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.
(© 2023 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.)