Variability in chromosome 1 of select Moroccan P. teres f. teres isolates enables isolates to overcome a highly effective barley chromosome 6H source of resistance

Authors: LI, JINLING - North Dakota State University; Wyatt, Nathan; SKIBA, RYAN - Oak Ridge Institute For Science And Education (ORISE); KARIYAWASAN, GAYAN - North Dakota State University; RICHARDS, JONATHAN - Louisiana State University; EFFERTZ, KARL - Washington State University; REHMAN, SAJID - The International Center For Agricultural Research In The Dry Areas(ICARDA); BRUEGGEMANN, ROBERT - Washington State University; Friesen, Timothy

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2024
Publication Date: 6/18/2024
Citation: Li, J., Wyatt, N.A., Skiba, R., Kariyawasan, G., Richards, J., Effertz, K., Rehman, S., Brueggemann, R., Friesen, T.L. 2024. Variability in chromosome 1 of select Moroccan P. teres f. teres isolates enables isolates to overcome a highly effective barley chromosome 6H source of resistance. Molecular Plant-Microbe Interactions. https://doi.org/10.1094/MPMI-10-23-0159-R.
DOI: https://doi.org/10.1094/MPMI-10-23-0159-R

Interpretive Summary: Net form net blotch (NFNB), caused by the fungal pathogen Pyrenophora teres f. teres, is a destructive disease wherever barley is grown and is currently a major problem in malting barley production in the United States. Characterized NFNB resistance that is potentially useful in germplasm development is lacking. In this study, we genetically characterized the pathogen population to show that a single gene change is sufficient to overcome one of the most commonly used sources of NFNB resistance. This work shows that this valuable source of net blotch resistance must be integrated along with other sources of resistance if it is expected to maintain its effectiveness. This information will be useful in germplasm development and breeding for control of NFNB of barley.

Technical Abstract: Barley net form net blotch (NFNB) is a foliar disease caused by Pyrenophora teres f. teres. Barley line CIho5791 which harbors the chromosome 6H broad spectrum resistance gene Rpt1Rpt5, displays dominant resistance to P. teres f. teres. To genetically characterize P. teres f. teres avirulence/virulence on the barley line CIho5791, we generated a P. teres f. teres mapping population using a cross between the Moroccan CIho5791-virulent isolate MorSM40-3, and the reference avirulent isolate 0-1. Genetic maps were generated for all 12 chromosomes and quantitative trait locus (QTL) mapping identified two significant QTL associated with P. teres f. teres avirulence/virulence on CIho5791. The most significantly QTL with the highest association with disease mapped to P. teres f. teres Ch1 where the virulent allele was contributed by MorSM40-3. A second QTL mapped to Ch8, however, this virulence allele was contributed by 0-1. Additionally, the avirulence allele at the Ch1 locus was epistatic over the virulence allele at the Ch8 locus. The Ch1 and Ch8 loci accounted for 22.5 and 14.9% of the disease variation, respectively. Additionally, we used genome sequencing of 178 P. teres f. teres isolates to generate markers for a genome wide association study (GWAS) to identify two loci with significant marker-trait associations that were identified at the same Ch1 and Ch8 loci. Within the identified genomic regions, we found several genes that encoded secreted proteins, one or more of which may be responsible for overcoming the CIho5791 resistance. Results presented here demonstrate the complexity of virulence/avirulence involved in the P. teres f. teres –barley interaction.