Potato late blight caused by the notorious oomycete pathogen Phytophthora infestans led to the Irish famine in the 1840s.To date, this disease still remains a challenge for potato production (Figure 1).Effector proteins help P.infestans to infect their host plants, including potato and tomato.In summer 2004, in the Joint Genome Institute (Walnut Creek, California), some Phytophthora researchers gathered at an “Effector table,” and by aligning the amino acid sequences of many unpublished effector proteins from Phytophthora pathogens, revealed that all of them possess conserved Arg-any residue-Leu-Arg (RXLR)and Glu-Glu-Arg (EER) motifs post signal peptides (Govers and Gijzen, 2006).In 2009, the genome sequence of P.infestans strain T30-4 was published and 563 RXLR effectors were predicted.Since then, many high-throughput “effectoromics” screening strategies were carried out and effectors were identified that trigger a hypersensitive response (HR) on some host genotypes, or that function as cell death repressors or RNA silencing suppressors.However, the function of most RXLR effectors remains unknown.