Wheat‐Rye T2BS·2BL‐2RL Recombinants with Resistance to Hessian Fly (H21)

Hessian fly, Mayetiola destructor (Say), is a destructive insect pest of common wheat (Triticum aestivum L.) and durum wheat (T. turgidum L.) worldwide. Although 32 genes conferring resistance to Hessian fly have been identified, only a few genes are still effective in North America. A highly effective gene is H21, transferred to wheat from Chaupon rye via a whole‐arm wheat‐rye translocation T2BS·2R#2L. This translocation also carries a gene for field resistance to powdery mildew. To broaden the use of T2BS·2R#2L in wheat improvement, we attempted to reduce the length of the rye segment by recombination with another wheat‐rye translocation T2BS·2BL‐2R#2L. Recombination data indicated that the H21 locus was linked to the telomere; the powdery mildew locus was closely linked to the translocation breakpoint in T2BS·2BL‐2R#2L. Recovered short‐segment rye translocation chromosomes confer resistance to Hessian fly; however, no crossover event in the desirable configuration was recovered to produce a short‐segment wheat‐rye translocation with both H21 and the powdery mildew resistance gene. The T2BS·2BL‐2R#2L recombinant chromosome was transferred to adapted winter and spring wheat cultivars.