Verticillium dahliae strains that infect the same host plant display highly divergent effector catalogs

Abstract

During host colonization, plant pathogens secrete molecules that enable host colonization, also known as effector proteins. Here, we show that strains of the fungal plant pathogen Verticillium dahliae that are able to infect the same host plant harbour highly divergent LS effector repertoires. Our study outlines the variability within LS effector gene repertoires of V. dahliae strains, which may allow the various strains to be competitive in the co-evolution with their hosts. Summary Effectors are proteins secreted by pathogens to support colonization of host plants, often by deregulating host immunity. Effector genes are often localized within dynamic lineage-specific (LS) genomic regions, allowing rapid evolution of effector catalogues. Such localization permits pathogens to be competitive in the co-evolutionary arms races with their hosts. For a broad host-range pathogen such as Verticillium dahliae it is unclear to what extent single members of their total effector repertoires contribute to disease development on multiple hosts. Here, we determined the core and LS effector repertoires of a collection of V. dahliae strains, as well as the ability of these strains to infect a range of plant species comprising tomato, cotton, Nicotiana benthamiana, Arabidopsis, and sunflower to assess whether the presence of particular LS effectors correlates with the ability to infect particular plant species. Surprisingly, we found that V. dahliae strains that are able to infect the same host plant harbor highly divergent LS effector repertoires. Furthermore, we observed differential V. dahliae core effector gene expression between host plants. Our data suggest that different V. dahliae lineages utilise divergent effector catalogs to colonize the same host plant, suggesting considerable redundancy among the activities of effector catalogs between lineages.