Stem Rust

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Yue Jin - One of the best experts on this subject based on the ideXlab platform.

  • Stem Rust resistance in wheat is suppressed by a subunit of the mediator complex
    Nature communications, 2020
    Co-Authors: Colin W. Hiebert, Matthew N Rouse, Matthew J. Moscou, Tim Hewitt, Burkhard Steuernagel, Inma Hernández-pinzón, Phon Green, Vincent Pujol, Peng Zhang, Yue Jin
    Abstract:

    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. Here we identify SuSr-D1 by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of Stem Rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation in med15b.D mutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to Stem Rust. Suppression is a common phenomenon and this study provides novel insight into suppression of Rust resistance in wheat.

  • Molecular marker dissection of Stem Rust resistance in Nebraska bread wheat germplasm.
    Scientific reports, 2019
    Co-Authors: Amira M. I. Mourad, Ahmed Sallam, Vikas Belamkar, Stephen N. Wegulo, Guihua Bai, Ezzat Mahdy, B. R. Bakheit, Atif Abo El-wafa, Yue Jin, P. Stephen Baenziger
    Abstract:

    Stem Rust (caused by Puccinia graminis f. sp. tritici) is a major disease of wheat. To understand the genetic basis of Stem Rust resistance in Nebraska winter wheat, a set of 330 genotypes representing two nurseries (DUP2015 and TRP2015) were evaluated for resistance to a Nebraska Stem Rust race (QFCSC) in two replications. The TRP2015 nursery was also evaluated for its resistance to an additional 13 Stem Rust races. The analysis of variance revealed significant variation among genotypes in both populations for Stem Rust resistance. Nine Stem Rust genes, Sr6, Sr31, Sr1RSAmigo, Sr24, Sr36, SrTmp, Sr7b, Sr9b, and Sr38, were expected and genotyped using gene-specific markers. The results of genetic analysis confirmed the presence of seven Stem Rust resistance genes. One genotype (NE15680) contained target alleles for five Stem Rust resistance genes and had a high level of Stem Rust resistance against different races. Single marker analysis indicated that Sr24 and Sr38 were highly significantly associated with Stem Rust resistance in the DUP2015 and TRP2015 nurseries, respectively. Linkage disequilibrium analysis identified the presence of 17 SNPs in high linkage with the Sr38-specific marker. These SNPs potentially tagging the Sr38 gene could be used in marker-assisted selection after validating them in additional genetic backgrounds.

  • characterization of thinopyrum species for wheat Stem Rust resistance and ploidy level
    Crop Science, 2014
    Co-Authors: Qi Zheng, Daryl L Klindworth, Timothy L Friesen, Ai Feng Liu, Shaobin Zhong, Yue Jin
    Abstract:

    In the tribe Triticeae, several Thinopyrum species have been used as sources of resistance to Stem Rust (caused by Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn., abbreviated as Pgt) and other wheat (Triticum aestivum L.) diseases. To identify novel sources of resistance to Pgt race TTKSK (Ug99), we evaluated and characterized the Stem Rust resistance of 242 accessions belonging to five Thinopyrum species, including beach wheatgrass [Th. bessarabicum (Savul. & Rayss) A. Love], diploid tall wheatgrass [Th. elongatum (Host) D.R. Dewey], intermediate wheatgrass [Th. intermedium (Host) Barkworth & D. R. Dewey], sand cough or sea wheatgrass [Th. junceum (L.) A. Love], and decaploid tall wheatgrass [Th. ponticum (Podp.) Barkworth & D.R. Dewey]. These accessions were evaluated for seedling reactions to nine Pgt races (TTKSK, TTTTF, TRTTF, RTQQC, QFCSC, TCMJC, TPMKC, TMLKC, and TPPKC), genotyped with molecular markers linked to four Stem Rust resistance genes (Sr24, Sr25, Sr26, and Sr43) derived from Thinopyrum species, and examined for ploidy levels. All accessions but one (Th. elongatum PI 531718) were resistant to all or most races. Most of the Th. elongatum and Th. ponticum accessions showed near-immunity to all of the races while the accessions of the other three species (Th. bessarabicum, Th. intermedium, and Th. junceum) had varied levels of resistance ranging from near immunity to moderate resistance. Molecular marker analysis showed that most of the markers appeared to be species- or genus-specific rather than linked to a gene of interest, and thus genotyping analysis was of limited value. Comparisons of infection types of accessions based on ploidy level suggested that higher ploidy level was associated with higher levels of Stem Rust resistance. The results from this study substantiate that the Thinopyrum species are a rich source of Stem Rust resistance.

