Abstract
Powdery mildew (PM) is a very destructive disease of wheat (Triticum aestivum L.). Wheat-Thinopyrum ponticum introgression line CH7086 was shown to possess powdery mildew resistance possibly originating from Th. ponticum. Genomic in situ hybridization and molecular characterization of the alien introgression failed to identify alien chromatin. To study the genetics of resistance, CH7086 was crossed with susceptible genotypes. Segregation in F2 populations and F2:3 lines tested with Chinese Bgt race E09 under controlled conditions indicated that CH7086 carries a single dominant gene for powdery mildew resistance. Fourteen SSR and EST-PCR markers linked with the locus were identified. The genetic distances between the locus and the two flanking markers were 1.5 and 3.2 cM, respectively. Based on the locations of the markers by nullisomic-tetrasomic and deletion lines of ‘Chinese Spring’, the resistance gene was located in deletion bin 2BL-0.89-1.00. Conserved orthologous marker analysis indicated that the genomic region flanking the resistance gene has a high level of collinearity to that of rice chromosome 4 and Brachypodium chromosome 5. Both resistance specificities and tests of allelism suggested the resistance gene in CH7086 was different from previously reported powdery mildew resistance genes on 2BL, and the gene was provisionally designated PmCH86. Molecular analysis of PmCH86 compared with other genes for resistance to Bgt in the 2BL-0.89-1.00 region suggested that PmCH86 may be a new PM resistance gene, and it was therefore designated as Pm51. The closely linked flanking markers could be useful in exploiting this putative wheat-Thinopyrum translocation line for rapid transfer of Pm51 to wheat breeding programs.
Highlights
Powdery mildew (PM), caused by Blumeria graminis f. sp. tritici (Bgt), is a globally important disease of wheat (Triticum aestivum L.)
These results demonstrated that CH7086 was resistant to powdery mildew, with the infection types (ITs) being similar to the donor Xiaoyan 7430 (IT 0-0;) as well as the donor Th. ponticum accession R431 (IT 0)
When GISH using Th. ponticum genomic DNA as probe was performed on the wheat-Th. ponticum partial amphiploid Xiaoyan 7430 (2n556) and line CH7086, 14 Th. ponticum chromosomes were clearly distinguishable in the mitotic metaphases of Xiaoyan 7034
Summary
Powdery mildew (PM), caused by Blumeria graminis f. sp. tritici (Bgt), is a globally important disease of wheat (Triticum aestivum L.). Tritici (Bgt), is a globally important disease of wheat (Triticum aestivum L.). Resistant varieties are the most feasible means of controlling the disease and reducing yield losses. 54 formally designated Pm resistance genes have been identified. They have been mapped to 46 loci and assigned to specific chromosomes or chromosome arms [1]. Of these loci, 29 genes were transferred from relatives, including T. turgidum var. New sources of effective and durable resistance from both common wheat and wild relatives are required for resistance breeding
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