|RICHARDS, JONATHAN - North Dakota State University|
|BRUEGGEMAN, ROBERT - North Dakota State University|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2017
Publication Date: 2/9/2017
Publication URL: http://handle.nal.usda.gov/10113/5700689
Citation: Richards, J.K., Friesen, T.L., Brueggeman, R.S. 2017. Association mapping utilizing diverse barley lines reveals net form net blotch seedling resistance/susceptibility loci. Theoretical and Applied Genetics. 130:915-927. doi:10.1007/s00122-017-2860-1.
Interpretive Summary: Pyrenophora teres f. teres is a fungal pathogen and the causal agent of the economically important foliar disease net form net blotch (NFNB) of barley. The deployment of effective and durable resistance against P. teres f. teres has been hindered by the complexity of quantitative resistance and susceptibility. A diverse collection of barley lines was phenotyped with three North American Pyrenophora teres f. teres isolates and association analyses detected 78 significant marker-trait associations at 16 genomic loci.
Technical Abstract: Pyrenophora teres f. teres is a necrotrophic fungal pathogen and the causal agent of the economically important foliar disease net form net blotch (NFNB) of barley. The deployment of effective and durable resistance against P. teres f. teres has been hindered by the complexity of quantitative resistance and susceptibility. Several bi-parental mapping populations have been used to identify QTL associated with NFNB disease on all seven barley chromosomes. Here, we report the first genome-wide association study (GWAS) to detect marker-trait associations for resistance or susceptibility to P. teres f. teres. Geographically diverse barley genotypes from a world barley core collection (957) were genotyped with the Illumina barley iSelect chip and phenotyped with three P. teres f. teres isolates collected in two geographical regions of the USA (15A, 6A and LDNH04Ptt19). The best of nine regression models tested were identified for each isolate and used for association analysis resulting in the identification of 78 significant marker-trait associations (MTA; -log10p value'>3.0). The MTA identified corresponded to 16 unique genomic loci as determined by analysis of local linkage disequilibrium between markers that did not meet a correlation threshold of R2'='0.1, indicating that the markers represented distinct loci. Five loci identified represent novel QTL and were designated QRptts-3HL, QRptts-4HS, QRptts-5HL.1, QRptts-5HL.2, and QRptts-7HL.1. In addition, 55 of the barley lines examined exhibited a high level of resistance to all three isolates and the SNP markers identified will provide useful genetic resources for barley breeding programs.