Verticillium longisporum phospholipase VlsPLA(2) is a virulence factor that targets host nuclei and modulates plant immunity

Phospholipase A(2) (PLA(2)) is a lipolytic enzyme that hydrolyses phospholipids in the cell membrane. In the present study, we investigated the role of secreted PLA(2) (VlsPLA(2)) in Verticillium longisporum, a fungal phytopathogen that mostly infects plants belonging to the Brassicaceae family, causing severe annual yield loss worldwide. Expression of the VlsPLA (2) gene, which encodes active PLA(2), is highly induced during the interaction of the fungus with the host plant Brassica napus. Heterologous expression of VlsPLA(2) in Nicotiana benthamiana resulted in increased synthesis of certain phospholipids compared to plants in which enzymatically inactive PLA(2) was expressed (VlsPLA(2) (ΔCD)). Moreover, VlsPLA(2) suppresses the hypersensitive response triggered by the Cf4/Avr4 complex, thereby suppressing the chitin‐induced reactive oxygen species burst. VlsPLA(2)‐overexpressing V. longisporum strains showed increased virulence in Arabidopsis plants, and transcriptomic analysis of this fungal strain revealed that the induction of the gene contributed to increased virulence. VlsPLA(2) was initially localized to the host nucleus and then translocated to the chloroplasts at later time points. In addition, VlsPLA(2) bound to the vesicle‐associated membrane protein A (VAMPA) and was transported to the nuclear membrane. In the nucleus, VlsPLA(2) caused major alterations in the expression levels of genes encoding transcription factors and subtilisin‐like proteases, which play a role in plant immunity. In conclusion, our study showed that VlsPLA(2) acts as a virulence factor, possibly by hydrolysing host nuclear envelope phospholipids, which, through a signal transduction cascade, may suppress basal plant immune responses.