Development of a Brassica napus (Canola) Crop Containing Fish Oil-Like Levels of DHA in the Seed Oil
James R. Petrie, Xue‐Rong Zhou, Antonio Leonforte, Jason McAllister, Pushkar Shrestha, Yoko Kennedy, Srinivas Belide, Greg Buzza, N. N. Gororo, Wenxiang Gao, Geraldine Lester, Maged P. Mansour, Roger J. Mulder, Qing Liu, Lijun Tian, Claudio Silva, Noel O. I. Cogan, Peter D. Nichols, Allan Green, Robert de Feyter, Malcolm D. Devine, Surinder Singh
Abstract
Plant seeds have long been promoted as a production platform for novel fatty acids such as the long-chain omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) commonly found in fish oil. In this article we describe the development of a canola (Brassica napus) variety producing fish oil-like levels of DHA in the seed. This was achieved by the introduction of a microalgal/yeast transgenic pathway of seven consecutive enzymatic steps which converted the native substrate oleic acid to α-linolenic acid and, subsequently, to EPA, docosapentaenoic acid (DPA) and DHA. This paper describes construct design and evaluation, plant transformation, event selection, field testing in a wide range of environments, and oil profile stability of the transgenic seed. The stable, high-performing event NS-B50027-4 produced fish oil-like levels of DHA (9-11%) in open field trials of T3 to T7 generation plants in several locations in Australia and Canada. This study also describes the highest seed DHA levels reported thus far and is one of the first examples of a deregulated genetically modified crop with clear health benefits to the consumer.