The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
M. D. Azevedo - One of the best experts on this subject based on the ideXlab platform.
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Occurrence of Puccinia graminis subsp. graminicola in Chewings fescue in Oregon
Plant Disease, 1995Co-Authors: R. E. Welty, M. D. AzevedoAbstract:Welty, R. E., and Azevedo, M. D. 1995. Occurrence of Puccinia graminis subsp. graminicola in Chewings fescue in Oregon. Plant Dis. 79:1014-1016. Stem rust was found on Chewings fescue throughout seed production areas of the Willamette Valley of Oregon in 1993. Stem rust developed in greenhouse-grown seedlings of cultivar Jamestown when inoculated with isolates of stem rust collected from three locations in the Willamette Valley. No difference in plant response was observed among isolates. Twelve cultivars of Chewings fescue and four other species of cool season grasses used for turf (red fescue, tall fescue, sheep fescue, and perennial ryegrass) were inoculated with the same mixture of isolates of stem rust and incubated for infection in a controlled environment chamber. Among the cultivars of Chewings fescue inoculated, stem rust pustules developed on 624 of 673 seedlings; 49 seedlings remained free of stem rust. This is believed to be the first report of Puccinia graminis subsp. graminicola on Chewings fescue in Oregon. Puccinia g. subsp. graminicola infected 28 of 60 seedlings of red fescue, which was less susceptible than Chewings fescue. Five of 46 seedlings of sheep fescue and one of 60 seedlings of perennial ryegrass became infected by P g. subsp. graminicola. Pustules of stem rust did not develop in tall fescue inoculated with this collection of isolates.
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Response of field-grown tall fescue infected by Acremonium coenophialum to Puccinia graminis subsp. graminicola
Plant Disease, 1993Co-Authors: R. E. Welty, R. E. Barker, M. D. AzevedoAbstract:Plants of tall fescue cultivar Kentucky 31 infected (E+) or not infected (E-) by the endophyte Acremonium coenophialum were evaluated for reaction to Puccinia graminis subsp. graminicola for 2 yr in field plots. Stem rust was assessed on the modified Cobb scale on five dates in 1991 and three dates in 1992. On each date, stem rust severity in susceptible plants of Kentucky 31 was similar for E+ and E- plants. On the final assessment in both years, the number of plants without stem rust (0% infection) was similar for E+ and E- plants. Based on these results, the presence of A. coenophialum in plants of Kentucky 31 did not influence stem rust severity or the number of stem rust-resistant plants (.)
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Reaction of tall fescue infected and noninfected by Acremonium coenophialum ot Puccinia graminis subsp. graminicola
Plant Disease, 1991Co-Authors: R. E. Welty, R. E. Barker, M. D. AzevedoAbstract:Seedlings of the tall fescue cultivar Kentucky 31 infected or not infected by the endophyte Acremonium coenophialum were evaluated for reaction to Puccinia graminis subsp. graminicola in the greenhouse. Seedlings (11 wk old) were rated for rust infection type (O-4 scale) 2 wk after inoculation with urediniospores. Seedlings rated 0 or 1 were considered resistant and those rated >1, susceptible; 27% of the infected and 19% of the noninfected seedlings were resistant
R. E. Welty - One of the best experts on this subject based on the ideXlab platform.
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Occurrence of Puccinia graminis subsp. graminicola in Chewings fescue in Oregon
Plant Disease, 1995Co-Authors: R. E. Welty, M. D. AzevedoAbstract:Welty, R. E., and Azevedo, M. D. 1995. Occurrence of Puccinia graminis subsp. graminicola in Chewings fescue in Oregon. Plant Dis. 79:1014-1016. Stem rust was found on Chewings fescue throughout seed production areas of the Willamette Valley of Oregon in 1993. Stem rust developed in greenhouse-grown seedlings of cultivar Jamestown when inoculated with isolates of stem rust collected from three locations in the Willamette Valley. No difference in plant response was observed among isolates. Twelve cultivars of Chewings fescue and four other species of cool season grasses used for turf (red fescue, tall fescue, sheep fescue, and perennial ryegrass) were inoculated with the same mixture of isolates of stem rust and incubated for infection in a controlled environment chamber. Among the cultivars of Chewings fescue inoculated, stem rust pustules developed on 624 of 673 seedlings; 49 seedlings remained free of stem rust. This is believed to be the first report of Puccinia graminis subsp. graminicola on Chewings fescue in Oregon. Puccinia g. subsp. graminicola infected 28 of 60 seedlings of red fescue, which was less susceptible than Chewings fescue. Five of 46 seedlings of sheep fescue and one of 60 seedlings of perennial ryegrass became infected by P g. subsp. graminicola. Pustules of stem rust did not develop in tall fescue inoculated with this collection of isolates.
