Publications by authors named "Ron Knox"

Durum wheat () is threatened by the appearance of new virulent races of leaf rust, caused by , in recent years. This study was conducted to determine the leaf rust resistance in a modern Canadian durum cultivar, Strongfield. Six populations derived from crosses of Strongfield with six tetraploid wheat lines, respectively, were tested at the seedling plant stage with different races.

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Background: Optimum moisture in straw and grain at maturity is important for timely harvesting of wheat. Grain harvested at the right time has reduced chance of being affected by adverse weather conditions which is important to maintain grain quality and end use functionality. Wheat varieties with a short dry down period could help in timely harvest of the crop.

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Article Synopsis
  • - Fusarium head blight (FHB) negatively impacts durum wheat quality by causing Fusarium damaged kernels (FDK) and deoxynivalenol (DON) contamination, with the DT696 line showing less susceptibility compared to other cultivars.
  • - The study utilized a SNP high-density genetic map from a DT707/DT696 population to identify QTL (quantitative trait loci) responsible for resistance against DON and FDK, discovering four DON resistance QTL and two FDK resistance QTL across varying years.
  • - Breeder-friendly KASP markers were developed for diagnosing resistance QTL on specific chromosomes, aiding in future durum wheat breeding to enhance disease resistance by utilizing favorable alleles from the DT696 line.
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Studies on the northeastern American native hops ( ssp ) from the Canadian Maritimes are scarce. This study aimed to evaluate the genetic structure and diversity among 25 wild-collected hops from three Canadian Maritime provinces using microsatellite (simple sequence repeat (SSR)) markers. Based on 43 SSR markers, four distinct subgroups were found, with a low molecular variance (19%) between subgroups and a high variance (81%) within subgroups.

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Fusarium head blight (FHB) is a highly destructive fungal disease of wheat to which host resistance is quantitatively inherited and largely influenced by the environment. Resistance to FHB has been associated with taller height and later maturity; however, a further understanding of these relationships is needed. An association mapping panel (AMP) of 192 predominantly Canadian spring wheat was genotyped with the wheat 90K single-nucleotide polymorphism (SNP) array.

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Article Synopsis
  • Fusarium head blight (FHB) is a significant problem for wheat production in western Canada, necessitating ongoing research to develop resistant germplasm and improve genetic selection techniques.
  • This study aimed to identify quantitative trait loci (QTL) related to FHB resistance in two wheat cultivars, assessing a large population across various locations for different agronomic traits.
  • The research found multiple QTL linked to FHB resistance, with significant markers located on chromosomes 2A, 3B, 4B, 5A, 6A, and 6D, and highlighted the co-localization of some resistance QTL with traits like plant height and days to maturity.
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The Canada Western Red Spring wheat ( L.) cultivars AAC Concord, AAC Prevail, CDC Hughes, Lillian, Glenlea, and elite line BW961 express a spectrum of resistance to leaf rust caused by Eriks. This study aimed to identify and map the leaf rust resistance of the cultivars using three doubled haploid populations, AAC Prevail/BW961 (PB), CDC Hughes/AAC Concord (HC), and Lillian/Glenlea (LG).

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A major QTL on chromosome arm 4BS was associated with reduced spike shattering and reduced plant height in coupling phase, and a second major QTL associated with reduced spike shattering was detected on chromosome arm 5AL in the same wheat variety Carberry. Spike shattering can cause severe grain yield loss in wheat. Development of cultivars with reduced shattering but having easy mechanical threshability is the target of wheat breeding programs.

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The hexaploid spring wheat cultivar, Carberry, was registered in Canada in 2009, and has since been grown over an extensive area on the Canadian Prairies. Carberry has maintained a very high level of leaf rust ( Eriks.) resistance since its release.

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Grain protein concentration (GPC) is an important trait in durum cultivar development as a major determinant of the nutritional value of grain and end-use product quality. However, it is challenging to simultaneously select both GPC and grain yield (GY) due to the negative correlation between them. To characterize quantitative trait loci (QTL) for GPC and understand the genetic relationship between GPC and GY in Canadian durum wheat, we performed both traditional and conditional QTL mapping using a doubled haploid (DH) population of 162 lines derived from Pelissier × Strongfield.

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Durum wheat is an economically important crop for Canadian farmers. Fusarium head blight (FHB) is one of the most destructive diseases that threatens durum production in Canada. FHB reduces yield and end-use quality and most commonly contaminates the grain with the fungal mycotoxin deoxynivalenol, also known as DON.

