Wheatgrass–Wheat Partial Amphiploids as a Novel Source of Stem Rust and Fusarium Head Blight Resistance

Perennial wheatgrasses ( Thinopyrum spp.) are recognized sources of genetic variation for annual wheat ( Triticum aestivum L.) improvement. Amphiploid lines made by crossing Thinopyrum spp. and T. aestivum (common wheat) can increase resilience of wheat to pathogens and abiotic stress. However, lack of pairing between chromosomes of Thinopyrum and Triticum species reduces genome stability, seed set, and perenniality. Fifty‐two wheat–wheatgrass amphiploids from the perennials Thinopyrum intermedium (Host) Barkworth & D. R. Dewey, Thinopyrum ponticum (Podp.) Barkworth & D. R. Dewey, and Thinopyrum junceum (L.) Á. Löve crossed with the annuals T. aestivum , Triticum turgidum L. subsp. carthlicum (Nevski) Á. Löve & D. Löve (syn. Triticum carthlicum Nevski), and Triticum turgidum subsp. durum (Desf.) Husn , were screened for wheat stem rust (caused by Puccinia graminis ) and Fusarium head blight (FHB) (caused by Fusarium graminearum ) reaction and evaluated for winter hardiness and perenniality. Twenty‐four of 48 amphiploid lines were resistant to all stem rust races screened, including TTKSK (syn. Ug99), TRTTF, and common U.S. races. Of the 30 amphiploid lines point inoculated with F. graminearum , 21 were resistant based on the percentage of infected spikelets and the percent of visually scabby kernels. Three sources each of potentially novel stem rust and uncharacterized FHB resistance were identified and may be useful for wheat improvement. Two lines showed perenniality in Minnesota and may be valuable as cold‐tolerant perennial wheat germplasm. Seven lines representing two families showed potential genetic stability based on chromosome counts and seed production.