Oomycete pathogen pectin acetylesterase targets host lipid transfer protein to reduce salicylic acid signaling.

This article investigates the virulence mechanism of the oomycete pathogen Peronophythora litchii pectin acetylesterase PlPAE5 in suppressing plant immunity. The study demonstrates that PlPAE5 interacts with the litchi lipid transfer protein LcLTP1 via its pectin acetylesterase (PAE) domain, destabilizing LcLTP1 and thereby subverting LcLTP1-mediated salicylic acid (SA) signaling and plant defense. Overexpression of LcLTP1 enhances resistance to oomycete and fungal pathogens in Nicotiana benthamiana, dependent on the receptor-like kinases BAK1 and SOBIR1, and activates SA-related immune responses. The enzymatic activity of PlPAE5 is not required for its virulence function, which relies on its ability to bind and destabilize LcLTP1, highlighting a novel pathogen strategy targeting plant lipid transfer proteins to suppress SA-mediated immunity. These findings provide insights into plant–oomycete interactions and suggest potential targets for breeding disease-resistant crops.