Browsing by Author "Raman Dhariwal"

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Genome-wide association study for agronomic and yield-related traits in spring wheat (Triticum aestivum L.) germplasm
(BioMed Central Ltd, 2025) Ankita Thakur; Raman Dhariwal; Hannes Kumar Karwat; Vinod Kumar Mishra; Sandeep K. Sharma; Mukesh Kumar Singh; Sundeep Naresh Kumar; Neeraj Kumar Vasistha
Background: Common wheat (Triticum aestivum L.) is one of the most widely grown and consumed cereal crops, but its complicated genome makes it difficult to study how genes affect important agronomic and yield-related traits. Genome-wide association study (GWAS) is a useful method for finding specific loci that control complex agronomic and yield-related traits. Results: The present investigation revealed significant phenotypic variability across the genotypes examined for all traits. The broad sense heritability (H2) for all traits ranged from 0.50 to 0.71 (Env1; 2021–2022) and 0.53 to 0.81 (Env2; 2022–2023). Using two environments’ phenotypic data, and high-throughput single-nucleotide polymorphisms (SNPs) genotypic data of 20,996 markers, we discovered 114 grain-yield-related quantitative trait loci (QTLs) and 300 associated SNP markers. Eighty-five of the identified markers were stable, consistently detected across environments (Env1 and Env2) and combined environment (CE) data, and showed a significant association with 32 different QTLs. The trait with the most associated QTLs (28) was the number of fertile tillers (NFT), with 70 markers. This was followed by 20 QTLs for each, spike length (SL) and spikelet number per spike (SPS), with 69 and 82 SNPs, respectively. Conversely, six SNPs that exhibited association with multiple traits were also identified. Twenty-nine of the total 114 identified QTLs were located in chromosomal positions where at least one marker-trait association had been previously identified. Conclusion: This study has found new SNPs, and useful QTLs that may help us to understand the biological processes behind each studied trait. Further validation in various genetic backgrounds and environments is necessary to confirm the potential utility of the significant alleles found in this study for breeding wheat varieties with improved agronomic and yield-related traits. © The Author(s) 2025.
Genome-Wide Association Study Reveals Novel Powdery Mildew Resistance Loci in Bread Wheat
(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Ramandeep Kaur; Neeraj Kumar Vasistha; Vikas Kumar Ravat; Vinod Kumar Mishra; Sandeep Sharma; Arun Kumar Joshi; Raman Dhariwal
Powdery mildew (PM), caused by the fungal pathogen Blumeria graminis f. sp. tritici (Bgt), significantly threatens global bread wheat production. Although the use of resistant cultivars is an effective strategy for managing PM, currently available wheat cultivars lack sufficient levels of resistance. To tackle this challenge, we conducted a comprehensive genome-wide association study (GWAS) using a diverse panel of 286 bread wheat genotypes. Over three consecutive years (2020–2021, 2021–2022, and 2022–2023), these genotypes were extensively evaluated for PM severity under field conditions following inoculation with virulent Bgt isolates. The panel was previously genotyped using the Illumina 90K Infinium iSelect assay to obtain genome-wide single-nucleotide polymorphism (SNP) marker coverage. By applying FarmCPU, a multilocus mixed model, we identified a total of 113 marker–trait associations (MTAs) located on chromosomes 1A, 1B, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6B, 7A, and 7B at a significance level of p ≤ 0.001. Notably, four novel MTAs on chromosome 6B were consistently detected in 2020–2021 and 2021–2022. Furthermore, within the confidence intervals of the identified SNPs, we identified 96 candidate genes belonging to different proteins including 12 disease resistance/host–pathogen interaction-related protein families. Among these, protein kinases, leucine-rich repeats, and zinc finger proteins were of particular interest due to their potential roles in PM resistance. These identified loci can serve as targets for breeding programs aimed at developing disease-resistant wheat cultivars. © 2023 His Majesty the King in Right of Canada.