Scientists turn lettuce into a factory for a key meat protein Researchers engineered lettuce and tobacco chloroplasts to produce myoglobin, a key protein behind meat's color, flavor and iron content. "Here we show that plants can be engineered to produce the animal protein myoglobin (Mb) in their chloroplasts, the energy factories for photosynthesis. The results are published in Frontiers in Plant Science ("Sustainable production of myoglobin meat protein in plant chloroplasts"). They then used a so-called ‘gene gun’ to shoot gene copies physically into the chloroplasts of tobacco and lettuce seedlings in the laboratory. Since it is identical to animal myoglobin, it could then be added as an ingredient to plant-based meat products to improve their color, flavor and nutritional value," explained Groff.