A bird’s-eye view: exploration of the flavin-containing monooxygenase (FMO) superfamily in common wheat

The Flavin Monooxygenase ( FMO ) gene superfamily in plants is involved in various processes most widely documented for its involvement in auxin biosynthesis, specialized metabolite biosynthesis, and plant microbial defense signalling. The roles of FMOs in defense signaling and disease resistance have recently come into focus as they may present opportunities to increase immune responses in plants including leading to systemic acquired resistance, but are not well characterized. We present a comprehensive catalogue of FMO s found in genomes across vascular plants and explore, in depth, 170 wheat TaFMO genes for sequence architecture, cis- acting regulatory elements, and changes due to Transposable Element insertions. A molecular phylogeny separates TaFMOs into three clades (A, B, and C) for which we further report gene duplication patterns, and differential rates of homoeologue expansion and retention among TaFMO subclades. We discuss Clade B TaFMOs where gene expansion is similarly seen in other cereal genomes. Transcriptome data from various studies point towards involvement of subclade B2 TaFMO s in disease responses against both biotrophic and necrotrophic pathogens, substantiated by promoter element analysis. We hypothesize that certain TaFMOs are responsive to both abiotic and biotic stresses, providing potential targets for enhancing disease resistance, plant yield and other important agronomic traits. Altogether, FMOs in wheat and other crop plants present an untapped resource to be exploited for improving the quality of crops. ### Competing Interest Statement The authors have declared no competing interest. * FMO : Flavin-containing monooxygenase ‘nc’ : non-canonical FAD : flavin adenine dinucleotide NAD(P)H : nicotinamide adenine dinucleotide phosphate MSA : multiple sequence alignment FPKM : Fragments Per Kilobase of transcript per Million mapped reads Tpm : transcripts per million