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Response of field-grown tall fescue infected by Acremonium coenophialum to Puccinia graminis subsp. graminicola
Plant Disease, 1993Co-Authors: R. E. Welty, R. E. Barker, M. D. AzevedoAbstract:Plants of tall fescue cultivar Kentucky 31 infected (E+) or not infected (E-) by the endophyte Acremonium coenophialum were evaluated for reaction to Puccinia graminis subsp. graminicola for 2 yr in field plots. Stem rust was assessed on the modified Cobb scale on five dates in 1991 and three dates in 1992. On each date, stem rust severity in susceptible plants of Kentucky 31 was similar for E+ and E- plants. On the final assessment in both years, the number of plants without stem rust (0% infection) was similar for E+ and E- plants. Based on these results, the presence of A. coenophialum in plants of Kentucky 31 did not influence stem rust severity or the number of stem rust-resistant plants (.)
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Reaction of tall fescue infected and noninfected by Acremonium coenophialum ot Puccinia graminis subsp. graminicola
Plant Disease, 1991Co-Authors: R. E. Welty, R. E. Barker, M. D. AzevedoAbstract:Seedlings of the tall fescue cultivar Kentucky 31 infected or not infected by the endophyte Acremonium coenophialum were evaluated for reaction to Puccinia graminis subsp. graminicola in the greenhouse. Seedlings (11 wk old) were rated for rust infection type (O-4 scale) 2 wk after inoculation with urediniospores. Seedlings rated 0 or 1 were considered resistant and those rated >1, susceptible; 27% of the infected and 19% of the noninfected seedlings were resistant
Brian J Steffenson - One of the best experts on this subject based on the ideXlab platform.
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identification of candidate susceptibility genes to Puccinia graminis f sp tritici in wheat
bioRxiv, 2021Co-Authors: Eva Henningsen, Rafael Della Coletta, Jean Michel Michno, E Gilbert, Marisa E Miller, Chad L Myers, Sean P Gordon, John P Vogel, Brian J SteffensonAbstract:Wheat stem rust disease caused by Puccinia graminis f. sp. tritici (Pgt) is a global threat to wheat production. Fast evolving populations of Pgt limit the efficacy of plant genetic resistance and constrain disease management strategies. Understanding molecular mechanisms that lead to rust infection and disease susceptibility could deliver novel strategies to deploy crop resistance through genetic loss of disease susceptibility. We used comparative transcriptome-based and orthology-guided approaches to characterize gene expression changes associated with Pgt infection in susceptible and resistant Triticum aestivum genotypes as well as the non-host Brachypodium distachyon. We targeted our analysis to genes with differential expression in T. aestivum and genes suppressed or not affected in B. distachyon and report several processes potentially linked to susceptibility to Pgt, such as cell death suppression and impairment of photosynthesis. We complemented our approach with a gene co-expression network analysis to identify wheat targets to deliver resistance to Pgt through removal or modification of putative susceptibility genes.
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concerted action of two avirulent spore effectors activates reaction to Puccinia graminis 1 rpg1 mediated cereal stem rust resistance
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Jayaveeramuthu Nirmala, Scot H. Hulbert, Les J. Szabo, Tom Drader, Paulraj K Lawrence, Camille M Steber, Brian J Steffenson, Diter Von Wettstein, A KleinhofsAbstract:The barley stem rust resistance gene Reaction to Puccinia graminis 1 (Rpg1), encoding a receptor-like kinase, confers durable resistance to the stem rust pathogen Puccinia graminis f. sp. tritici. The fungal urediniospores form adhesion structures with the leaf epidermal cells within 1 h of inoculation, followed by hyphae and haustorium formation. The RPG1 protein is constitutively expressed and not phosphorylated. On inoculation with avirulent urediniospores, it is phosphorylated in vivo within 5 min and subsequently degraded. Application of arginine-glycine-aspartic acid peptide loops prevented the formation of adhesion structures for spore attachment, the phosphorylation of RPG1, and germination of the viable spores. Arginine-glycine-aspartic acid affinity chromatography of proteins from the ungerminated avirulent rust spores led to the purification and identification of a protein with fibronectin type III and breast cancer type 1 susceptibility protein domains and a vacuolar protein sorting-associated protein 9 with a coupling of ubiquitin to endoplasmic reticulum degradation domain. Both proteins are required to induce in vivo phosphorylation and degradation of RPG1. Combined application of both proteins caused hypersensitive reaction on the stem rust-resistant cultivar Morex but not on the susceptible cultivar Steptoe. Expression studies indicated that mRNA of both genes are present in ungerminated urediniospores and are constitutively transcribed in sporelings, infected leaves, and haustoria in the investigated avirulent races. Evidence is presented that RPG1, in yeast, interacts with the two protein effectors from the urediniospores that activate cooperatively the stem rust resistance protein RPG1 long before haustoria formation.
