Analysing and harnessing genetic resources for organic winter barley breeding with a focus on resistance to loose smut (Ustilago nuda).

Loose smut of barley (Hordeum vulgare) caused by the fungal pathogen Ustilago nuda is a resurgent seed-borne disease with devastating effects on seed quality and yield. Effective control strategies are mainly based on plant protection with synthetic fungicides, which cannot be used under organic production rules. Therefore, the most economical and environmentally friendly option is to breed resistant varieties.
The aim of the “Flugbrand-Resist” project is to gain a better understanding of resistance to loose smut in barley and to increase resistance in winter barley. To this end, several hundred genotypes of different origins, together with mostly older elite lines, will be screened for resistance parameters after artificial inoculation. Different pathogen isolates of European origin will be tested to evaluate the aggressiveness and virulence pattern using a differential set of barley with known resistance genes. All phenotypically evaluated barley lines will be genotyped using recent single nucleotide polymorphism (SNP) arrays and genome-wide association studies (GWAS) will be performed to identify QTL associated with loose smut resistance. Based on the results, a bi-parental populations will be established by crossing resistant donor lines with non-resistant genotypes. These populations will be used for fine mapping of loose smut resistance loci and for inferring closely linked molecular markers.
As a result, this project aims to facilitate the breeding of new loose smut resistant winter barley cultivars with improved resistance and to ensure sustainable cultivation without the use of synthetic chemicals. It will also support organic farming and environmentally friendly disease control to meet the criteria of the European Green Deal and the EU's Farm to Fork strategy. The project is a collaboration between KWS Saat SE, organic breeding institute Research & Breeding Dottenfelderhof and the Julius Kühn Institute.