Functional analysis of the Nep1-like proteins from .

Necrosis and ethylene-inducing peptide 1 (Nep1) -like proteins (NLP) are secreted by multiple taxonomically unrelated plant pathogens (bacteria, fungi, and oomycete) and are best known for inducing cell death and immune responses in dicotyledonous plants. A group of putative genes from obligate biotrophic oomycete were predicted by RNA-Seq in our previous study, but their activity has not been established. Therefore, we analyzed the () family and identified seven genes. They all belong to type 1 genes and form a -specific cluster when compared with other pathogen genes. The expression of was induced during early infection process and the expression patterns could be categorized into two groups. -mediated transient expression assays revealed that only PvNLP7 was cytotoxic and could induce resistance in . Functional analysis showed that PvNLP4, PvNLP5, PvNLP7, and PvNLP10 significantly improved disease resistance of to . Moreover, the four genes caused an inhibition of plant growth which is typically associated with enhanced immunity when over-expressed in Arabidopsis. Further research found that PvNLP7 could activate the expression of defense-related genes and its conserved NPP1 domain was critical for cell death- and immunity-inducing activity. This record of genes from showed a functional diversification, laying a foundation for further study on pathogenic mechanism of the devastating pathogen.