Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic. Wheat landraces are important resources of resistance to many diseases. Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance. The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew. To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F₁, BC₁, F₂, and F_2:3 were tested with Bgt isolate E09. The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT. An Illumina wheat 90K single-nucleotide polymorphism (SNP) array was applied to screen polymorphisms between F₂-resistant and F₂-susceptible DNA bulks for identifying the chromosomal location of PmBYYT. A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chromosome 7B, indicating that PmBYYT may be located on this chromosome. A genetic linkage map of PmBYYT consisting of two simple sequence repeat markers and eight SNP markers was developed. The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively. The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay. The flanking markers of gene PmBYYT will benefit marker-assisted selection (MAS) and map-based cloning in breeding wheat cultivars with powdery mildew resistance.

Chinese wheat landrace Youbailan has excellent resistance to powdery mildew caused by Blumeria graminis f. sp. tritici. In the present study, genetic analysis indicated that a recessive gene, tentatively designated pmYBL, was responsible for the powdery mildew resistance of Youbailan. pmYBL was located in the 695-to-715-Mb genomic region of chromosome 7BL, with 19 gene-linked single-nucleotide polymorphism (SNP) markers. It was flanked by SNP1-12 and SNP1-2 with genetic distances of 0.6 and 1.8 centimorgans, respectively. The disease reaction patterns of Youbailan and four cultivars (lines) carrying the powdery mildew (Pm) genes located on chromosome arm 7BL indicated that pmYBL may be allelic or closely linked to these genes. All of the SNP markers linked to pmYBL were diagnostic, indicating that these markers will be useful for pyramiding pmYBL using marker-assisted selection.

Adzuki bean (Vigna angularis) is an important pulse crop, and rust disease severely restricts its production. Identifying resistance genes is essential for accelerating the development of rust-resistant cultivars through marker-assisted breeding. In this study, genotyping-by-sequencing (GBS) was performed on 178 adzuki bean accessions, generating 124.87 Gb of sequencing data and yielding 12,153 high-quality single-nucleotide polymorphism (SNP) markers with an average density of 26.56 SNPs/Mb across the genome. Principal component analysis (PCA) and K-means clustering divided the 178 accessions into three distinct genetic clusters, with the first five principal components explaining 31.90% of the total genetic variation. Population structure analysis based on these SNPs revealed that the cross-entropy criterion reached its minimum at K = 7, partitioning the panel into seven genetic subpopulations (C1–C7). A neighbor-joining phylogenetic tree further resolved the accessions into five major groups. Rust resistance was assessed at the seedling stage under greenhouse conditions with artificial inoculation of Uromyces vignae isolate ZXL01, and at the adult stage under natural field infection at a single experimental site. Genome-wide association analysis (GWAS) was conducted separately for the two assessments and identified fifteen SNPs significantly associated with rust resistance. Ten SNPs were identified at the seedling stage on chromosomes 1 and 3, while the remaining five SNPs were detected at the adult stage on chromosome 9. The SNPs associated with adult-stage rust resistance were converted into Kompetitive Allele-Specific PCR (KASP) markers, which were subsequently validated in an independent panel. The validation confirmed that the resistance-associated alleles were predominantly detected in highly resistant accessions, suggesting that these markers have potential utility for the preliminary screening of rust-resistant germplasm, although further breeding validation is required.