Tetrahydrofolate biosynthesis and distribution in higher plants

One-carbon transfer reactions are mediated by H₄F (tetrahydrofolate), a soluble coenzyme (vitamin B₉) that is synthesized de novo by plants and microorganisms, and absorbed from the diet by animals. H₄F synthesis in plants is quartered between the plastids, the cytosol and the mitochondria, a spatial distribution that is not observed in the other organisms and that suggests a complex intracellular traffic. Also, the activity of H₄F synthesis fluctuates during plant growth, depending on the tissue and the developmental stage of the seedling, thus illustrating the flexibility of one-carbon metabolism in these organisms. This paper will focus on our recent knowledge about H₄F synthesis in the plant cell and will briefly describe the activity of the pathway during the growth and development of the seedling.