  • Characterization of Sr9h, a wheat Stem Rust resistance allele effective to Ug99
    TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik, 2014
    Co-Authors: Matthew N Rouse, Zacharias A. Pretorius, Jayaveeramuthu Nirmala, Yue Jin, T Fetch, Shiaoman Chao, Colin W. Hiebert
    Abstract:

    Key message Wheat Stem Rust resistance gene SrWeb is an allele at the Sr9 locus that confers resistance to Ug99. Abstract race TTKSK (Ug99) of Puccinia graminis f. sp. tritici, the causal fungus of Stem Rust, threatens global wheat production because of its broad virulence to current wheat cultivars. A recently identified Ug99 resistance gene from cultivar Webster, temporarily designated as SrWeb, mapped near the Stem Rust resistance gene locus Sr9. We determined that SrWeb is also present in Ug99 resistant cultivar Gabo 56 by comparative mapping and an allelism test. Analysis of resistance in a population segregating for both Sr9e and SrWeb demonstrated that SrWeb is an allele at the Sr9 locus, which subsequently was designated as Sr9h. Webster and

  • Haplotype diversity of Stem Rust resistance loci in uncharacterized wheat lines
    Molecular Breeding, 2010
    Co-Authors: Sixin Liu, Ravi P. Singh, Yue Jin, James A. Anderson, Jorge Dubcovsky, Gina Brown-guidera, Sridhar Bhavani, Alexey Morgounov
    Abstract:

    Stem Rust is one of the most destructive diseases of wheat worldwide. The recent emergence of wheat Stem Rust race Ug99 (TTKS based on the North American Stem Rust race nomenclature syStem) and related strains threaten global wheat production because they overcome widely used genes that had been effective for many years. Host resistance is likely to be more durable when several Stem Rust resistance genes are pyramided in a single wheat variety; however, little is known about the resistance genotypes of widely used wheat germplasm. In this study, a diverse collection of wheat germplasm was haplotyped for Stem Rust resistance genes Sr2, Sr22, Sr24, Sr25, Sr26, Sr36, Sr40, and 1A.1R using linked microsatellite or simple sequence repeat (SSR) and sequence tagged site (STS) markers. Haplotype analysis indicated that 83 out of 115 current wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT) likely carry Sr2. Among those, five out of 94 CIMMYT spring lines tested had both Sr2 and Sr25 haplotypes. Five out of 22 Agriculture Research Service (ARS) lines likely have Sr2 and a few have Sr24, Sr36, and 1A.1R. Two out of 43 Chinese accessions have Sr2. No line was found to have the Sr26 and Sr40 haplotypes in this panel of accessions. DArT genotyping was used to identify new markers associated with the major Stem resistance genes. Four DArT markers were significantly associated with Sr2 and one with Sr25. Principal component analysis grouped wheat lines from similar origins. Almost all CIMMYT spring wheats were clustered together as a large group and separated from the winter wheats. The results provide useful information for Stem Rust resistance breeding and pyramiding.

Matthew N Rouse - One of the best experts on this subject based on the ideXlab platform.

  • Stem Rust resistance in wheat is suppressed by a subunit of the mediator complex
    Nature communications, 2020
    Co-Authors: Colin W. Hiebert, Matthew N Rouse, Matthew J. Moscou, Tim Hewitt, Burkhard Steuernagel, Inma Hernández-pinzón, Phon Green, Vincent Pujol, Peng Zhang, Yue Jin
    Abstract:

    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. Here we identify SuSr-D1 by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of Stem Rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation in med15b.D mutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to Stem Rust. Suppression is a common phenomenon and this study provides novel insight into suppression of Rust resistance in wheat.

