Folates in legume root nodules

Folates are multifunctional metabolites in plants that are essential for cell division, nucleic acids and amino acid synthesis. During symbiotic nitrogen fixation in legumes, these cofactors are needed for de novo purine biosynthesis, meaning that changes in the folate pools could directly affect the flow of fixed nitrogen to the plant. Its role related to symbiotic nitrogen fixation has not been yet explored, but recent data suggest a relevant role during the first steps. Transcriptomic, metabolomic and proteomic analyses indicate that folates are accumulated in symbiotic plant tissue, as they are involved, not only in de novo purines biosynthesis, but in nitrogen translocation, endoreduplication and phytohormones biosynthesis. Understanding the possible implication of folate pools during the nitrogen fixation and assimilation, might aid for new engineering targets, in relation to the two transformylations or the production of glycine by serine hydroxymethyltransferase during the de novo purine biosynthetic pathway. In this review, we intend to deliver and discuss the available evidence that support a relevant role of folates during the symbiotic nitrogen fixation.