Genome-Wide Analysis of Fusarium oxysporum f. sp. cubense Peroxidases Reveals Oxidative-Stress Responses and Infection-Associated Expression

Banana Fusarium wilt, caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc), is a devastating disease and a major threat to global banana production. Here, we identified 24 genes predicted to encode heme-dependent peroxidase- or catalase–peroxidase-related proteins in Foc race 4 (Foc4), whereas nine genes encoding thiol-dependent peroxide-reducing proteins were catalogued separately. Phylogenetic, synteny, and Ka/Ks analyses indicated a conserved peroxidase repertoire under strong purifying selection, without substantial lineage-specific expansion. Motif, domain, gene-structure, and promoter analyses revealed subgroup-specific features and abundant putative stress- and hormone-responsive cis-regulatory motifs. Expression profiling during banana infection and H2O2 treatment showed distinct temporal and oxidative-stress responses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses linked subsets of these genes to antioxidant activity, peroxide metabolism, peroxisomal functions, and stress signaling. A F. oxysporum f. sp. lycopersici ortholog-based interaction network combined with co-expression analysis prioritized five peroxidases potentially associated with pathogenicity-related expression programs. FoCP, selected separately based on its rapid H2O2 response and catalase–peroxidase annotation, enhanced oxidative-stress tolerance when heterologously expressed in yeast. Overall, Foc4 appears to adapt to oxidative stress through condition-specific regulation of a conserved peroxidase repertoire rather than gene-family expansion. The network-prioritized peroxidases provide candidates for further functional and pathogenicity studies.