From Head to Foot: Genetics of Wheat Seedling Resistance Against Root Rot Caused by Fusarium graminearum

As a consequence of the growing world population, global wheat production will be further intensified in the upcoming decades. This is accompanied by an increasing pressure of Fusarium diseases, such as head blight (FHB) or root rot (FRR). Fusarium graminearum (FG) is a well characterized wheat pathogen that is mainly known as the causal agent of FHB, one of the most important wheat diseases worldwide. Genetic studies to date have characterized over 220 QTL for FHB resistance, covering all 21 chromosomes. FRR has mainly been associated with F. culmorum or F. pseudograminearum, while the involvement of FG in below-ground plant infection remains largely unclear.

Here, we present the first large-scale genetic investigation of resistance towards FRR caused by FG. We phenotyped an extremely diverse collection of 215 international hexaploid wheat lines in a comprehensive greenhouse screen after root infection with fungal spores. In addition to the assessment of disease symptoms and biomass reduction of different plant parts, we quantified fungal spread in root and shoot tissues by RealTime-PCR. Using genome-wide genotyping data from the 90K Illumina Infinium SNP array, we identified conserved chromosome regions associated with increased resistance. Applying advanced quantitative genetics approaches we provide first interesting insights into the complex genetic architecture of resistance towards FRR caused by FG. Our findings provide a valuable basis for further molecular validations and genomics-assisted selection approaches to improve disease resistance in novel wheat varieties.