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

Aspergillus flavus (A. flavus) 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 A. flavus remains unclear. Here, we identified the uncharacterized hypothetical protein G4B84_010091 as a red-light sensor, defined as fungal phytochrome A (FphA), in A. flavus. The fphA knockout strain (ΔfphA) and complementary strain (fphA-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 ΔfphA when compared with WT or fphA-com. The FphA^ΔRR domain deletion mutant exhibited all the phenotypes observed in the ΔfphA 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 A. flavus, which offers a potential target for novel approaches to controlling the dispersal and toxin production of this fungus.