Conserved effector families render Phytophthora species vulnerable to recognition by NLR receptors in nonhost plants

Abstract

Abstract NLR receptor is suggested as a component of plant nonhost resistance (NHR). However, the evolutionary process of how plants develop receptors for recognizing broad-spectrum pathogens is still elusive. Here, we observe that multiple RxLR effector families including 12 reported avirulence effectors of Phytophthora infestans are broadly conserved across the Phytophthora species. We select 69 effectors distributed into 8 families from 6 Phytophthora species, and confirm that 60.87% of the tested effectors are recognized by Solanum NLRs according to their defined families. Furthermore, we confirm that expression of R1, R8, and Rpi-amr1 confer broad-spectrum resistance against multiple Phytophthora species. Combined results suggest that conserved effector families of Phytophthora species allow solanaceous plants to recognize broad-spectrum pathogens via NLRs that originally reported to recognize P. infestans. Thus, NLR-mediated recognition would contribute to NHR against pathogens that possess similar repertoires of effectors. Moreover, this homology-based approach would be applicable to other plant-pathogen systems and provide an alternative strategy of genetic mapping to identify functional NLRs against various crop-threatening pathogens.