Evaluation of Oat Genotypes for Species-Specific and Cross-Resistance to Fusarium species and the role of trichomes in susceptibility

Selma Schurack¹Charlotte Rodemann²Klaus Oldach³Steffen Beuch⁴Sophie Brodführer⁵Andreas Von Tiedemann²Matthias Heinrich Herrmann^1*

• ¹Institute for Breeding Research on Agricultural Crops, Federal Research Center for Cultivated Plants, Julius Kühn Institute, Sanitz, Germany
• ²Plant Pathology and Crop Protection Division, Georg-August University Goettingen, Göttingen, Germany
• ³KWS LOCHOW GmbH, Bergen, Germany
• ⁴Nordsaat Saatzucht GmbH, Zuchtstation Granskevitz, Schaprode, Germany
• ⁵Saatzucht Bauer GmbH & Co. KG, Obertraubling, Germany

Resistance of oats to Fusarium head blight, caused by different Fusarium species, is important for grain quality and yield. In this study, 25 oat genotypes were evaluated for resistance to Fusarium graminearum (FG), F. sporotrichioides (FS) and F. poae (FP) in field trials across Germany to assess the presence of cross-resistance and analyse the role of trichomes on the hulls during Fusarium infection. Infection severity was quantified by Fusarium species-specific qPCR which showed the highest fungal biomass for FP, followed by FS and FG. Variability due to environmental effects was very high, resulting in rather low heritabilities for FG (0.50) and FS (0.36), and no significant genotype effect for FP. A significant positive correlation was found between FP and FS infection, whereas FG infection was not correlated with either FP or FS. Microscopic analyses revealed important genotype-specific differences in trichome size and density on lemma and palea with very high heritability (0.97). FG biomass was positively correlated with trichome size and density, and FG hyphae were observed in close interaction with trichomes and stomata. These results indicate the presence of partial cross-resistance for FS and FP in addition to mostly species-specific resistance and suggest a role for trichomes in susceptibility to FG.