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Reaction of barley seedlings with different stem rust resistance genes to Puccinia graminis f. sp. tritici and Puccinia graminis f. sp. secalis
Canadian Journal of Plant Pathology, 2005Co-Authors: Y. Sun, Brian J SteffensonAbstract:Seedling tests are desirable for disease resistance screening in breeding programs because a large number of lines can be evaluated in a short period of time and with modest space requirements. This study was undertaken to identify pathotypes of the wheat stem rust pathogen (Puccinia graminis f. sp. tritici) and cultures of the rye stem rust pathogen (Puccinia graminis f. sp. secalis) that might be useful for detecting resistance genes in barley (Hordeum vulgare) at the seedling stage. Barley accessions with different resistance genes (Rpg1, Rpg2, Rpg3, rpg4, and rpgBH) were assessed for their infection types (ITs) to 13 pathotypes of P. graminis f. sp. tritici and two cultures of P. graminis f. sp. secalis at two temperature regimes (18–21 °C and 24–25 °C). The P. graminis f. sp. tritici pathotypes HKHJ and QCCJ were effective for specifically detecting Rpg1 and rpg4, respectively, and will facilitate resistance breeding efforts. No cultures were found to be effective for specifically detecting the resis...
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Sources of resistance to pathotype QCC of Puccinia graminis f.sp. tritici in barley
Crop Science, 1994Co-Authors: Y. Jin, Brian J Steffenson, Thomas FetchAbstract:The occurrence of a wheat stem rust (Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn.) pathotype (Pgt-QCC) with virulence for the Rpg1 gene in barley (Hordeum vulgare L.) necessitated the search for resistant barley germplasm. From preliminary screenings of over 18 000 barley accessions, 13 lines were identified as possessing resistance to pathotype QCC: «Diamond», «Hietpas 5», Q21861, PC 11, PC 84, PC 249, PC 250, CI 5541, PI 452406, PI 452421, PI 477843, PI 477854, and PI 477860. This study was conducted to further characterize the reaction of the selected lines to pathotype QCC
K.w. Buchannon - One of the best experts on this subject based on the ideXlab platform.
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The Reaction of Barley Varieties to Rye Stem Rust, Puccinia graminis Var. Secalis1
Canadian Journal of Agricultural Science, 2016Co-Authors: T. Johnson, K.w. BuchannonAbstract:Indications derived from Uniform Rust Nurseries that a number of barley varieties resistant to wheat stem rust (Puccinia graminis var. tritici) were susceptible to rye stem rust (P. graminis var. secalis) were confirmed by tests made in the greenhouse and in the field. Analyses of stem-rust collections from rust-resistant barley varieties showed these, in most cases, to consist of rye stem rust In determining the reaction of barley varieties to rye stem rust it was found that the reaction of the seedling leaf gave little indication of the reaction of the stem of the adult plant. It was therefore necessary to test plants in the adult stage to determine varietal reaction to the rust Out of 270 barley accessions tested in this way only one showed high resistance to rye stem rust. It is concluded that while rye stem rust is not a threat to barley production at present it is a potential danger that should not be ignored
T. Johnson - One of the best experts on this subject based on the ideXlab platform.
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The Reaction of Barley Varieties to Rye Stem Rust, Puccinia graminis Var. Secalis1
Canadian Journal of Agricultural Science, 2016Co-Authors: T. Johnson, K.w. BuchannonAbstract:Indications derived from Uniform Rust Nurseries that a number of barley varieties resistant to wheat stem rust (Puccinia graminis var. tritici) were susceptible to rye stem rust (P. graminis var. secalis) were confirmed by tests made in the greenhouse and in the field. Analyses of stem-rust collections from rust-resistant barley varieties showed these, in most cases, to consist of rye stem rust In determining the reaction of barley varieties to rye stem rust it was found that the reaction of the seedling leaf gave little indication of the reaction of the stem of the adult plant. It was therefore necessary to test plants in the adult stage to determine varietal reaction to the rust Out of 270 barley accessions tested in this way only one showed high resistance to rye stem rust. It is concluded that while rye stem rust is not a threat to barley production at present it is a potential danger that should not be ignored
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The Production by Puccinia graminis of Abortive Pycnia on Wheat1
Canadian Journal of Agricultural Science, 2016Co-Authors: T. Johnson, G. J. GreenAbstract:In infection experiments with a culture of race 59 of Puccinia graminis Pers f sp tritici Erikss and Henn, involving the infection of barberry and the subsequent inoculation of wheat seedlings with the aeciospores, it was observed that whereas some of the infections on wheat produced uredia others produced abortive pycnia Paraphyses were present as in pycnia on barberry and a scanty exudate was produced but no pycniospores were present in it.