  • Genomic Dissection of Nonhost Resistance to Wheat Stem Rust in Brachypodium distachyon.
    Molecular plant-microbe interactions : MPMI, 2019
    Co-Authors: Rafael Della Coletta, Matthew N Rouse, Candice N. Hirsch, Aaron J. Lorenz, David F. Garvin
    Abstract:

    The emergence of new races of Puccinia graminis f. sp. tritici, the causal pathogen of wheat Stem Rust, has spurred interest in developing durable resistance to this disease in wheat. Nonhost resistance holds promise to help control this and other diseases because it is durable against nonadapted pathogens. However, the genetic and molecular basis of nonhost resistance to wheat Stem Rust is poorly understood. In this study, the model grass Brachypodium distachyon, a nonhost of P. graminis f. sp. tritici, was used to genetically dissect nonhost resistance to wheat Stem Rust. A recombinant inbred line (RIL) population segregating for response to wheat Stem Rust was evaluated for resistance. Evaluation of genome-wide cumulative single nucleotide polymorphism allele frequency differences between contrasting pools of resistant and susceptible RILs followed by molecular marker analysis identified six quantitative trait loci (QTL) that cumulatively explained 72.5% of the variation in Stem Rust resistance. Two of the QTLs explained 31.7% of the variation, and their interaction explained another 4.6%. Thus, nonhost resistance to wheat Stem Rust in B. distachyon is genetically complex, with both major and minor QTLs acting additively and, in some cases, interacting. These findings will guide future research to identify genes essential to nonhost resistance to wheat Stem Rust.

  • Genetic Characterization of Stem Rust Resistance in a Global Spring Wheat Germplasm Collection
    Crop Science, 2017
    Co-Authors: Liangliang Gao, Matthew N Rouse, Paul D. Mihalyov, Peter Bulli, Michael O. Pumphrey, James A. Anderson
    Abstract:

    Stem Rust, caused by the fungus Puccinia graminis Pers. f. sp. tritici Ericks, is one of the most damaging diseases of wheat (Triticum aestivum L.). The recent emergence of the Stem Rust Ug99 race group poses a serious threat to world wheat production. Utilization of genetic resistance in cultivar development is the optimal way to control Stem Rust. Here, we report association mapping of Stem Rust resistance in a global spring wheat germplasm collection (2152 accessions) genotyped with the wheat iSelect 9K single-nucleotide polymorphism array. Using a unified mixed model method (or QK method), we identified a total of 47 loci that were significantly associated with various Stem Rust resistance traits including field disease resistance and seedling resistance against multiple Stem Rust pathogen races including BCCBC, TRTTF, TTKSK (Ug99), and TTTTF. The 47 loci could be further condensed into 11 quantitative trait locus (QTL) regions according to linkage disequilibrium information among adjacent markers. We postulate that these QTLs represent known Stem Rust resistance genes including Sr2, Sr6, Sr7a, Sr8a, Sr9h, Sr13, Sr28, and Sr36. We further employed a multilocus mixed model to explore marker-trait associations and identified two additional QTLs (one potentially represents Sr31) that were significantly associated with Stem Rust resistance against various races. Combinations of the most significant loci for each trait explained up to 38.6% of the phenotypic variance. Markers identified through this study could be used to track the genes or QTLs. Accessions with high numbers of resistance-associated alleles may serve as important breeding materials for Stem Rust resistance.

