High-Resolution Mapping and Candidate Gene Identification of Unique Pyrenophora teres f. teres Necrotrophic Effector Host Sensitivities on Barley Chromosome 6H
J. RICHARDS (1), T. Friesen (2), R. Brueggeman (1) (1) North Dakota State University, U.S.A.; (2) USDA-ARS, Cereal Crops Research Unit, Red River Valley Agricultural Research Center, U.S.A.

Pyrenophora teres f. teres (Ptt), a necrotrophic fungal pathogen, is the causal agent of the economically important disease net form net blotch of barley and resistance/susceptibility has often mapped to a common locus on chromosome 6H. Dominant susceptibility to Ptt isolates 6A and 15A, existing in repulsion, was identified at the 6H locus in barley cvs. Rika and Kombar, respectively. Additionally, a previous study identified four unique virulence QTL in a 15A x 6A population, two from each isolate. Utilizing a high-resolution mapping population consisting of 2976 recombinant gametes derived from a Rika x Kombar cross and genetic markers designed from barley orthologs of Brachypodium distachyon genes, dominant susceptibility to isolates 15A, 6A, and three progeny isolates containing single virulence loci mapped to a single  ~0.24 cM region, designated the Spt1 locus. This region corresponds to ~9.5 Mb of physical sequence and contains 49 predicted barley genes, including six predicted immunity receptor-like genes. A candidate LRR receptor-like gene, Spt1.cg, was identified and three diverged alleles have been sequenced from cvs. Rika, Kombar, and Morex. Allele analysis of diverse barley lines exhibits a direct correlation with the presence of a Rika, Kombar, or Morex Spt1.cg allele and susceptibility to P. teres f. teres isolates 6A, 15A, and TA5/TD10. Validation is currently underway through post-transcriptional gene silencing and high-resolution association analysis.

Abstract Number: P17-597
Session Type: Poster