Evaluation of a Barley Core Collection for Spot Form Net Blotch Reaction Reveals Distinct Genotype-Specific Pathogen Virulence and Host Susceptibility

Abstract

Spot form net blotch (SFNB) caused by Pyrenophora teres f. maculata is a major foliar disease of barley (Hordeum vulgare) worldwide. SFNB epidemics have recently been observed in major barley producing countries, suggesting that the local barley cultivars are not resistant and that virulence of the local pathogen populations may have changed. Here we attempt to identify sources of resistance effective against four diverse isolates of P. teres f. maculata collected from around the world. A total of 2,062 world barley core collection accessions were phenotyped using isolates of the pathogen collected in the United States (FGO), Australia (SG1), New Zealand (NZKF2), and Denmark (DEN 2.6). Isolate-specific susceptibility was identified in several of the barley accessions tested, indicating variability in both pathogen virulence and host resistance/susceptibility. Collectively, only 15 barley accessions were resistant across all isolates tested. These resistant accessions will be used to generate mapping populations and for germplasm development. Future research will involve the characterization of host resistance, pathogen virulence, and the host-pathogen interaction associated with SFNB of barley.

Association Mapping of Seedling Resistance to Spot Form Net Blotch in a Worldwide Collection of Barley

“…A total of 2,062 spring BCC accessions were evaluated for their reaction to the four P. teres f. maculata isolates (FGO, NZKF2, SG1, and DEN 2.6) by Neupane et al (49). A total of 2,062 spring BCC accessions were evaluated for their reaction to the four P. teres f. maculata isolates (FGO, NZKF2, SG1, and DEN 2.6) by Neupane et al (49).…”

“…A total of 2,062 spring BCC accessions were evaluated for their reaction to the four P. teres f. maculata isolates (FGO, NZKF2, SG1, and DEN 2.6) by Neupane et al (49). Of the 2,062 accessions reported in Neupane et al (49), only 1,480 accessions were utilized in our analysis due to marker data not passing quality control and redundant genotypes being eliminated as determined by Muñoz-Amatriaín et al (46). Of the 2,062 accessions reported in Neupane et al (49), only 1,480 accessions were utilized in our analysis due to marker data not passing quality control and redundant genotypes being eliminated as determined by Muñoz-Amatriaín et al (46).…”

“…Fungal inoculum preparation, inoculation, and incubation used for the AM analyses described in this manuscript were performed and described in Neupane et al (49), which is published as an adjoining manuscript. Fungal inoculum preparation, inoculation, and incubation used for the AM analyses described in this manuscript were performed and described in Neupane et al (49), which is published as an adjoining manuscript.…”

“…Of the 2,417 barley accessions genotyped with the barley 9k Illumina Infinium iSELECT assay through the triticeae coordinated agriculture project (T-CAP), 2,062 of the barley accessions were evaluated for their reaction to the P. teres f maculata isolates (49). Of the 2,417 barley accessions genotyped with the barley 9k Illumina Infinium iSELECT assay through the triticeae coordinated agriculture project (T-CAP), 2,062 of the barley accessions were evaluated for their reaction to the P. teres f maculata isolates (49).…”

“…This pathogen is separated into the net and spot forms based on predominant disease symptoms with the causal agents being P. teres f. teres and P. teres f. maculata, respectively (57). However, since it was identified in North Dakota in 2006, it has become a major concern for growers in the Northern Great Plains due to what may be increased virulence as indicated by comparison with isolates collected in other parts of the world (49). Although SFNB had previously been reported in the Upper Midwestern United States, it was not considered a problem (34).…”