Mutagenesis of Wheat Powdery Mildew Reveals a Single Gene Controlling Both NLR and Tandem Kinase-Mediated Immunity.

f. sp. () is a globally important fungal wheat pathogen. Some wheat genotypes contain powdery mildew resistance () genes encoding immune receptors that recognize specific fungal-secreted effector proteins, defined as avirulence (Avr) factors. Identifying Avr factors is vital for understanding the mechanisms, functioning, and durability of wheat resistance. Here, we present AvrXpose, an approach to identify genes in by generating gain-of-virulence mutants on genes. We first identified six mutants with gain of virulence on and They all had point mutations, deletions or insertions of transposable elements within the corresponding gene or its promoter region. We further selected six mutants on , aiming to identify the yet unknown AvrPm3 recognized by Pm3a, in addition to the previously described AvrPm3. Surprisingly, virulence in the obtained mutants was always accompanied by an additional gain of virulence on the unrelated tandem kinase resistance gene No virulence toward 11 additional genes tested was observed, indicating that the gain of virulence was specific for and . Several independently obtained mutants have mutations in , a gene encoding a putative, nonsecreted ankyrin repeat-containing protein. Gene expression analysis suggests that regulates a subset of effector genes. We conclude that is a common factor required for avirulence on both a specific nucleotide-binding leucine-rich repeat and a WTK immune receptor. Our findings suggest that, beyond effectors, another type of pathogen protein can control the race-specific interaction between powdery mildew and wheat. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.