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Tomato (Solanum lycopersicum) is one of the world's most important food crops, and as such, its production needs to be protected from infectious diseases that can significantly reduce yield and quality. Here, we survey the effector-triggered immunity (ETI) landscape of tomato against the bacterial pathogen Pseudomonas syringae. We perform comprehensive ETI screens in five cultivated tomato varieties and two wild relatives, as well as an immunodiversity screen on a collection of 149 tomato varieties that includes both wild and cultivated varieties. The screens reveal a tomato ETI landscape that is more limited than what was previously found in the model plant Arabidopsis thaliana. We also demonstrate that ETI eliciting effectors can protect tomato against P. syringae infection when the effector is delivered by a non-virulent strain either prior to or simultaneously with a virulent strain. Overall, our findings provide a snapshot of the ETI landscape of tomatoes and demonstrate that ETI can be used as a biocontrol treatment to protect crop plants. Tomato production is threatened by pathogens such as Pseudomonas syringae. Here the authors screen a library of P. syringae effectors against a diverse collection of tomato accessions and identify six effector families that can potently induce effector triggered immunity. [ABSTRACT FROM AUTHOR]

Summary: The emergence of new pathogens is an ongoing threat to human health and agriculture. While zoonotic spillovers received considerable attention, the emergence of crop diseases is less well studied. Here, we identify genomic factors associated with the emergence of Pseudomonas syringae bacterial blight of coffee.Fifty‐three P. syringae strains from diseased Brazilian coffee plants were sequenced. Comparative and evolutionary analyses were used to identify loci associated with coffee blight. Growth and symptomology assays were performed to validate the findings.Coffee isolates clustered in three lineages, including primary phylogroups PG3 and PG4, and secondary phylogroup PG11. Genome‐wide association study of the primary PG strains identified 37 loci, including five effectors, most of which were encoded on a plasmid unique to the PG3 and PG4 coffee strains. Evolutionary analyses support the emergence of coffee blight in PG4 when the coffee‐associated plasmid and associated effectors derived from a divergent plasmid carried by strains associated with other hosts. This plasmid was only recently transferred into PG3. Natural diversity and CRISPR‐Cas9 plasmid curing were used to show that strains with the coffee‐associated plasmid grow to higher densities and cause more severe disease symptoms in coffee.This work identifies possible evolutionary mechanisms underlying the emergence of a new lineage of coffee pathogens. [ABSTRACT FROM AUTHOR]

Author(s): Elwira Smakowska-Luzan [1]; G. Adam Mott [2]; Katarzyna Parys [1]; Martin Stegmann [3]; Timothy C Howton [4]; Mehdi Layeghifard [2]; Jana Neuhold [5]; Anita Lehner [5]; Jixiang Kong [1]; [...]

Pathogenic effector proteins use a variety of enzymatic activities to manipulate host cellular proteins and favor the infection process. However, these perturbations can be sensed by nucleotide-binding leucine-rich-repeat (NLR) proteins to activate effector-triggered immunity (ETI). Here we have identified a small molecule (Zaractin) that mimics the immune eliciting activity of the Pseudomonas syringae type III secreted effector (T3SE) HopF1r and show that both HopF1r and Zaractin activate the same NLR-mediated immune pathway in Arabidopsis. Our results demonstrate that the ETIinducing action of pathogenic effectors can be harnessed to identify synthetic activators of the eukaryotic immune system. [ABSTRACT FROM AUTHOR]