Bacillus velezensis PEA1 Inhibits Fusarium oxysporum Growth and Induces Systemic Resistance to Cucumber Mosaic Virus

Bacillus velezensismanifests robust biocontrol activity against fungal plant pathogens; however, its antiviral activity has rarely been investigated.Bacillus velezensisstrain PEA1 was isolated, characterized, and evaluated for antifungal and antiviral activities againstFusarium oxysporumMT270445 and cucumber mosaic virus (CMV) MN594112. Our findings proved that strain PEA1 had intense antagonist activity againstF.oxysporum. Under greenhouse conditions, the antiviral activities (protective, curative, and inactivation) of PEA1-culture filtrate (CF) onDatura stramoniumplants were assayed, using a half-leaf method. The inactivation treatment exhibited the highest inhibition rate (97.56%) and the most considerable reduction ofCMV-CPaccumulation levels (2.1-fold) in PEA1-CF-treated plants when compared with untreated plants (26.9-fold). Furthermore, PEA1-CF induced systemic resistance with significantly elevated transcriptional levels ofPAL,CHS,HQT,PR-1, andPODgenes inD.stramoniumleaves after all treatments. Gas chromatography-mass spectrometry analysis showed that pyrrolo[1,2-a]pyrazine-1,4-dione is the main compound in the PEA1-CF ethyl acetate extract, which may act as an elicitor molecule that induces plant systemic resistance and inhibits both fungal growth and viral replication. Consequently,B. velezensiscan be considered as a potential source for the production of bioactive compounds for the management of plant diseases. To our knowledge, this is the first report of the antiviral activity ofB.velezensisagainst plant viral infection.