Enhancement of Folate Levels in Lettuce via a Methylotrophic Symbiont

Pink‐Pigmented Facultatively Methylotrophic (PPFM) bacteria are distributed ubiquitously in the phyllosphere of plants where they participate in a unique symbiotic relationship. By utilizing methanol released by the plant as a carbon source, they secrete compounds that increase plant growth and yield. Previous research has shown that plants, such as lettuce ( Lactuca sativa) , hosting mutant PPFMs that overexpress and secrete specific metabolites, such as vitamin B12 and methionine, accumulate these metabolites in their foliage and seeds. We have selected folate overproducing PPFMs on the basis of their resistance to the antifolate methotrexate. Their capability to over secrete folate will be tested by their ability to rescue a folate auxotroph ( Bacillus subtilis BKE0070). Levels of folate production will be determined by microbial or ELISA assay. We expect that bacterization of seeds with our folate overproducing and secreting mutants will result in folate enriched lettuce leaves. Folate is essential in the diets of humans for critical cellular pathways, such as DNA replication, and influences the uptake of other metabolically important B vitamins. If folate accumulation in lettuce leaves is successful, future experiments will be repeated on the agriculturally significant legume, Glycine max (soybean) .