Population genomics uncovers the Verticillium dahliae effector that is recognized by the tomato Ve1 immune receptor

PL5.1 Population genomics uncovers the Verticillium dahliae effector that is recognized by the tomato Ve1 immune receptor Bart P.H.J. Thomma Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands Cell surface receptors, generally referred to as pattern recognition receptors (PRR), detect conserved microbial molecules, generally referred to as microbe-associated molecular patterns (MAMPs), to activate MAMP-triggered immunity (MTI). Successful plant pathogens overcome MTI by the use of secreted effectors which perturb host immunity in a pro-active manner. An example is provided by LysM effectors that are secreted by various fungal plant pathogens during infection to sequester fungal cell wall-derived MAMPs to prevent detection by the host and activation of MAMP-triggered immunity. To overcome effector-triggered susceptibility, plants in turn evolved immune receptors that monitor the presence or activity of particular effectors to re-install immunity. The tomato immune receptor Ve1 governs resistance to race 1 strains of the soil-borne vascular wilt fungus Verticillium, while race 2 strains are not recognized. Thus far, the Verticillium effector that is monitored by Ve1 remained unknown. By high-throughput population genome sequencing, we identified a sequence stretch that only occurs in race 1 strains, and that is absent from race 2 strains. Within this region the Ave1 (for Avirulence on Ve1 tomato) gene was identified. Functional analyses confirmed that Ave1 activates Ve1-mediated resistance and demonstrated that Ave1 contributes to fungal virulence. Interestingly, Ave1 is homologous to a widespread family of plant proteins. Besides plants, homologous proteins were also found in few plant pathogenic fungi, including the fungal pathogens Colletotrichum higginsianum and Fusarium oxysporum f. sp. lycopersici. Remarkably, some of these Ave1 homologs can activate Ve1-mediated resistance in tomato as well.