Oily fish such as salmon are the best dietary source of the Omega-3 oils eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which have been proven to improve heart health and aid neurodevelopment in children, but the oils can also be extracted from the livers of other fish such as cod for use as a dietary supplement. Demand for Omega-3 oils is increasing, and with the pressure on fish stocks already great, the researchers, led by Rothamsted Research’s Johnathan Napier and Olga Sayanova, sought an alternative source.
Napier and the team genetically engineered the oilseed crop false flax, Camelina sativa, to produce EPA and DHA in its seeds. The researchers chose false flax as it already produces large amounts of an oil called a-linolenic acid (ALA), an important precursor to EPA and DHA. Omega-3 oils are generally produced by tiny photosynthetic phytoplankton in the sea such as diatoms and unicellular algae, which are eaten by small fish which are in turn consumed by larger fish like salmon, leading to the accumulation of the oils. The small fish may also be caught to produce meal for farmed fish.
Sayanova says that the researchers first identified the genes responsible for EPA and DHA production in phytoplankton. These genes were inserted into the false flax genome in varying proportions.
“In the first instance, we introduced five genes and on average 24% of the total oil content in the plant seed was EPA. Then we introduced seven genes and in that case on average 8% of the total oil content in the seed of the plant was DHA and 11% EPA. We had instances that these percentages were 14% and 12% respectively. The average accumulation of these oils in the transgenic Camelina plants is comparable to those found in fish oil but Camelina makes none of these naturally,” she says.
Napier says that the engineered plants are a sustainable, terrestrial source of Omega-3 oils which could have benefits both for human health and the marine environment.
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