Genetic and physical localization of a major susceptibility gene to Pyrenophora teres f. maculata in barley

Authors: ALHASHEL, ABDULLAH - North Dakota State University; Fiedler, Jason; Nandety, Raja Sekhar; SKIBA, RYAN - Oak Ridge Institute For Science And Education (ORISE); BRUGGEMAN, ROBERT - Washington State University; BALDWIN, THOMAS - North Dakota State University; Friesen, Timothy; Yang, Shengming

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2023
Publication Date: 4/27/2023
Citation: Alhashel, A., Fiedler, J.D., Nandety, R., Skiba, R., Bruggeman, R., Baldwin, T., Friesen, T.L., Yang, S. 2023. Genetic and physical localization of a major susceptibility gene to Pyrenophora teres f. maculata in barley. Theoretical and Applied Genetics. 136. Article e118. https://doi.org/10.1007/s00122-023-04367-1.
DOI: https://doi.org/10.1007/s00122-023-04367-1

Interpretive Summary: A fungal disease known as spot-form net blotch, or SFNB, occurs worldwide and can cause significant yield losses in barley. Understanding the genetic mechanisms involved in governing resistance and susceptibility of barley plants to SFNB would aid researchers in developing barley varieties that better resist the disease. In this study, we conducted genetic analysis of resistant and susceptible barley lines to determine more precisely the genomic location of a specific barley gene that, when present, renders the barley plant susceptible to the disease. This gene, referred to as Sptm1, was located to a small segment of a specific barley chromosome. Further analysis of the segment indicated that it harbors a gene known as a protein kinase, which are typically associated with disease resistance or susceptibility in plants. Therefore, the protein kinase gene may be a focus of future research to discover the identity of the Sptm1 gene. We also developed molecular markers that can be used to track the presence of the gene when developing new barley varieties. The results of this research provide a foundation for geneticists to advance our knowledge of how barley plants interact with the pathogen that causes SFNB and provides tools for breeders to develop SFNB-resistant barley varieties.

Technical Abstract: Spot form net blotch (SFNB), caused by the necrotrophic fungal pathogen Pyrenophora teres f. maculata (Ptm), is one of the important foliar diseases in barley. Although various resistance loci have been identified, breeding for SFNB-resistant varieties has been hampered due to the complex virulence profile of Ptm populations. One resistance locus in the host may be effective against one specific isolate, but it may be susceptible to other isolates. However, a major susceptibility QTL on chromosome 7H, named Sptm1, was consistently identified in many studies. To fine map towards cloning of the Sptm1 gene, we conducted genetic mapping in the present study. A segregating population was developed from selected F2 progenies of the cross Tradition (S) x PI 67381 (R), in which the disease phenotype was determined by the Sptm1 locus alone. Disease phenotypes of critical recombinants were confirmed in the following two consecutive generations. Genetic mapping anchored the Sptm1 gene to an '400 kb region on 7H. Gene prediction and annotation identified six protein-coding genes in the Sptm1 locus, and the gene encoding a putative cold responsive protein kinase was selected as a strong candidate. Therefore, providing fine localization and candidate of Sptm1 for functional validation, our study will facilitate the understanding of susceptibility mechanism underlying the Ptm-barley interaction and offers a potential target for gene editing to develop valuable material with broad-spectrum resistance to SFNB.