Pectin acetylesterase PAE5 is associated with the virulence of plant pathogenic oomycete Peronophythora litchii

Pectin is a major component of the primary cell wall of higher plants. Some galacturonyl residues in pectin are often O-acetylated. Pectin acetylesterases (PAEs) involved in enzymatic deacetylation of pectin are widespread in the plant pathogenic oomycetes and show sequence and transcriptional polymorphism. Peronophythora litchii is the most destructive pathogens known on lychee (Litchi chinensis Sonn). Out of the 38 PAEs predicted from sequence analysis of P. litchii, Phytophthora species and Pythium species, five P. litchii PAE genes were selected for further study. Of these, P. litchii PAE4 and PAE5, named PlPAE4 and PlPAE5, were knocked out using CRISPR/Cas9 technique. The plpae5 mutants were less capable of host invasion than the wild-type P. litchii strain SHS3, as tested by lychee plant inoculation. Heterologous expression of PlPAE5 in Nicotiana benthamiana could promote the infection by Phytophthora capsici. These results demonstrate that PlPAE5 plays an important role in oomycete pathogenicity.