developing embryos were consistent with the observed phenotype in the mature seeds. Most importantly, the levels of gossypol and related terpenoids that are derived from the same pathway were not diminished in the foliage and floral parts of these plants and thus remain available for defense against insects and diseases. Thus, a targeted genetic modification, applied to an underutilized agricultural byproduct, provides a mechanism to open up a new source of nutrition for hundreds of millions of people.