Characterization of PmBN418, a wheat powdery mildew resistance gene on the rye 1RS chromosome arm

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a disease of global importance, and new powdery mildew resistance genes that can be directly used in cultivar development are urgently needed. A recombinant inbred line population from 'CI 17884' x 'Bainong 418' was genotyped using single nucleotide polymorphism markers generated from genotyping-by-sequencing, and evaluated for responses to Great Plains Bgt isolates OKS(14)-B-3-1 and NEI-1-3. Genetic mapping identified a powdery mildew resistance gene, designated PmBN418, on a 1BL.1RS translocation segment in Bainong 418. Given that PmBN418 conferred resistance to Bgt isolates virulent to Pm8 that resides on the chromosome arm 1RS translocated from rye (Secale cereale L.) cv. 'Petkus', PmBN418 is either a new gene or a new allele of Pm8. Phenotypic and genomic data analyses indicated segregation distortion of the powdery mildew resistance gene due to reduced transmission of the wheat (Triticum aestivum L.)-rye 1BL.1RS translocation segment from Bainong 418, while the wheat-Triticum speltoides translocation segment 7S#1 in CI 17884 was preferentially transmitted. Bainong 418, a high-yielding cultivar with good resistance to several U.S. Bgt isolates, is a useful resistance source for wheat breeding, and the availability of the Kompetitive Allele Specific PCR (KASP) marker KASP-1RS-1 makes marker-assisted introgression of PmBN418 into locally adapted cultivars feasible.

Automated summary

A new powdery mildew resistance gene, PmBN418, was identified on a 1BL.1RS translocation segment in Bainong 418, potentially offering a valuable resource for wheat breeding. Distorted segregation and preferential transmission of translocation segments were observed in Bainong 418 and CI 17884, highlighting the importance of marker-assisted introgression for incorporating PmBN418 into locally adapted wheat cultivars.