The wheat Stb6 gene controlling a gene-for-gene resistance to Zymoseptoria tritici encodes a wall-associated kinase like protein
C. SAINTENAC (1), W. Lee (2), F. Cambon (1), J. Rudd (2), R. King (2), A. Phillips (2), C. Uauy (3), K. Hammond-Kosack (2), T. Langin (1), K. Kanyuka (2) (1) INRA, and Université Blaise Pascal, France; (2) Rothamsted Research, United Kingdom; (3) John Innes Centre, United Kingdom

Z. tritici is an ascomycete fungus that causes Septoria tritici blotch (STB), a globally economically damaging foliar disease of wheat. Resistance to STB is an important target in wheat breeding and during the past several decades at least 18 major resistance loci, most of which confer an isolate-specific resistance, have been identified and genetically mapped. However, none of these have so far been cloned. Stb6 is the most well characterised resistance gene that controls Z. tritici isolates carrying a matching avirulence gene AvrStb6 via an unknown mechanism not involving HR. Here we report isolation of Stb6 using a combination of map-based cloning, VIGS, TILLING and stable wheat transformation. We show that Stb6 encodes a trans-membrane protein with an extracellular galacturonan-binding domain and a cytoplasmic kinase domain, and thus is a member of the wall-associated receptor kinase (WAK) gene family. This finding is in line with Z. tritici being a pathogen that colonises leaf apoplast and does not penetrate host plant cells or develop appressoria. We also show that the common disease susceptibility alleles contain non-synonymous mutations corresponding to changes at the conserved amino acid residues in the kinase domain of the encoded protein, suggesting a mechanism of susceptibility which involves a loss of kinase activity. To our knowledge, this is the first report demonstrating control of gene-for-gene resistance by a WAK-like protein in plants.

Abstract Number: C18-4, P15-434
Session Type: Concurrent