  • Sources of Stem Rust Resistance in Wheat-Alien Introgression Lines.
    Plant disease, 2016
    Co-Authors: Mahbubjon Rahmatov, Matthew N Rouse, Zacharias A. Pretorius, Brian J. Steffenson, Sridhar Bhavani, Staffan Andersson, R. Wanyera, Andreas Houben, Nazari Kumarse, Eva Johansson
    Abstract:

    Stem Rust is one of the most devastating diseases of wheat. Widely virulent races of the pathogen in the Ug99 lineage (e.g., TTKSK) are threatening wheat production worldwide; therefore, there is an urgent need to enhance the diversity of resistance genes in the crop. The objectives of this study were to identify new sources of resistance in wheat-alien introgression derivatives from Secale cereale, Leymus mollis, L. racemosus, and Thinopyrum junceiforme, postulate genes conferring the resistance, and verify the postulated genes by use of molecular markers. From seedling tests conducted in the greenhouse, the presence of seven known Stem Rust resistance genes (Sr7b, Sr8a, Sr9d, Sr10, Sr31, Sr36, and SrSatu) was postulated in the wheat-alien introgression lines. More lines possessed a high level of resistance in the field compared with the number of lines that were resistant at the seedling stage. Three 2R (2D) wheat-rye substitution lines (SLU210, SLU238, and SLU239) seemed likely to possess new genes for resistance to Stem Rust based on their resistance pattern to 13 different Stem Rust races but the genes responsible could not be identified. Wheat-rye, wheat-L. racemosus, and wheat-L. mollis substitutions or translocations with single and multiple interchanges of chromosomes, in particular of the B and D chromosomes of wheat, were verified by a combination of genomic in situ hybridization and molecular markers. Thus, the present study identified novel resistance genes originating from different alien introgressions into the wheat genome of the evaluated lines. Such genes may prove useful in enhancing the diversity of Stem Rust resistance in wheat against widely virulent pathogen races such as those in the Ug99 lineage.

  • Major gene for field Stem Rust resistance co-locates with resistance gene Sr12 in 'thatcher' wheat
    PLoS ONE, 2016
    Co-Authors: Colin W. Hiebert, Matthew N Rouse, Curt A. Mccartney, Tom Fetch, Harbans Bariana, James A. Kolmer, Jordan Briggs, Frédéric Choulet, Wolfgang Spielmeyer
    Abstract:

    Stem Rust, caused by Puccinia graminis (Pgt), is a damaging disease of wheat that can be controlled by utilizing effective Stem Rust resistance genes. ` Thatcher' wheat carries complex resistance to Stem Rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in ` Thatcher' and look for genetic interactions with Lr34. A RIL population was tested for Stem Rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced Stem Rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in Stem Rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field Stem Rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for ` Thatcher'-derived APR in several environments and this resistance was enhanced in the presence of Lr34.

Brian J. Steffenson - One of the best experts on this subject based on the ideXlab platform.

  • Mapping adult plant Stem Rust resistance in barley accessions Hietpas-5 and GAW-79.
    TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik, 2018
    Co-Authors: Austin J. Case, Zacharias A. Pretorius, Gina Brown-guedira, Godwin Macharia, Sridhar Bhavani, Vicky Coetzee, Frederik Kloppers, Priyanka Tyagi, Brian J. Steffenson
    Abstract:

    Key message Major Stem Rust resistance QTLs proposed to be Rpg2 from Hietpas-5 and Rpg3 from GAW-79 were identified in chromosomes 2H and 5H, respectively, and will enhance the diversity of Stem Rust resistance in barley improvement programs. Stem Rust is a devastating disease of cereal crops worldwide. In barley (Hordeum vulgare ssp. vulgare), the disease is caused by two pathogens: Puccinia graminis f. sp. secalis (Pgs) and Puccinia graminis f. sp. tritici (Pgt). In North America, the Stem Rust resistance gene Rpg1 has protected barley from serious losses for more than 60 years; however, widely virulent Pgt races from Africa in the Ug99 group threaten the crop. The accessions Hietpas-5 (CIho 7124) and GAW-79 (PI 382313) both possess moderate-to-high levels of adult plant resistance to Stem Rust and are the sources of the resistance genes Rpg2 and Rpg3, respectively. To identify quantitative trait loci (QTL) for Stem Rust resistance in Hietpas-5 and GAW-79, two biparental populations were developed with Hiproly (PI 60693), a Stem Rust-susceptible accession. Both populations were phenotyped to the North American Pgt races of MCCFC, QCCJB, and HKHJC in St. Paul, Minnesota, and to African Pgt races (predominately TTKSK in the Ug99 group) in Njoro, Kenya. In the Hietpas-5/Hiproly population, a major effect QTL was identified in chromosome 2H, which is proposed as the location for Rpg2. In the GAW-79/Hiproly population, a major effect QTL was identified in chromosome 5H and is the proposed location for Rpg3. These QTLs will enhance the diversity of Stem Rust resistance in barley improvement programs.

