Bacillus velezensis inhibits fusarium oxysporum growth, induces systemic resistance to CMV

Bacillus velezensis manifests robust biocontrol activity against fungal plant pathogens; however, its antiviral activity has rarely been investigated. Bacillus velezensis strain PEA1 was isolated, characterized, and evaluated for antifungal and antiviral activities against Fusarium oxysporum and cucumber mosaic virus (CMV).

The findings proved that strain PEA1 had intense antagonist activity against F.oxysporum. Under greenhouse conditions, the antiviral activities (protective, curative, and inactivation) of PEA1-culture filtrate (CF) on Datura stramonium plants were assayed, using a half-leaf method.

The inactivation treatment exhibited the highest inhibition rate (97.56%) and the most considerable reduction of CMV-CP accumulation 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 of PAL, CHS, HQT, PR-1, and POD genes in D. stramonium leaves 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. velezensis can be considered as a potential source for the production of bioactive compounds for the management of plant diseases.