Genome-wide association mapping of resistance to the foliar diseases septoria nodorum blotch and tan spot in a global winter wheat collection.

Unlabelled: Septoria nodorum blotch (SNB) and tan spot, caused by the necrotrophic fungal pathogens and , respectively, often occur together as a leaf spotting disease complex on wheat ( L.). Both pathogens produce necrotrophic effectors (NEs) that contribute to the development of disease. Here, genome-wide association analysis of a diverse panel of 264 winter wheat lines revealed novel loci on chromosomes 5A and 5B associated with sensitivity to the NEs SnTox3 and SnTox5 in addition to the known sensitivity genes for NEs Ptr/SnToxA, SnTox1, SnTox3, and SnTox5. Sensitivity loci for SnTox267 and Ptr ToxB were not detected. Evaluation of the panel with five isolates for SNB development indicated the -SnTox3 and -SnToxA interactions played significant roles in disease development along with additional QTL on chromosomes 2A and 2D, which may correspond to the -SnTox267 interaction. For tan spot, the -Ptr ToxC interaction was associated with disease caused by two isolates, and a novel QTL on chromosome 7D was associated with a third isolate. The -ToxA interaction was associated with SNB but not tan spot. Therefore some, but not all, of the previously characterized host gene-NE interactions in these pathosystems play significant roles in disease development in winter wheat. Based on these results, breeders should prioritize the selection of resistance alleles at the , , , and loci as well as the 2A and 7D QTL to obtain good levels of resistance to SNB and tan spot in winter wheat.

Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-023-01400-5.