  • genome wide association mapping of Stem Rust resistance in hordeum vulgare subsp spontaneum
    G3: Genes Genomes Genetics, 2017
    Co-Authors: Ahmad H Sallam, Priyanka Tyagi, Gina Brownguedira, Gary J Muehlbauer, Alex Hulse, Brian J. Steffenson
    Abstract:

    Stem Rust was one of the most devastating diseases of barley in North America. Through the deployment of cultivars with the resistance gene Rpg1, losses to Stem Rust have been minimal over the past 70 yr. However, there exist both domestic (QCCJB) and foreign (TTKSK aka isolate Ug99) pathotypes with virulence for this important gene. To identify new sources of Stem Rust resistance for barley, we evaluated the Wild Barley Diversity Collection (WBDC) (314 ecogeographically diverse accessions of Hordeum vulgare subsp. spontaneum) for seedling resistance to four pathotypes (TTKSK, QCCJB, MCCFC, and HKHJC) of the wheat Stem Rust pathogen (Puccinia graminis f. sp. tritici, Pgt) and one isolate (92-MN-90) of the rye Stem Rust pathogen (P. graminis f. sp. secalis, Pgs). Based on a coefficient of infection, the frequency of resistance in the WBDC was low ranging from 0.6% with HKHJC to 19.4% with 92-MN-90. None of the accessions was resistant to all five cultures of P. graminis. A genome-wide association study (GWAS) was conducted to map Stem Rust resistance loci using 50,842 single-nucleotide polymorphic markers generated by genotype-by-sequencing and ordered using the new barley reference genome assembly. After proper accounting for genetic relatedness and structure among accessions, 45 quantitative trait loci were identified for resistance to P. graminis across all seven barley chromosomes. Three novel loci associated with resistance to TTKSK, QCCJB, MCCFC, and 92-MN-90 were identified on chromosomes 5H and 7H, and two novel loci associated with resistance to HKHJC were identified on chromosomes 1H and 3H. These novel alleles will enhance the diversity of resistance available for cultivated barley.

  • Sources of Stem Rust Resistance in Wheat-Alien Introgression Lines.
    Plant disease, 2016
    Co-Authors: Mahbubjon Rahmatov, Matthew N Rouse, Zacharias A. Pretorius, Brian J. Steffenson, Sridhar Bhavani, Staffan Andersson, R. Wanyera, Andreas Houben, Nazari Kumarse, Eva Johansson
    Abstract:

    Stem Rust is one of the most devastating diseases of wheat. Widely virulent races of the pathogen in the Ug99 lineage (e.g., TTKSK) are threatening wheat production worldwide; therefore, there is an urgent need to enhance the diversity of resistance genes in the crop. The objectives of this study were to identify new sources of resistance in wheat-alien introgression derivatives from Secale cereale, Leymus mollis, L. racemosus, and Thinopyrum junceiforme, postulate genes conferring the resistance, and verify the postulated genes by use of molecular markers. From seedling tests conducted in the greenhouse, the presence of seven known Stem Rust resistance genes (Sr7b, Sr8a, Sr9d, Sr10, Sr31, Sr36, and SrSatu) was postulated in the wheat-alien introgression lines. More lines possessed a high level of resistance in the field compared with the number of lines that were resistant at the seedling stage. Three 2R (2D) wheat-rye substitution lines (SLU210, SLU238, and SLU239) seemed likely to possess new genes for resistance to Stem Rust based on their resistance pattern to 13 different Stem Rust races but the genes responsible could not be identified. Wheat-rye, wheat-L. racemosus, and wheat-L. mollis substitutions or translocations with single and multiple interchanges of chromosomes, in particular of the B and D chromosomes of wheat, were verified by a combination of genomic in situ hybridization and molecular markers. Thus, the present study identified novel resistance genes originating from different alien introgressions into the wheat genome of the evaluated lines. Such genes may prove useful in enhancing the diversity of Stem Rust resistance in wheat against widely virulent pathogen races such as those in the Ug99 lineage.

