Researchers have succeeded in making lettuce and tobacco plants produce myoglobin, a protein abundant in animal muscles and responsible for the red color, for the umami flavor and for part of the iron content of meat. The discovery could contribute to improving the taste, appearance and nutritional value of plant-based meat alternatives.
The study, published in Frontiers in Plant Science, demonstrates that it is possible to produce this protein directly in the chloroplasts of plants — the structures responsible for photosynthesis — by introducing an animal gene into their DNA.
“We showed that plants can be modified to produce the animal protein myoglobin (Mb) in their chloroplasts, the energy factories of photosynthesis. This could provide a more sustainable way of producing an important ingredient for plant-based products as alternatives to meat,” says Alexia Groff, a researcher at Imperial College London and the study’s principal author.
The team cloned genes for porcine and bovine myoglobin and introduced them into tobacco and lettuce plants using a technique known as a “gene gun,” which fires microscopic particles containing DNA into the interior of plant cells. The modified plants grew normally and transmitted the new gene to subsequent generations.
Production could rival livestock
Analyses revealed that the plants produced about 800 milligrams of myoglobin per kilogram of dry matter, a value far lower than that found in meat, which contains between 8.1 and 11.2 milligrams per gram of dry matter.
Nevertheless, the researchers argue that, due to high agricultural productivity and greater efficiency in resource use, myoglobin production per hectare could approach — or even surpass — that achieved through livestock farming.
“Despite this, plant cultivation is much more efficient in terms of resource use than livestock production; consequently, plant-derived myoglobin could achieve per-hectare yields comparable — or potentially higher — than those of animal production, while simultaneously benefiting from substantially lower water consumption and lower greenhouse gas emissions,” the authors wrote.
Ingredient for plant-based meat and fortified foods
According to the researchers, myoglobin could be extracted from the leaves and purified through industrial protein-purification processes, and then used as an ingredient in plant-based products to improve color, flavor and the nutritional value of meat alternatives.
“Myoglobin can be extracted from the leaves and purified using industrial protein purification methods. Because it is identical to animal myoglobin, it could then be added as an ingredient to plant-based meat alternatives to improve their color, flavor and nutritional value,” explains Alexia Groff.
The team also believes that, in the future, the genetically modified lettuce could be consumed directly as a heme iron-enriched food, the form of iron most readily absorbed by the body.
“We hope that lettuce expressing myoglobin could someday also serve as a biofortified food with heme iron, depending on legislative approval,” says Kyoko Morimoto, chief scientific officer of the plant biotechnology company Kyomei and coauthor of the study.
The researchers emphasize that the technology remains in an experimental phase and that any commercial application will depend on additional safety and efficacy assessments and on regulatory approvals.