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Article Synopsis
  • Representative genetic collections help understand diversity and support breeding goals by identifying beneficial traits in crops.
  • The Global Durum Wheat Panel (GDP) includes 1,011 wheat accessions, capturing 94-97% of the genetic diversity from 2,500 tetraploid wheat samples, featuring a mix of modern and ancient strains.
  • Analysis shows high genetic diversity in modern wheat from specific breeding programs, with distinct genetic clusters identified, and key loci associated with important traits like plant height and quality, which can aid future breeding efforts.
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Genomic predictions across environments and within populations resulted in moderate to high accuracies but across-population genomic prediction should not be considered in wheat for small population size. Genomic selection (GS) is a marker-based selection suggested to improve the genetic gain of quantitative traits in plant breeding programs. We evaluated the effects of training population (TP) composition, cross-validation design, and genetic relationship between the training and breeding populations on the accuracy of GS in spring wheat (Triticum aestivum L.

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Plant breeding leads to the genetic improvement of target traits by selecting a small number of genotypes from among typically large numbers of candidate genotypes after careful evaluation. In this study, we first investigated how mutations at conserved nucleotide sites normally viewed as deleterious, such as nonsynonymous sites, accumulated in a wheat, , breeding lineage. By comparing a 150 year old ancestral and modern cultivar, we found recent nucleotide polymorphisms altered amino acids and occurred within conserved genes at frequencies expected in the absence of purifying selection.

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Article Synopsis
  • The study focused on the recruitment of specific arbuscular mycorrhizal (AM) fungal communities by various old and new cultivars of durum wheat cultivated in Eastern Canada under phosphorus-limiting conditions.
  • Researchers identified a total of 317 amplicon sequence variants (ASVs) belonging to the Glomeromycota phylum through MiSeq amplicon sequencing, revealing a core AM fungal community across soil, rhizosphere, and roots.
  • There was little variation in root colonization percentages among different durum wheat cultivars, indicating that these cultivars generally share similar AM fungal communities, although some differences in fungal abundance were noted among specific cultivars.
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Background: Discovering single nucleotide polymorphisms (SNPs) from agriculture crop genome sequences has been a widely used strategy for developing genetic markers for several applications including marker-assisted breeding, population diversity studies for eco-geographical adaption, genotyping crop germplasm collections, and others. Accurately detecting SNPs from large polyploid crop genomes such as wheat is crucial and challenging. A few variant calling methods have been previously developed but they show a low concordance between their variant calls.

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Article Synopsis
  • Private and public breeding programs, along with universities and companies, have generated large amounts of genomic sequence data, raising challenges in data management and analysis.
  • Detailed phenotype data and increasing genomic data present opportunities to enhance our understanding of quantitative genetics and facilitate research through data harmonization.
  • The paper proposes a covariance-based method for combining unbalanced omics data, demonstrating its potential in genomic prediction and improving insights into trait relationships from multiple phenotypic experiments.
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Background: The genetics of resistance to loose smut of wheat (Triticum aestivum L.) caused by the fungus Ustilago tritici (Pers.) Rostr.

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The durum wheat line DT696 is a source of moderate Fusarium head blight (FHB) resistance. Previous analysis using a bi-parental population identified two FHB resistance quantitative trait loci (QTL) on chromosome 5A: 5A1 was co-located with a plant height QTL, and 5A2 with a major maturity QTL. A Genome-Wide Association Study (GWAS) of DT696 derivative lines from 72 crosses based on multi-environment FHB resistance, plant height, and maturity phenotypic data was conducted to improve the mapping resolution and further elucidate the genetic relationship of height and maturity with FHB resistance.

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Growing resistant wheat (Triticum aestivum L) varieties is an important strategy for the control of leaf rust, caused by Puccinia triticina Eriks. This study sought to identify the chromosomal location and effects of leaf rust resistance loci in five Canadian spring wheat cultivars. The parents and doubled haploid lines of crosses Carberry/AC Cadillac, Carberry/Vesper, Vesper/Lillian, Vesper/Stettler and Stettler/Red Fife were assessed for leaf rust severity and infection response in field nurseries in Canada near Swift Current, SK from 2013 to 2015, Morden, MB from 2015 to 2017 and Brandon, MB in 2016, and in New Zealand near Lincoln in 2014.

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Gluten strength is one of the factors that determine the end-use quality of durum wheat and is an important breeding target for this crop. To characterize the quantitative trait loci (QTL) controlling gluten strength in Canadian durum wheat cultivars, a population of 162 doubled haploid (DH) lines segregating for gluten strength and derived from cv. Pelissier × cv.

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Four QTL for ergot resistance (causal pathogen Claviceps purpurea) have been identified in the durum wheat cultivar Greenshank. Claviceps purpurea is a pathogen of grasses that infects flowers, replacing the seed with an ergot sclerotium. Ergot presents a significant problem to rye, barley and wheat, in particular hybrid seed production systems.

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Background: Fusarium head blight (FHB) resistance in the durum wheat breeding gene pool is rarely reported. Triticum turgidum ssp. carthlicum line Blackbird is a tetraploid relative of durum wheat that offers partial FHB resistance.

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Based on their consistency over environments, two QTL identified in Lillian on chromosomes 5A and 7A could be useful targets for marker assisted breeding of common bunt resistance. Common bunt of wheat (Triticum aestivum L.) caused by Tilletia tritici and T.

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