  • Stem Rust spores elicit rapid RPG1 phosphorylation
    Molecular plant-microbe interactions : MPMI, 2010
    Co-Authors: Jayaveeramuthu Nirmala, Tom Drader, Xianming Chen, Brian J. Steffenson, Andris Kleinhofs
    Abstract:

    Stem Rust threatens cereal production worldwide. Understanding the mechanism by which durable resistance genes, such as Rpg1, function is critical. We show that the RPG1 protein is phosphorylated within 5 min by exposure to spores from avirulent but not virulent races of Stem Rust. Transgenic mutants encoding an RPG1 protein with an in vitro inactive kinase domain fail to phosphorylate RPG1 in vivo and are susceptible to Stem Rust, demonstrating that phosphorylation is a prerequisite for disease resistance. Protein kinase inhibitors prevent RPG1 phosphorylation and result in susceptibility to Stem Rust, providing further evidence for the importance of phosphorylation in disease resistance. We conclude that phosphorylation of the RPG1 protein by the kinase activity of the pK2 domain induced by the interaction with an unknown pathogen spore product is required for resistance to the avirulent Stem Rust races. The pseudokinase pK1 domain is required for disease resistance but not phosphorylation. The very rapid phosphorylation of RPG1 suggests that an effector is already present in or on the Stem Rust urediniospores when they are placed on the leaf surface. However, spores must be alive, as determined by their ability to germinate, in order to elicit RPG1 phosphorylation.

  • Genetics of resistance to wheat leaf Rust, Stem Rust, and powdery mildew in Aegilops sharonensis.
    Phytopathology, 2008
    Co-Authors: Pablo D. Olivera, E. Millet, Y. Anikster, Brian J. Steffenson
    Abstract:

    Olivera, P. D., Millet, E., Anikster, Y., and Steffenson, B. J. 2008. Genetics of resistance to wheat leaf Rust, Stem Rust, and powdery mildew in Aegilops sharonensis. Phytopathology 98:353-358. Aegilops sharonensis (Sharon goatgrass) is a wild relative of wheat and a rich source of genetic diversity for disease resistance. The objectives of this study were to determine the genetic basis of leaf Rust, Stem Rust, and powdery mildew resistance in A. sharonensis and also the allelic relationships between genes controlling resistance to each disease. Progeny from crosses between resistant and susceptible accessions were evaluated for their disease reaction at the seedling and/or adult plant stage to determine the number and action of genes conferring resistance. Two different genes conferring resistance to leaf Rust races THBJ and BBBB were identified in accessions 1644 and 603. For Stem Rust, the same single gene was found to confer resistance to race TTTT in accessions 1644 and 2229. Resistance to Stem Rust race TPMK was conferred by two genes in accessions 1644 and 603. A contingency test revealed no association between genes conferring resistance to leaf Rust race THBJ and Stem Rust race TTTT or between genes conferring resistance to Stem Rust race TTTT and powdery mildew isolate UM06-01, indicating that the respective resistance genes are not linked. Three accessions (1644, 2229, and 1193) were found to carry a single gene for resistance to powdery mildew. Allelism tests revealed that the resistance gene in accession 1644 is different from the respective single genes present in either 2229 or 1193. The simple inheritance of leaf Rust, Stem Rust, and powdery mildew resistance in A. sharonensis should simplify the transfer of resistance to wheat in wide crosses.

Burkhard Steuernagel - One of the best experts on this subject based on the ideXlab platform.

