islamov@ipk-gatersleben.de

marina.tikhonova@metk.agri.ee

Wheat is the most widely grown crop in the Baltic Sea Region. Although wheat production has seen a significant increase in recent years, thanks to the availability of locally adapted varieties and enhanced agricultural practices, it still faces challenges from adverse weather conditions and disease pressure. Powdery mildew is a major biotrophic plant pathogen that significantly impacts wheat production in the region.

However, the deployment of resistance gene combinations effective at different developmental stages using marker selection can help control the disease. In this study we evaluated seedling and adult plant resistance of wheat germplasm and tested the applicability of marker selection. We used 55 spring and winter wheat varieties widely grown in the region as well as wheat lines with known resistance genes as controls to be challenged by a diverse collection of European powdery mildew isolates. We hypothesised that seedling resistance to a wide spectrum of isolates could predict resistance observed in the field.

We postulated the presence of common resistance genes by comparing seedling resistance patterns of wheat varieties with those of control lines, for which resistance genes are already described. The existence of shared resistance genes was further confirmed by using specific DNA markers to Pm1a, Pm3 and Pm6. In addition, we screened the material for adult plant resistance genes and visually assessed disease severity in the field.

According to seedling resistance data, Pm1a, Pm3d and Pm6 are only partially effective against the local powdery mildew population and the protective effect can be increased by combination of two or more Pm genes. Powdery mildew severity data on adult plants in the field experiment confirmed our hypothesis that broad spectrum seedling resistance is also effective in adult plants.

Even though wheat varieties with a broader spectrum of seedling resistance exhibited lower disease severity in the field, a small portion of varieties lacking seedling resistance also showed lower disease severity compared to the control lines. This can be explained by the presence of yet undescribed adult plant resistance genes in these lines.

Identification of seedling resistance to multiple isolates combined with disease severity data obtained from the field trial and DNA marker analysis can aid selection for powdery mildew resistance.