<i>Verticillium dahliae</i> LysM effectors differentially contribute to virulence on plant hosts

<jats:title>Summary</jats:title><jats:p>Chitin‐binding lysin motif (LysM) effectors contribute to the virulence of various plant‐pathogenic fungi that are causal agents of foliar diseases. Here, we report the LysM effectors of the soil‐borne fungal vascular wilt pathogen <jats:italic>Verticillium dahliae</jats:italic>. Comparative genomics revealed three core LysM effectors that are conserved in a collection of <jats:italic>V. dahliae</jats:italic> strains. Remarkably, and in contrast with the previously studied LysM effectors of other plant pathogens, no expression of core LysM effectors was monitored <jats:italic>in planta</jats:italic> in a taxonomically diverse panel of host plants. Moreover, targeted deletion of the individual LysM effector genes in <jats:italic>V. dahliae</jats:italic> strain JR2 did not compromise virulence in infections on Arabidopsis, tomato or <jats:italic>Nicotiana benthamiana</jats:italic>. Interestingly, an additional lineage‐specific LysM effector is encoded in the genome of <jats:italic>V. dahliae</jats:italic> strain VdLs17, but not in any other <jats:italic>V. dahliae</jats:italic> strain sequenced to date. Remarkably, this lineage‐specific effector is expressed <jats:italic>in planta</jats:italic> and contributes to the virulence of <jats:italic>V. dahliae</jats:italic> strain VdLs17 on tomato, but not on Arabidopsis or <jats:italic>N. benthamiana</jats:italic>. Functional analysis revealed that this LysM effector binds chitin, is able to suppress chitin‐induced immune responses and protects fungal hyphae against hydrolysis by plant hydrolytic enzymes. Thus, in contrast with the core LysM effectors of <jats:italic>V. dahliae</jats:italic>, this lineage‐specific LysM effector of strain VdLs17 contributes to virulence <jats:italic>in planta</jats:italic>.</jats:p>