  • the wheat sr22 sr33 sr35 and sr45 genes confer resistance against Stem Rust in barley
    Plant Biotechnology Journal, 2020
    Co-Authors: Asyraf Md M Hatta, Oadi Matny, Mark A Smedley, Soma Chakraborty, Dhara Bhatt, Xiaodi Xia, Sanu Arora, Sreya Ghosh, Burkhard Steuernagel
    Abstract:

    In the last 20 years, Stem Rust caused by the fungus Puccinia graminis f. sp. tritici (Pgt), has re-emerged as a major threat to wheat and barley production in Africa and Europe. In contrast to wheat with 82 designated Stem Rust (Sr) resistance genes, barley's genetic variation for Stem Rust resistance is very narrow with only ten resistance genes genetically identified. Of these, only one complex locus consisting of three genes is effective against TTKSK, a widely virulent Pgt race of the Ug99 tribe which emerged in Uganda in 1999 and has since spread to much of East Africa and parts of the Middle East. The objective of this study was to assess the functionality, in barley, of cloned wheat Sr genes effective against race TTKSK. Sr22, Sr33, Sr35 and Sr45 were transformed into barley cv. Golden Promise using Agrobacterium-mediated transformation. All four genes were found to confer effective Stem Rust resistance. The barley transgenics remained susceptible to the barley leaf Rust pathogen Puccinia hordei, indicating that the resistance conferred by these wheat Sr genes was specific for Pgt. Furthermore, these transgenic plants did not display significant adverse agronomic effects in the absence of disease. Cloned Sr genes from wheat are therefore a potential source of resistance against wheat Stem Rust in barley.

  • Stem Rust resistance in wheat is suppressed by a subunit of the mediator complex
    Nature communications, 2020
    Co-Authors: Colin W. Hiebert, Matthew N Rouse, Matthew J. Moscou, Tim Hewitt, Burkhard Steuernagel, Inma Hernández-pinzón, Phon Green, Vincent Pujol, Peng Zhang, Yue Jin
    Abstract:

    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. Here we identify SuSr-D1 by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of Stem Rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation in med15b.D mutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to Stem Rust. Suppression is a common phenomenon and this study provides novel insight into suppression of Rust resistance in wheat.

  • the wheat sr22 sr33 sr35 and sr45 genes confer resistance against Stem Rust in barley
    bioRxiv, 2018
    Co-Authors: Asyraf Md M Hatta, Burkhard Steuernagel, Ryan Johnson, Oadi Matny, Mark A Smedley, Soma Chakraborty, Dhara Bhatt, Xiaodi Xia, Sanu Arora, Teresa Richardson
    Abstract:

    In the last 20 years, Stem Rust caused by the fungus Puccinia graminis f. sp. tritici (Pgt), has re-emerged as a major threat to wheat and barley cultivation in Africa and Europe. In contrast to wheat with 82 designated Stem Rust (Sr) resistance genes, barley's genetic variation for Stem Rust resistance is very narrow with only seven resistance genes genetically identified. Of these, only one locus consisting of two genes is effective against Ug99, a strain of Pgt which emerged in Uganda in 1999 and has since spread to much of East Africa and parts of the Middle East. The objective of this study was to assess the functionality, in barley, of cloned wheat Sr genes effective against Ug99. Sr22, Sr33, Sr35 and Sr45 were transformed into barley cv. Golden Promise using Agrobacterium-mediated transformation. All four genes were found to confer effective Stem Rust resistance. The barley transgenics remained susceptible to the barley leaf Rust pathogen Puccinia hordei, indicating that the resistance conferred by these wheat Sr genes was specific for Pgt. Cloned Sr genes from wheat are therefore a potential source of resistance against wheat Stem Rust in barley.

  • Discovery and characterization of two new Stem Rust resistance genes in Aegilops sharonensis
    TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik, 2017
    Co-Authors: Nicolas Champouret, Matthew J. Moscou, Burkhard Steuernagel, Pablo D. Olivera, Jamie Simmons, Cole Williams, Ryan Johnson, Inmaculada Hernández-pinzón, Phon Green
    Abstract:

    Key message We identified two novel wheat Stem Rust resistance genes, Sr-1644-1Sh and Sr-1644-5Sh in Aegilops sharonensis that are effective against widely virulent African races of the wheat Stem Rust pathogen.

