Verticillium longisporum phospholipase VlsPLA₂ is a virulence factor that targets host nuclei and modulates plant...

Phospholipase A₂ (PLA₂ ) is a lipolytic enzyme that hydrolyses phospholipids in the cell membrane. In the present study, we investigated the role of secreted PLA₂ (VlsPLA₂ ) in Verticillium longisporum, a fungal phytopathogen that mostly infects plants belonging to the Brassicaceae family, causing severe annual yield loss worldwide. Expression of the VlsPLA₂ gene, which encodes active PLA₂ , is highly induced during the interaction of the fungus with the host plant Brassica napus. Heterologous expression of VlsPLA₂ in Nicotiana benthamiana resulted in increased synthesis of certain phospholipids compared to plants in which enzymatically inactive PLA₂ was expressed (VlsPLA₂ ^ΔCD ). Moreover, VlsPLA₂ suppresses the hypersensitive response triggered by the Cf4/Avr4 complex, thereby suppressing the chitin-induced reactive oxygen species burst. VlsPLA₂ -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. VlsPLA₂ was initially localized to the host nucleus and then translocated to the chloroplasts at later time points. In addition, VlsPLA₂ bound to the vesicle-associated membrane protein A (VAMPA) and was transported to the nuclear membrane. In the nucleus, VlsPLA₂ 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 VlsPLA₂ acts as a virulence factor, possibly by hydrolysing host nuclear envelope phospholipids, which, through a signal transduction cascade, may suppress basal plant immune responses.