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.