Colin W. Hiebert - One of the best experts on this subject based on the ideXlab platform.

  • Stem Rust resistance in wheat is suppressed by a subunit of the mediator complex
    Nature communications, 2020
    Co-Authors: Colin W. Hiebert, Matthew N Rouse, Matthew J. Moscou, Tim Hewitt, Burkhard Steuernagel, Inma Hernández-pinzón, Phon Green, Vincent Pujol, Peng Zhang, Yue Jin
    Abstract:

    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. Here we identify SuSr-D1 by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of Stem Rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation in med15b.D mutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to Stem Rust. Suppression is a common phenomenon and this study provides novel insight into suppression of Rust resistance in wheat.

  • Pyramiding Stem Rust resistance genes to race TTKSK (Ug99) in wheat
    Canadian Journal of Plant Pathology, 2019
    Co-Authors: Bo Zhang, Colin W. Hiebert, Tom Fetch, Brent Mccallum, Dawn Chi, Allen Xue, Wenguang Cao, R. M. Depauw, George Fedak
    Abstract:

    AbstractThere has not been a major wheat Stem Rust epidemic in Canada since 1954. The detection of race TTKSK, with virulence to Sr31 and most other Stem Rust resistance genes in wheat, presents a ...

  • pyramiding Stem Rust resistance genes to race ttksk ug99 in wheat
    Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2019
    Co-Authors: Bo Zhang, Colin W. Hiebert, Brent Mccallum, Dawn Chi, Wenguang Cao, R. M. Depauw, T Fetch, A G Xue, George Fedak
    Abstract:

    There has not been a major wheat Stem Rust epidemic in Canada since 1954. The detection of race TTKSK, with virulence to Sr31 and most other Stem Rust resistance genes in wheat, presents a threat t...

  • Major gene for field Stem Rust resistance co-locates with resistance gene Sr12 in 'thatcher' wheat
    PLoS ONE, 2016
    Co-Authors: Colin W. Hiebert, Matthew N Rouse, Curt A. Mccartney, Tom Fetch, Harbans Bariana, James A. Kolmer, Jordan Briggs, Frédéric Choulet, Wolfgang Spielmeyer
    Abstract:

    Stem Rust, caused by Puccinia graminis (Pgt), is a damaging disease of wheat that can be controlled by utilizing effective Stem Rust resistance genes. ` Thatcher' wheat carries complex resistance to Stem Rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in ` Thatcher' and look for genetic interactions with Lr34. A RIL population was tested for Stem Rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced Stem Rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in Stem Rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field Stem Rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for ` Thatcher'-derived APR in several environments and this resistance was enhanced in the presence of Lr34.

  • Stem Rust Resistance: Two Approaches
    Advances in Wheat Genetics: From Genome to Field, 2015
    Co-Authors: Colin W. Hiebert, Wolfgang Spielmeyer, Curt A. Mccartney, Mulualem T. Kassa, Tom Fetch, Frank M. You, James G. Menzies, Gavin Humphreys, Brent Mccallum
    Abstract:

    Stem Rust, caused by Puccinia graminis f.sp. tritici (Pgt), is a destructive disease of wheat that has historically caused significant yield losses in much of the global wheat production area. Over the past 50 years, Stem Rust has been effectively controlled by deploying cultivars carrying Stem Rust resistance (Sr) genes. With the emergence of new Pgt races, namely Ug99 and its variants, there has been a reinvestment in Stem Rust research. This includes discovery, characterization, genetic mapping, and cloning of Sr genes. Here we investigated two such examples of genetic characterization and mapping of Stem Rust resistance. In the first example, a region on chromosome 6DS harbouring resistance to Ug99 was examined in several populations and from several sources. In the second example, a less typical genetic model of resistance was studied in which seedling resistance was activated by an independent locus exhibiting an apparent “nonsuppressing” effect. The knowledge gained by these and other lines of research will contribute to the goal of durable resistance to Stem Rust.

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