A Putative Effector Pst-18220, from f. sp. , Participates in Rust Pathogenicity and Plant Defense Suppression.

Stripe rust, caused by f. sp. (), stands out as one of the most devastating epidemics impacting wheat production worldwide. Resistant wheat varieties had swiftly been overcome due to the emergence of new virulent strains. Effectors secreted by interfere with plant immunity, and verification of their biological function is extremely important for controlling wheat stripe rust. In this study, we identified an effector, Pst-18220, from f. sp. (), which was induced during the early infection stage of . Silencing the expression of Pst-18220 through virus-mediated host-induced gene silencing (HIGS) resulted in a decreased number of rust pustules. In , it significantly suppressed cell death induced by pv. () DC3000. In Arabidopsis, plants with stable overexpression of Pst-18220 showed increased susceptibility to DC3000, accompanied by a decrease in the expression level of pattern-triggered immunity (PTI)/effector-triggered immunity (ETI)-related genes, namely, AtPCRK1, AtPCRK2, and AtBIK1. These results emphasize the significant role of the candidate effector, -18220, in rust pathogenicity and the suppression of plant defense mechanisms. This broadens our understanding of effectors without any known motif.