Evaluation of disease resistance in intermediate wheatgrass and genome-wide association for fusarium head blight-related traits

Abstract

Intermediate wheatgrass (IWG) [Thinopyrum intermedium (Host) Barkworth & D. R. Dewey] is a promising perennial grain candidate that The Land Institute has been directly domesticating since 2001. Grain from improved IWG can be sold under the trademark Kernza. Resistance to Fusarium head blight (FHB) is a high priority trait to reduce toxin content of the grain and protect the value and seed supply of Kernza. We evaluated two breeding cycles of IWG from 2018 to 2022 with each cycle containing ∼500 unique genets to investigate disease response and identify chromosomal regions associated with disease resistance. Quantitative trait loci were mapped for 17 different traits using 32,067 markers in 21 linkage groups with genome-wide association analysis. A total of 188 unique marker-trait associations were detected across 14 different traits with five of these traits related to FHB resistance. We additionally used the basic local alignment search tool alignment creation tool to identify homologies between the Fhb1 region of wheat and the IWG genome, including an IWG GDSL-like lipase/Acylhydrolase gene (Thintv31194873.m.g) with similarity (query = 89%) to the Triticum aestivum Sumai 3 Fhb1 genomic sequence. Other candidate genes outside of the Fhb1 region were identified for Fusarium resistance with functions associated with toxin reduction and defense hormones and metabolites. These results provide loci that could be used in future selections to improve IWG's genetic resistance to FHB.