# Validation of markers for resistance to Pyrenophora teres f. teres loci on barley chromosomes 3H, 4H, and 6H in the polygenic inheritance of the trait

## TL;DR

This study identifies and validates genetic markers linked to resistance against a barley disease caused by Pyrenophora teres f. teres, supporting marker-assisted breeding.

## Contribution

The study validates specific SNP markers on barley chromosomes 3H, 4H, and 6H associated with resistance to Pyrenophora teres f. teres.

## Key findings

- CAPS marker JHI-Hv50k-2016-391380 on chromosome 6H showed significant association with resistance in F2 plants from four crosses.
- Markers on chromosome 4H (JHI-Hv50k-2016-237924 and SCRI_RS_181886) were significantly linked to resistance in specific crosses.
- A QTL on chromosome 6H masks other resistance genes, explaining discrepancies between phenotypes and marker presence.

## Abstract

The causal agent of net blotch Pyrenophora teres Drechs. f. teres (Ptt) is a dangerous pathogen of barley. The development of genetic protection against this disease is a necessary link in resource-saving and environmentally friendly barley cultivation technologies. Effective QTL markers controlling both qualitative and quantitative resistance are required for breeding for resistance to Ptt. As a result of GWAS, we identified barley accessions of different origins, the SNP haplotypes of which were associated with resistance loci simultaneously on different barley chromosomes (VIR catalogue numbers: k-5900, k-8829, k-8877, k-14936, k-30341 and k-18552). The aim of the study was to validate SNP markers (MM) of Ptt resistance loci on chromosomes 3H, 4H and 6H in F2 from crossing six resistant accessions with the susceptible variety Tatum. The observed segregation for resistance in all crossing combinations confirmed the presence of several genetic determinants of resistance in the studied accessions. To study the polymorphism of the parents from the crosses and the correspondence between the phenotypes to the presence/absence of the markers in the segregating populations, primers with a specific 3’-end, CAPS markers, and KASP markers were developed. A significant association (p < 0.05) between the presence of the CAPS marker JHI-Hv50k-2016-391380 HindIII on chromosome 6H and the phenotype of resistance to Ptt in F2 plants was revealed in crosses between the susceptible cultivar Tatum and accessions k-5900, k-8829, k-8877 and k-18552. On chromosome 4H, a significant association with the resistance phenotype in the F2 population from the cross with accession k-8877 was revealed for marker JHI-Hv50k-2016-237924, and in that from the cross with accession k-5900, for marker SCRI_RS_181886. The presence of QTL on chromosome 6H, which controls qualitative resistance in four barley accessions, masks the expression of other genes, which explains the discrepancy between the resistance phenotype and the presence of molecular markers in the segregating populations. Resistance donors and molecular markers with proven efficacy can be used in marker-assisted selection (MAS) to develop barley cultivars resistant to net blotch