STUDIES ON THE POLYPHENOL–POLYPHENOLOXIDASE SYSTEM OF WHEAT STEM RUST UREDOSPORES

1959 ◽  
Vol 5 (1) ◽  
pp. 37-46 ◽  
Author(s):  
G. L. Farkas ◽  
G. A. Ledingham
Keyword(s):  
Stem Rust ◽  
Surrounding Medium ◽  
Quinone Reductase ◽  
Infection Process ◽  
Phenol Oxidation ◽  
Oxidation Products ◽  
Toxicity Tests ◽  
Toxic Substances ◽  
Wheat Stem Rust ◽  
Host Parasite

The presence of a polyphenoloxidase in wheat stem rust uredospores has been demonstrated. The enzyme was released by the germinating spores together with phenolic substrates, resulting in the formation of phenol oxidation products in the surrounding medium. The substrate specificity of the enzyme was investigated, and gallic acid was found to give an unusually high oxidation rate. Pyrogallic acid and catechol were also rapidly oxidized. Toxicity tests have been carried out with phenol oxidation products on germinating spores and it has been shown that toxicity depends on the stage of oxidation. Short-term oxidations led to the formation of highly toxic compounds; longer periods of oxidation converted these into harmless products, whereas very long periods of oxidation resulted again in the production of toxic substances. The spores also contained a quinone reductase which apparently holds the phenolics in a reduced state until they are released during germination or during the infection process. The possible role of the phenol – phenoloxidase – quinone reductase system in the host–parasite relations of the wheat – stem rust complex is discussed.

THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: X. THE METABOLISM OF INDOLEACETIC ACID-1-C14 BY WHEAT AND OAT COLEOPTILE SECTIONS, UNINFECTED AND RUSTED WHEAT LEAVES AND UREDOSPORES OF WHEAT STEM RUST

1962 ◽  
Vol 40 (3) ◽  
pp. 511-521 ◽  
Author(s):  
B. I. Sahai Srivastava ◽  
Michael Shaw ◽  
R. J. Woods
Keyword(s):  
Stem Rust ◽  
Indoleacetic Acid ◽  
Water Soluble ◽  
Wheat Stem Rust ◽  
Resistant Species ◽  
Metabolic Products ◽  
Soluble Compound ◽  
Wheat Leaves ◽  
Insoluble Compounds ◽  
Host Parasite

Coleoptiles of Little Club wheat and Brighton oats, uninfected and rusted leaves of Little Club and Khapli wheats and uredospores of stem rust were incubated with 10 or 100 parts per million of indoleacetate-C14OOK (IAA) in distilled water in darkness. The metabolic products formed were extracted by boiling the incubation medium. This was then partitioned with ether and the aqueous and ether fractions were analyzed by paper chromatography. In the coleoptiles and uninfected and rusted wheat leaves 8–14 different Ehrlich- or Salkowski-positive radioactive products of IAA metabolism were detected. These were not found when the plant material was incubated with water alone. One ether-soluble compound, and four ether-insoluble compounds from wheat coleoptiles had ultraviolet spectra of the indole type and were found to be active in the Avena straight growth test. IAA and its ether-soluble products disappeared more rapidly from uninfected than from rust-infected Little Club wheat leaves. Four water-soluble, radioactive products were found in uninfected leaves but only two in rusted leaves. A substance tentatively identified as indolecarboxylic acid (ICA) was not found in Little Club wheat leaves until 16 days after rust infection, but was present in both uninfected and infected leaves of the resistant species, Khapli. Uredospores apparently converted IAA only to nonradioactive decarboxylation products, tentatively identified as ICA and indolealdehyde. The results are discussed and attention is drawn to the importance of ether-insoluble products of IAA metabolism.

scholarly journals Unraveling the Wheat Stem Rust Infection Process on Barley Genotypes Through Relative qPCR and Fluorescence Microscopy

2015 ◽  
Vol 105 (5) ◽  
pp. 707-712 ◽  
Author(s):  
J. D. Zurn ◽  
S. Dugyala ◽  
P. Borowicz ◽  
R. Brueggeman ◽  
M. Acevedo
Keyword(s):  
Fluorescence Microscopy ◽  
Stem Rust ◽  
Rating Scale ◽  
Infection Type ◽  
Infection Process ◽  
Qpcr Assay ◽  
Wheat Stem Rust ◽  
Fungal Development ◽  
Rust Infection ◽  
Fungal Dna

