TdPm60 identified in wild emmer wheat is an ortholog of Pm60 and constitutes a strong candidate for PmG16 powdery mildew resistance

Key message We identified TdPm60 alleles from wild emmer wheat (WEW), an ortholog of Pm60 from T. urartu, which constitutes a strong candidate for PmG16 mildew resistance. Deployment of PmG16 in Israeli modern bread wheat cultivar Ruta improved the resistance to several local Bgt isolates. Wild emmer wheat (WEW), the tetraploid progenitor of durum and bread wheat, is a valuable genetic resource for resistance to powdery mildew fungal disease caused by Blumeria graminis f. sp. tritici (Bgt). PmG16 gene, derived from WEW, confers high resistance to most tested Bgt isolates. We mapped PmG16 to a 1.4-cM interval between the flanking markers uhw386 and uhw390 on Chromosome 7AL. Based on gene annotation of WEW reference genome Zavitan_V1, 34 predicted genes were identified within the -3.48-Mb target region. Six genes were annotated as associated with disease resistance, of which TRIDC7AG077150.1 was found to be highly similar to Pm60, previously cloned from Triticum urartu, and resides in the same syntenic region. The functional molecular marker (FMM) for Pm60 (M-Pm60-S1) co-segregated with PmG16, suggesting the Pm60 ortholog from WEW (designated here as TdPm60) as a strong candidate for PmG16. Sequence alignment identified only eight SNPs that differentiate between TdPm60 and TuPm60. Furthermore, TdPm60 was found to be present also in the WEW donor lines of the powdery mildew resistance genes MUW/ 72 and MlIW72, mapped to the same region of Chromosome 7AL as PmG16, suggesting that TdPm60 constitutes a candidate also for these genes. Furthermore, screening of additional 230 WEW accessions with Pm60 specific markers revealed 58 resistant accessions from the Southern Levant that harbored TdPm60, while none of the susceptible accessions showed the presence of this gene. Deployment of PmG16 in Israeli modern bread wheat cultivar Ruta conferred resistance against several local Bgt isolates.

Automated summary

This study identified the TdPm60 alleles from wild emmer wheat as a strong candidate for PmG16 mildew resistance, which showed improved resistance in Israeli modern bread wheat. The findings suggest that TdPm60 could also be a candidate for other powdery mildew resistance genes.