Identification and Characterization of a Red-Light Sensor FphA in Aspergillus flavus

<i>Aspergillus flavus</i> (<i>A. flavus</i>) is a common contaminant of food and feed due to the production of aflatoxin B₁, which is susceptible to environmental signals. Nevertheless, how red light plays a role in <i>A. flavus</i> remains unclear. Here, we identified the uncharacterized hypothetical protein G4B84_010091 as a red-light sensor, defined as fungal phytochrome A (FphA), in <i>A. flavus</i>. The <i>fphA</i> knockout strain (Δ<i>fphA</i>) and complementary strain (<i>fphA</i>-com) were successfully constructed to characterize the function of FphA. Our results indicated that aflatoxin B₁ biosynthesis was promoted, while the development of conidia and sclerotia as well as the infection of peanuts were impaired in Δ<i>fphA</i> when compared with WT or <i>fphA</i>-com. The FphA^ΔRR domain deletion mutant exhibited all the phenotypes observed in the Δ<i>fphA</i> strain, indicating that the RR domain is indispensable for the function of FphA. In summary, FphA is involved not only in the formation of spores and sclerotia, but also in aflatoxin B₁ biosynthesis and the pathogenicity of <i>A. flavus</i>, which offers a potential target for novel approaches to controlling the dispersal and toxin production of this fungus.