A small secreted protein in Zymoseptoria tritici is responsible for avirulence on wheat cultivars carrying the Stb6 resistance gene.
Zymoseptoria tritici is the causal agent of Septoria tritici blotch, a major pathogen of wheat globally and the most damaging pathogen of wheat in Europe. A gene-for-gene (GFG) interaction between Z. tritici and wheat cultivars carrying the Stb6 resistance gene has been postulated for many years, but the genes have not been identified. We identified AvrStb6 by combining quantitative trait locus mapping in a cross between two Swiss strains with a genome-wide association study using a natural population of c. 100 strains from France. We functionally validated AvrStb6 using ectopic transformations. AvrStb6 encodes a small, cysteine-rich, secreted protein that produces an avirulence phenotype on wheat cultivars carrying the Stb6 resistance gene. We found 16 nonsynonymous single nucleotide polymorphisms among the tested strains, indicating that AvrStb6 is evolving very rapidly. AvrStb6 is located in a highly polymorphic subtelomeric region and is surrounded by transposable elements, which may facilitate its rapid evolution to overcome Stb6 resistance. AvrStb6 is the first avirulence gene to be functionally validated in Z. tritici, contributing to our understanding of avirulence in apoplastic pathogens and the mechanisms underlying GFG interactions between Z. tritici and wheat.
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.
Ziming
Z
Zhong
UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France.
Thierry C
TC
Marcel
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.
Fanny E
FE
Hartmann
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.
Xin
X
Ma
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.|UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France.
Clémence
C
Plissonneau
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.
Marcello
M
Zala
UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France.
Aurélie
A
Ducasse
UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France.
Johann
J
Confais
UR URGI, INRA, Université Paris-Saclay, 78026, Versailles, France.
Jérôme
J
Compain
UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France.|UR URGI, INRA, Université Paris-Saclay, 78026, Versailles, France.
Nicolas
N
Lapalu
UR URGI, INRA, Université Paris-Saclay, 78026, Versailles, France.
Joëlle
J
Amselem
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.
Bruce A
BA
McDonald
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.|Laboratory of Evolutionary Genetics, University of Neuchâtel Institute of Biology Rue Emile-Argand 11, CH-2000, Neuchâtel, Switzerland.
Daniel
D
Croll
Plant Pathology Group, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland.
Javier
J
Palma-Guerrero
D000595:Amino Acid Sequence; D001203:Ascomycota / Q000472:pathogenicity*; D001483:Base Sequence; D002874:Chromosome Mapping; D060467:Disease Resistance / Q000235:genetics*; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D017343:Genes, Plant; D055106:Genome-Wide Association Study; D015810:Linkage Disequilibrium / Q000235:genetics; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011110:Polymorphism, Genetic; D040641:Quantitative Trait Loci / Q000235:genetics; D014908:Triticum / Q000235:genetics* / Q000382:microbiology*; D014774:Virulence / Q000235:genetics
D005656:Fungal Proteins; D010940:Plant Proteins

AvrStb6
; 
Stb6
; 
Zymoseptoria tritici
; avirulence; gene-for-gene interaction; genome-wide association study (GWAS); quantitative trait locus (QTL) mapping