Genome-wide identification and functional characterization of RxLR effectors in <i>Phytophthora cinnamomi</i> infecting <i>Carya cathayensis</i> Sarg

<i>Phytophthora cinnamomi</i> is a globally distributed oomycete pathogen capable of infecting over 5,000 plant species, causing devastating root rot and stem canker diseases with significant agricultural and ecological impacts. Similar to other <i>Phytophthora</i> species, <i>P. cinnamomi</i> secretes RxLR effectors to suppress host immunity and facilitate infection. Here, we present a high-quality genome assembly of <i>P. cinnamomi</i> strain ST402 isolated from an economically important Chinese hickory (<i>Carya cathayensis</i> Sarg.), revealing 146 putative RxLR effectors. Transcriptomic profiling during the early infection stages (0-36 h post-inoculation) identified 66 differentially expressed RxLR effectors, with 4 highly induced candidates (PciRxLR1, PciRxLR21, PciRxLR57, and PciRxLR69) demonstrating cell death suppression activity against pathogen-associated molecular patterns (PAMPs) and promoting <i>Phytophthora</i> pathogenicity in <i>Nicotiana benthamiana</i>. Subcellular localization revealed distinct nuclear and cytoplasmic targeting patterns of these effectors. Our findings provide critical insights into the molecular mechanisms underlying <i>P. cinnamomi</i> virulence and lay the foundation for developing targeted control strategies against this destructive pathogen.