Integrative approach to identify robust pattern recognition receptors in Eucalyptus grandis: novel candidates for...

Pattern-recognition receptors (PRRs) initiate plant pattern-triggered immunity (PTI), encompassing receptor-like kinases (RLKs) and receptor-like proteins (RLPs). Eucalyptus grandis, an economically important species worldwide, is a long-lived organism that faces multiple disease pressures. The deployment of PRR-based breeding tools offers a route to broad, non-race-specific resistance that can remain effective across outbreaks. The objective of this work was to identify and characterise the PRR repertoire of E. grandis using public multi-omics data. Two state-of-the-art predictors were compared with a multi-species curation and a meta-analysis was conducted compiling transcriptomic data under biotic stress. A set of 730 RLKs/RLPs (PRR candidates) were consistently identified across three sources (~ 1.6% of protein-coding genes), of which 283 were differentially expressed (RLKs/RLPs-DEG). A PFAM domain-based scheme was applied to standardise classification across tools. RLKs (TM-K-LRR) predominated over RLPs (TM-LRR), while many carried malectin or malectin-like ectodomains. RLKs/RLPs genes were unevenly distributed across the genome: chromosome 6 had the highest count and the densest clustering. Gene-family expansion appeared mainly driven by duplication, with extensive tandem arrays supported by segmental, proximal and dispersed events. Gene Ontology and cis-elements annotations in RLKs/RLPs-DEG/no-DEG showed significant enrichment in terms related to cell cycle development, hormonal regulation and stress response. We proposed a catalogue of 16 RLKs which resulted in DEGs against at least three pathogens, suggesting their broad spectrum and robustness. Most of them presented orthologues with cross-taxon evidence of defence roles. This study delineates novel multi-pathogen candidate PRR genes, providing valuable information to assist Eucalyptus breeding programs.