P-149 - Cracking the code on Phytophthora cinnamomi CRN effectors and their role in plant cell death

Phytophthora cinnamomi is a globally significant soil-borne oomycete pathogen causing root rot in over 5,000 plant species. Despite its impact, research on the effectors of P. cinnamomi has been stagnant. P. cinnamomi is believed to manipulate host cell death through effectors, such as Crinkling and Necrosis proteins (CRNs). This study aimed to functionally characterize P. cinnamomi CRNs and their role in manipulating host cell death. CRN candidates were identified through RNA-seq expression, phylogenetics, and protein structure predictions. Cell death induction and suppression assays in Nicotiana benthamiana were performed via Agrobacterium-mediated transformation. Additionally, the subcellular localization of candidate CRNs was determined using confocal microscopy to further elucidate their potential modes of action. Of the candidate CRNs, most localized to the nucleus as expected, while two localized to the cytoplasm, suggesting diverse modes of action within the P. cinnamomi CRN repertoire. CRN52 was found to induce cell death, whereas CRN11_1 did not, which aligns with the in silico predicted functions. From this, candidate CRNs can now be selected for functional characterization using gene editing tools such as CRISPR-Cas; to further enhance our understanding of how these effectors contribute to P. cinnamomi pathogenesis and virulence, identifying plant resistance targets, and aiding the development of resistant rootstocks and disease control strategies.