US regulators in October approved a transgenic cotton plant that produces edible seed. The plant, developed by Texas A&M AgriLife Research in College Station, is genetically engineered to greatly reduce the expression of the antinutrient gossypol in its seed, making it edible for humans and animals. Gossypol is a naturally occurring plant pigment produced in the glands of cotton that is toxic to insects and serves as a natural defense mechanism against pests. The pigment can also be toxic to humans and most monogastric animals, such as pigs, birds, fish and rodents, when consumed at high levels. Keerti Rathore and his colleagues at Texas A&M modified the cotton (Gossypium hirsutum) by silencing, with RNA interference, the genes in the seed that encode δ-cadinene synthase, a key enzyme in gossypol biosynthesis. This lowers gossypol in the seed by 97%, to 300 parts per million—below the US Food and Drug Administration's safety threshold. The rest of the cotton plant maintains normal levels of gossypol, enabling the plant to keep its inherent pest defenses. The technology could increase the value of cottonseed to farmers and others along the commercial chain, and provide a new protein source for humans and animals, Rathore says. The cotton plant triggered regulatory oversight by the US Department of Agriculture (USDA) because it was transformed using Agrobacterium tumefaciens, which the agency considers a “plant pest.” The agency in August also approved for commercialization genetically engineered canola seed with increased levels of docosahexaenoic acid (DHA), an omega-3 fatty acid, developed by Nuseed in Breckenridge, Minnesota. Meanwhile, the USDA has increasingly given free passes to plants genetically altered using CRISPR, enabling the plants to be commercialized without the agency's oversight (Nat. Biotechnol. 36, 6–7, 2018). That includes, most recently, a camelina line from Yield10 Bioscience in Woburn, Massachusetts, and a pennycress line from Illinois State University in Normal, Illinois, both with undisclosed phenotypes.
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Gossypol but not cottonseed extracts or lipopolysaccharides stimulates HuR gene expression in mouse cells
Journal of Functional Foods (2019)
Journal of Phycology (2019)