The shift is happening in a greenhouse, not a factory line. Researchers have engineered tobacco and lettuce plants that carry the gene for myoglobin, the iron-rich protein in animal muscle, inside their chloroplasts. The study appeared in Frontiers in Plant Science on August 6, 2026.
Why it matters to alt-meat makers: myoglobin is what gives beef and pork their metallic, umami taste, and the oxygen bound to it is why a burger patty changes colour as it cooks. Plant-based products struggle to copy that.
Who is behind it
First author Alexia Groff is a researcher at Imperial College London. Co-author Kyoko Morimoto is chief scientific officer at Kyomei, a Cambridge-based plant biotechnology startup that partly funded the work. Groff told ScienceAlert the study shows “for the first time” that higher plants can stably produce myoglobin, “at a time when the demand for sustainable food production platforms is greater than ever.”
How they did it
The team cloned pig and cattle myoglobin genes and fired copies into the chloroplasts of tobacco and lettuce seedlings with a “gene gun.” Some seedlings took up the gene. Those plants grew to adulthood, flowered and passed the transgene to their offspring. For comparison, the authors also put the gene into the nuclear genome of both species and into the chloroplast of a single-celled alga, Chlamydomonas reinhardtii.
Why chloroplasts? “Due to their bacterial ancestry and their high number of copies per cell, chloroplasts are generally much better at making large amounts of protein than the cell nucleus,” Groff said. Tobacco served as the model plant. Lettuce was chosen because it is edible and could one day supply food ingredients.
Yields came to approximately 800 mg per kilogram of dry weight in tobacco and 810 mg in lettuce, at least three times what tobacco manages when the gene goes into the nuclear genome. Real meat holds far more. The researchers wrote that animal muscle is around 10-fold higher.
One surprise, Groff said, was how well the plants coped. “The transformed plants remained healthy, fertile, and showed no significant impairment of photosynthesis.”
Limits
Heme is the sticking point. The protein folds correctly, Groff said, but heme incorporation is incomplete, so heme availability looks like a bottleneck. Future work could target the plant’s heme pathway.
The authors argue plant-derived myoglobin could match or beat livestock on protein yield per hectare while using far less water and producing fewer greenhouse gas emissions. They acknowledge more studies are needed to compare it properly with livestock, and they describe the work as a proof of principle. The myoglobin could be pulled from leaves and purified as an ingredient for plant-based meat, Groff said. Morimoto added that edible lettuce modified this way might one day serve as a heme-iron-enriched food, “depending on legislative approval.”
Sources
- Powerhouses for fake meat: muscle protein can now be grown in chloroplasts of lettuce and tobacco plants
- A Key Meat Protein Has Been Grown in Lettuce For The First Time : ScienceAlert
