Genetics of Leaf Rust Resistance in Canadian Spring Wheats AC Domain and AC Taber

The hard red spring wheat cultivar AC Domain and the Canada Prairie Spring wheat AC Taber have recently been licensed and released in western Canada and are resistant to leaf rust caused by Puccinia recondita f. sp. tritici. To determine the genetic basis of this resistance, the two cultivars were crossed with the leaf rust susceptible wheat Thatcher (Tc), and F₁ plants were backcrossed to Thatcher. F₂ families from Tc*2/AC Domain and AC Taber/Tc*2 were tested with isolates of P. recondita f. sp. tritici as seedlings in the greenhouse and as adults in the field rust nursery. Segregation of BC₁F₂ families indicated that AC Domain had seedling resistance genes Lr10 and Lr16, and the adult plant gene Lr34. AC Domain was also hypothesized to have the adult plant gene Lr12 based on infection types with P. recondita f. sp. tritici isolates that differed for virulence to Lr12. The effective field leaf rust resistance of AC Domain was conditioned by Lr16 and Lr34. Segregation of BC₁F₂ families and infection types of BC₁F₃-derived BC₁F₄ plants indicated that AC Taber had Lr14a for seedling resistance, the adult plant gene Lr13, plus an additional uncharacterized adult plant resistance gene currently designated as LrTb.