The cloning and characterization of the AvrLr41 effector gene

Abstract

The rust fungi (stem, stripe, and leaf rust) of the genus Puccinia are the most damaging and feared threat to wheat production. Leaf rust, caused by Puccinia triticina (Pt), alone can cause more than 20% yield losses (Figueroa et al., 2018). Pt is an obligate biotroph that survives and replicates only in live host tissues. The pathogen delivers effectors into wheat cells during infection. AvrLr41 is a Pt effector recognized by the wheat leaf rust resistance (Lr) gene Lr41, triggering defense responses, including programmed cell death or hypersensitive response (HR) surrounding the infection sites. One candidate of AvrLr41 has been identified based on the polymorphism between the Pt races that can or cannot trigger Lr41-mediated HR. Using three assays, we validate that the candidate gene is AvrLr41 and that domain three of the AvrLr41 protein is required to induce Lr41-mediated HR in wheat. AvrLr41 was verified to interact with Lr41 and one domain was found to be toxic when alone. Bioinformatic analysis indicated that AvrLr41 is a highly uncharacterized protein with no conserved domains. Advances in understanding leaf rust resistance genes and their interacting partners can be used to develop new resistance genes with pleiotropic resistance to rust pathogens.