Identification of stripe rust resistance loci in Gansu wheat landraces using genome-wide association analysis

Unlocking the potential of spring wheat genetic resources: uncovering resistance sources against leaf rust and yellow rust

Integrating high-throughput phenotyping with multiple complementary GWAS models reduces method-dependent bias and enables reliable identification of novel loci and elite germplasm for durable yellow and leaf rust resistance in wheat. The causal agents of yellow and leaf rust in wheat, Puccinia striiformis f. sp. tritici and Puccinia triticina, pose a serious threat to grain yield and quality worldwide. Growing durable resistant wheat cultivars is an effective protection measure contributing to sustainable agriculture. Many of the known resistance genes, however, have been overcome due to the high genetic diversity and adaptability of pathogen populations. Therefore, the present study aimed to identify novel loci associated with yellow rust and leaf rust in a genome-wide association study using 1984 spring wheat accessions from the German Federal ex situ Genebank. Phenotypic data obtained from a detached-leaf assay were combined with 90,283 genotyping-by-sequencing genome-wide markers. Six significant peak marker-trait associations were identified for yellow rust and leaf rust, respectively. These are located on chromosomes 1D, 2B, 3B, 4A, 4B, 4D, 5A, 6B, and 7D. Six candidate genes were identified close to the identified loci. These findings may be valuable for identifying and deploying genetic resources to broaden the genetic basis of resistance and safeguard durability of resistance against yellow and leaf rust.

Epidemiological Evaluation and Molecular Identification of the Leaf Rust Resistance Gene Lr13 in Selected Egyptian Wheat Cultivars Under Climatic Influences

Exploring the Diversity of Blast Resistance Genes in Rice Lines Using PCR-Based Functional STS Markers

Rice blast, caused by Pyricularia oryzae (syn. Magnaporthe oryzae), remains one of the most destructive diseases of rice worldwide. Developing resistant varieties is a sustainable strategy for disease management, and information on the diversity of blast resistance genes is important for selecting breeding parents. This study evaluated the effectiveness of functional sequence-tagged site (STS) markers for resolving genetic diversity among advanced rice lines derived from multiple-cross populations. A total of 104 genotypes, comprising 100 advanced lines and four parental varieties (Ciherang, Inpari 13, Inpari 10, and Situ Bagendit), were analyzed using eight gene-specific STS markers associated with four blast resistance genes (Pii, Pia, Pikp, and Pita). Polymorphism information content (PIC) values ranged from 0.80 to 0.96, with a mean of 0.89. UPGMA cluster analysis separated the genotypes into two major groups at a similarity coefficient of 0.90, although most lines occurred in one group and lines with the same parental background were distributed among different subgroups. Observed heterozygosity was low (Ho = 0.09), indicating limited resolution for distinguishing closely related lines despite the high PIC values. Functional STS markers were informative for detecting allelic variation but were insufficient for resolving fine-scale relationships within this genetically narrow breeding population. Combining marker analysis with phenotypic evaluation and higher-resolution markers is therefore recommended to improve selection for blast resistance.

QTL Mapping for Leaf Rust Resistance in a Wheat Recombinant Inbred Line Population of Liang66-S/Hengmai28

Leaf rust (LR), caused by Puccinia triticina, is a major constraint to global wheat production. Identifying quantitative trait loci (QTLs), conferring adult-plant resistance (APR), and developing breeder-friendly markers are essential for durable disease control. In this study, a recombinant inbred line (RIL) population derived from Liang66-S × Hengmai28 was evaluated for leaf rust severity across four environments. Maximum disease severity (MDS) showed continuous variation and moderate to high correlations among environments, indicating polygenic inheritance. Five APR QTLs were mapped on chromosomes 2BL, 3BS, 3BL, 7BL and 7DL, explaining 4.5–9.8% of the phenotypic variance (PVE) with LOD scores of 2.9–7.9. Among these, QLr.DFI-2BL, QLr.DFI-3BS, and QLr.DFI-7BL correspond to previously reported APR loci, whereas QLr.DFI-3BL and QLr.DFI-7DL represent potentially novel loci. QLr.DFI-3BL was detected across all four environments, while QLr.DFI-3BS and QLr.DFI-7BL showed the highest R2 (7.7–8.5% and 8.4–9.8%). Multiple defense-related genes within the QTL intervals for LR were identified, including the putative NBS-LRR, the putative BTB/POZ-MATH, F-box, receptor-like kinase, polyphenol oxidase, calcium-dependent protein kinase, peroxidase, and ethylene-responsive transcription factors. Based on the flanking markers, five KASP markers were developed. K-LR-3BS (for QLr.DFI-3BS) and K-LR-7BL (for QLr.DFI-7BL) successfully genotyped a natural population with 120 accessions, with call rates of 100% and 94.2%, and showed significant association with reduced leaf rust severity. However, further validation in diverse genetic backgrounds and populations is required before they can be considered for routine marker-assisted selection. These results provide two KASP markers as promising markers that require further validation in diverse backgrounds and highlight QLr.DFI-3BS and QLr.DFI-7BL as promising targets for fine mapping and eventual cloning of APR genes in wheat.

Identifying marker-trait associations for wheat stem sawfly resistance

Two novel WSS resistance loci were identified on chromosomes 2B and 5A. Characterization of WSS resistance loci will improve breeders’ ability to select to reduce yield loss due to WSS. Wheat stem sawfly (WSS) is a native grass feeding pest of winter wheat (Triticum aestivum L) which is difficult to control since most of its life cycle occurs within the stem of wheat plants. The only well-characterized genetic resistance to WSS is the solid stem locus (Sst1) on chromosome 3B, which exhibits environmental variability. It is critical to identify novel forms of genetic resistance outside of Sst1 to improve the overall resistance of wheat to WSS. In this study, genome-wide association studies (GWAS) were performed on lines in the Colorado State University wheat breeding program grown between 2014 and 2025 field seasons for three traits of interest: heading date (HD), WSS damage in the form of stem cutting (CUT), and stem solidity (SOLID). Significant marker trait associations (MTA) were identified on chromosomes 2B, 2D, 3A, 3B, 5A, and 5D for CUT and 2A, 3B, 4B, and 6A for SOLID. Significant MTA from these GWAS were used to identify beneficial allelic combinations (AC) for WSS resistance. The stem cutting ACs which had the lowest damage estimates were those in which lines possessed the resistant haplotype at every locus assessed (CUT = 2.35, error = 0.21, N = 56). Lines that had all resistant alleles in the stem solidity ACs showed the same superior estimate (SOLID = 14.7, error = 0.78, N = 22). The positive effects of the identified small-effect MTA on CUT and SOLID indicated the importance of including these loci when breeding for WSS resistance.

Association Mapping of Seedling Resistance to Fusarium graminearum Root Rot and Development of KASP Assays in Soybean

Findings identify useful genetic targets and molecular markers for improving soybean resistance to root rot caused by F. graminearum.