P-043 - Identification of novel PAMP proteins from Phytophthora capsici

Pathogens secrete molecules that can trigger plant immune responses, known as pathogen-associated molecular patterns (PAMPs). Phytophthora capsici, an oomycete pathogen with economic importance, releases numerous molecules; however, their identity and roles as PAMPs remain largely unknown. Here, we confirmed that the secreted proteins from P. capsici induce cell death and activated MAPK cascade in plants. To identify PAMP candidates from secreted proteins, we employed a combination of analyses, including size-exclusion chromatography, mass spectrometry analysis, and bioinformatics approaches. Sixty-four putative PAMP proteins were selected as final candidates, and their ability to induce cell death or activate plant defense responses was investigated. Among these, we focused on CF16, an uncharacterized protein that is conserved in oomycete pathogens. Structural analysis via Alphafold2 and Foldseek suggests that CF16 has lipid-binding activity, with homologs exhibiting structural conservation despite low sequence similarity. This protein not only induces cell death but also triggers defense responses in Nicotiana benthamiana plants when transiently expressed via agroinfiltration or delivered as recombinant protein, suggesting its role as a novel PAMP. This study would provides valuable insights into PTI mechanisms in plant-oomycete interactions.