Transcriptome Analysis of mfs2 -Defective Penicillium digitatum Mutant to Reveal Importance of Pd mfs2 in Developing Fungal Prochloraz Resistance

Demethylation inhibitors (DMIs), including prochloraz, are popular fungicides to control citrus postharvest pathogens such as (green mold). However, many strains have developed prochloraz resistance, which decreases drug efficacy. Specific major facilitator superfamily (MFS) transporter gene , encoding drug-efflux pump protein MFS2, has been identified in strain F6 (PdF6) to confer fungal strain prochloraz resistance. However, except for the drug-efflux pump function of MFS2, other mechanisms relating to the Pd are not fully clear. The present study reported a transcriptome investigation on the -defective strain. Comparing to the wild-type strain, the -defective strain showed 717 differentially expressed genes (DEGs) without prochloraz induction, and 1221 DEGs with prochloraz induction. The obtained DEGs included multiple isoforms of MFS transporter-encoding genes, ATP-binding cassette (ABC) transporter-encoding genes, and multidrug and toxic compound extrusion (MATE) family protein-encoding genes. Many of these putative drug-efflux pump protein-encoding genes had significantly lower transcript abundances in the -defective strain at prochloraz induction, as compared to the wild-type strain, including twenty-two MFS transporter-encoding genes ( to ), two ABC transporter-encoding genes ( and ), and three MATE protein-encoding genes ( to ). The prochloraz induction on special drug-efflux pump protein genes in the wild-type strain was not observed in the -defective strain, including , , , , , and . On the other hand, the up-regulation of other drug-efflux pump protein genes in the -defective strain cannot recover the fungal prochloraz resistance, including , , , , , and to . The functional enrichment of DEGs based on Kyoto Encyclopedia of Genes and Genomes (KEGG), Clusters of Orthologous Groups (COG), and euKaryotic Orthologous Groups (KOG) database resources suggested some essential contributors to the -relating prochloraz resistance, including ribosome biosynthesis-related genes, oxidative phosphorylation genes, steroid biosynthesis-related genes, fatty acid and lipid metabolism-related genes, and carbon- and nitrogen-metabolism-related genes. The results indicated that the MFS2 transporter might be involved in the regulation of multiple drug-efflux pump protein gene expressions and multiple metabolism-related gene expressions, thus playing an important role in developing prochloraz resistance.