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SUMMARY

Land plants include angiosperms, bryophytes, lycophytes and ferns, each of which may deploy distinct strategies to resist pathogens. Here, we investigate fern-pathogen interactions by characterizing novel pathosystems and analysing the diversity of fern immune receptors.

A collection of fern species was inoculated with a diverse set of microbes, and disease symptoms were assessed. We further leveraged published genome mining tools to analyse the diversity of RECEPTOR-LIKE KINASES, RECEPTOR-LIKE PROTEINS (RLKs/RLPs) and NUCLEOTIDE-BINDING AND LEUCINE-RICH REPEATS (NLRs), along with key immune signalling components, in ferns.

Our results reveal that ferns exhibit a range of responses to pathogens, including non-host resistance and specific resistance mechanisms. Among ten ferns tested,Pteris vittatadisplays the broadest spectrum of pathogen compatibility. Genome mining indicates that ferns encode a diverse repertoire of putative immune receptors, antimicrobial peptides and mediators of systemic acquired resistance. Ferns possess numerous RLKs/RLPs, resembling those required for cell-surface immunity in angiosperms. They also encode diverse NLRs, including a previously undescribed class with a disordered N-terminal domain, termed disN-NLR.

These findings provide insights into disease resistance evolution and open promising perspectives for crop protection strategies.