Heterologous Expression of SiFBP, a Folate-Binding Protein from Foxtail Millet, Confers Increased Folate Content and Altered Amino Acid Profiles with Nutritional Potential to .

The mechanism underlying folate degradation in foxtail millet grains remains unclear. Here, we identified ( folate-binding protein) from foxtail millet. A phylogenetic tree revealed that FBPs have close genetic relationships among cereal crop species. Docking analysis and heterologous expression of in yeast showed that it could bind folic acid (FA). The localized to the plasma membrane in tobacco mesophyll cells by transient expression. In , it was expressed specifically in the roots and germinating seeds. Overexpressing in yeast and significantly increased folate contents. Untargeted metabolome analysis revealed differentially accumulated metabolites between the transgenic lines (TLs) and wild type (WT); these metabolites were mainly enriched in the amino acid metabolism pathway. The relative contents of lysine and leucine, threonine, and l-methionine were significantly higher in the TLs than in WT. Genes related to the folate and lysine synthesis pathways were upregulated in the TLs. Thus, can be used for biofortification of folate and important amino acids in crops genetic engineering.