Publications by authors named "Robert A McIntosh"

We analysed the chromosomal structures of two wheat-Thinopyrum intermedium addition lines Z4 and Z5 and resolved the linkage relationship between the leaf rust and stripe rust resistance genes in Z4. Wheat addition lines Z4 and Z5 carrying rust resistance genes from Thinopyrum intermedium (JJJJStSt, 2n = 6x = 42) together with three wheat lines involved in the production of these addition lines were analysed by rust response, 90K SNP genotyping, and molecular cytogenetic analysis. Seedling leaf rust (LR) responses to five diverse pathotypes indicated that the LR resistance gene(s) was located in translocation chromosome T3DS-3AS.

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Article Synopsis
  • Australian wheat cultivars Janz and Sunco possess resistance genes Lr24 and Sr24 from Thinopyrum ponticum, but their specific alien segment sizes were previously unknown.
  • The study utilized advanced techniques like ND-FISH, GISH, and PLUG markers to visualize these alien segments and found that Janz and Sunco have smaller segments compared to US cultivars Agent and Amigo.
  • Additionally, the research identified NBS-LRR receptor genes related to Lr24 and Sr24, and created new molecular markers to aid in the detailed mapping and potential cloning of these important resistance genes.
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The re-emergence of stem rust on wheat in Europe and Africa is reinforcing the ongoing need for durable resistance gene deployment. Here, we isolate from wheat, Sr26 and Sr61, with both genes independently introduced as alien chromosome introgressions from tall wheat grass (Thinopyrum ponticum). Mutational genomics and targeted exome capture identify Sr26 and Sr61 as separate single genes that encode unrelated (34.

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Stem rust is an important disease of wheat that can be controlled using resistance genes. The gene SuSr-D1 identified in cultivar 'Canthatch' suppresses stem rust resistance. SuSr-D1 mutants are resistant to several races of stem rust that are virulent on wild-type plants.

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Background: The successful implantation of cardiac resynchronization therapy (CRT) may be prevented by anatomical variations that preclude the delivery of clinically effective left ventricular (LV) pacing from within the coronary sinus (CS) or its tributaries. Failure of lead delivery, suboptimal LV capture thresholds, or intractable phrenic nerve capture with accompanying diaphragmatic twitch is often encountered. Commonly employed alternative approaches to LV lead delivery, including epicardial, trans-septal, or transapical pacing are associated with significant morbidity.

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Hexaploid wheat has relatively narrow genetic diversity due to its evolution and domestication history compared to its wild relatives that often carry agronomically important traits including resistance to biotic and abiotic stresses. Many genes have been introgressed into wheat from wild relatives using various strategies and protocols. One of the important issues with these introgressions is linkage drag, i.

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Genetic and mutational analyses of wheat leaf rust resistance gene Lr13 and hybrid necrosis gene Ne2 m indicated that they are the same gene. Hybrid necrosis in wheat characterized by chlorosis and eventual necrosis of plant tissues in certain wheat hybrids is controlled by the interaction of complementary dominant genes Ne1 and Ne2 located on chromosome arms 5BL and 2BS, respectively. Multiple alleles at each locus can be identified by differences in necrotic phenotypes when varieties are crossed with a fixed accession of the other genotype.

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Article Synopsis
  • - The study identifies two complementary dominant genes, termed Yr73 and Yr74, responsible for seedling resistance to wheat stripe rust in a resistant selection of the Avocet wheat variety, mapped to chromosome arms 3DL and 5BL.
  • - A chromosomal deletion on 5BL in susceptible Avocet selections was found to explain their lack of resistance, confirmed through genetic mapping and greenhouse tests against avirulent Pst pathotypes.
  • - The research utilized DArT-Seq genotypic analysis on 92 doubled haploid lines to confirm the location of the resistant genes, and fluorescence in situ hybridization (FISH) helped clarify chromosomal variations, supporting the complementary gene model.
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The powdery mildew resistance gene Pm8 derived from rye is located on a 1BL.1RS chromosome translocation in wheat. However, some wheat lines with this translocation do not show resistance to isolates of the wheat powdery mildew pathogen avirulent to Pm8 due to an unknown genetically dominant suppression mechanism.

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Background: Resting echocardiographic measures of cardiac function such as left ventricular ejection fraction correlate poorly with exercise capacity. Assessment during exercise using measures less dependent on hemodynamic loading conditions, such as tissue Doppler imaging (TDI), may more accurately characterize the relationship between cardiac function and exercise capacity.

Methods And Results: One hundred one subjects with various cardiac diagnoses underwent exercise stress echocardiography with simultaneous cardiopulmonary gas exchange analysis.

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Segregating F(3) families, derived from a cross between oat cultivar Swan and the putative single gene line PC68, were used to determine the association of seed storage protein loci and resistance gene analogues (RGAs) with the crown rust resistance gene Pc68. SDS-PAGE analysis detected three avenin loci, AveX, AveY, and AveZ, closely linked to Pc68. Their diagnostic alleles are linked in coupling to Pc68 and were also detected in three additional lines carrying Pc68.

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Genetic suppression of disease resistance is occasionally observed in hexaploid wheat or in its interspecific crosses. The phenotypic effects of genes moved to wheat from relatives with lower ploidy are often smaller than in the original sources, suggesting the presence of modifiers or partial inhibitors in wheat, especially dilution effects caused by possible variation at orthologous loci. However, there is little current understanding of the underlying genetics of suppression.

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Stripe rust is one of the most destructive diseases of wheat. Breeding for resistance is the most economical and environmentally acceptable means to control stripe rust. Genetic studies on resistance sources are very important.

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