Wheat resistance to Fusarium head blight

Fusarium head blight (FHB), caused primarily by Fusarium graminearum, has rapidly become the most devastating wheat disease worldwide. Host resistance is the most effective and sustainable strategy to combat the disease. To date, more than 50 unique quantitative trait loci (QTLs) have been identified in diverse wheat populations, and Fhb1 consistently shows the highest level of resistance in different genetic backgrounds. In spite of worldwide efforts to deploy Fhb1 through wheat breeding, only a few cultivars currently used in commercial production carry Fhb1. Recently, Fhb1 has been cloned and diagnostic markers have been developed, which will facilitate successful deployment of Fhb1 in wheat breeding. Using marker-assisted backcross, Fhb1 has been successfully transferred into locally adapted cultivars that carry minor QTLs, and selected Fhb1 lines in different backgrounds showed high levels of FHB resistance. This approach may provide a quick solution to improvement of FHB resistance in commercial cultivars. In addition, gene editing that knocks down the susceptible allele of Fhb1 in commercial cultivars may also improve wheat FHB resistance. Most other QTLs identified to date show much smaller effects than Fhb1. These QTLs are distributed in many locally adapted cultivars, and thus are important QTLs for FHB resistance improvement. Currently, diagnostic markers are still not available for most of these minor QTLs; therefore, genomic selection may improve selection accuracy for these QTLs to create highly FHB-resistant cultivars.