The infection process of wheat stem rust (Puccinia graminis f. sp. tritici) on barley (Hordeum vulgare) is often observed as a mesothetic infection type at the seedling stages, and cultivars containing the same major resistance genes often show variation in the level of resistance provided against the same pathogen race or isolate. Thus, robust phenotyping data based on quantification of fungal DNA can improve the ability to elucidate host–pathogen interaction, especially at early time points of infection when disease symptoms are not yet evident. Quantitative real-time polymerase chain reaction (qPCR) was used to determine the amount of fungal DNA relative to host DNA in infected tissue, providing new insights about fungal development and host resistance during the infection process in this pathosystem. The stem rust susceptible ‘Steptoe’, resistant cultivars containing only Rpg1 (‘Beacon’, ‘Morex’, and ‘Chevron’), and the resistant line Q21861 containing Rpg1 and the rpg4/Rpg5 complex were evaluated using the traditional 0-to-4 rating scale, fluorescence microscopy, and qPCR. Statistical differences (P < 0.05) were observed in fungal development as early as 24 h postinoculation using the qPCR assay. Fungal development observed using fluorescence microscopy displayed the same hierarchal ordering observed using the qPCR assay. The fungal development occurring at 24 and 48 h postinoculation was vastly different than what was expected using the traditional disease phenotyping methodology; with Steptoe appearing more resistant than the barley lines harboring the known Rpg1 and rpg4/Rpg5 resistance complex. These data indicate potential early prehaustorial resistance contributions in a cultivar considered susceptible based on infection type. Moreover, the temporal differences in resistance suggest pre- and post-haustorial resistance mechanisms in the barley–wheat stem rust infection process, indicating potential host genotype contributions related to basal defense during the wheat stem rust infection process.

Retrospective analysis of virulence of the North Caucasian population of wheat stem rust pathogen

2019 ◽  
Vol 1 (81) ◽  
pp. 85-90
Author(s):  
Galina Volkova ◽  
◽  
Olesya Miroshnichenko ◽  
Olga Tarancheva ◽  
◽  
...  
Keyword(s):  
Retrospective Analysis ◽  
Stem Rust ◽  
Caucasian Population ◽  
Wheat Stem Rust ◽  
The North ◽  
Rust Pathogen

scholarly journals Field resistance to wheat stem rust in durum wheat ( Triticum turgidum ssp. durum ) accessions deposited at the USDA National Small Grains Collection

Crop Science ◽  
2021 ◽  
Author(s):  
Pablo D. Olivera ◽  
Worku D. Bulbula ◽  
Ayele Badebo ◽  
Harold E. Bockelman ◽  
Erena A. Edae ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Stem Rust ◽  
Triticum Turgidum ◽  
Field Resistance ◽  
Wheat Stem Rust ◽  
Small Grains

scholarly journals Large-Scale Atmospheric Dispersal Simulations Identify Likely Airborne Incursion Routes of Wheat Stem Rust Into Ethiopia

2017 ◽  
Vol 107 (10) ◽  
pp. 1175-1186 ◽  
Author(s):  
M. Meyer ◽  
L. Burgin ◽  
M. C. Hort ◽  
D. P. Hodson ◽  
C. A. Gilligan
Keyword(s):  
Stem Rust ◽  
Large Scale ◽  
Dispersion Model ◽  
Fungal Spores ◽  
Disease Outbreaks ◽  
Particle Dispersion ◽  
East African ◽  
Wheat Stem Rust ◽  
Sub Saharan ◽  
African Rift

In recent years, severe wheat stem rust epidemics hit Ethiopia, sub-Saharan Africa’s largest wheat-producing country. These were caused by race TKTTF (Digalu race) of the pathogen Puccinia graminis f. sp. tritici, which, in Ethiopia, was first detected at the beginning of August 2012. We use the incursion of this new pathogen race as a case study to determine likely airborne origins of fungal spores on regional and continental scales by means of a Lagrangian particle dispersion model (LPDM). Two different techniques, LPDM simulations forward and backward in time, are compared. The effects of release altitudes in time-backward simulations and P. graminis f. sp. tritici urediniospore viability functions in time-forward simulations are analyzed. Results suggest Yemen as the most likely origin but, also, point to other possible sources in the Middle East and the East African Rift Valley. This is plausible in light of available field surveys and phylogenetic data on TKTTF isolates from Ethiopia and other countries. Independent of the case involving TKTTF, we assess long-term dispersal trends (>10 years) to obtain quantitative estimates of the risk of exotic P. graminis f. sp. tritici spore transport (of any race) into Ethiopia for different ‘what-if’ scenarios of disease outbreaks in potential source countries in different months of the wheat season.

THE INHERITANCE OF PATHOGENICITY IN RACES 111 AND 29 OF WHEAT STEM RUST

1969 ◽  
Vol 11 (2) ◽  
pp. 266-274 ◽  
Author(s):  
K. N. Kao ◽  
D. R. Knott
Keyword(s):  
Stem Rust ◽  
Rust Resistance ◽  
Single Gene ◽  
Stem Rust Resistance ◽  
Wheat Stem Rust ◽  
Complementary Genes

The inheritance of pathogenicity in wheat stem rust was studied in selfed cultures of races 29 and 111, F1 and F2 cultures of a cross between the two races and cultures from a backcross to race 29. The various cultures were tested on Marquis and Prelude and on a series of lines of these varieties carrying single genes for stem rust resistance. Virulence on Sr 5, Sr 6, Sr 8, Sr 9a, Sr 14 and a gene in Marquis was recessive and in each case there was a single gene for virulence corresponding to each gene for resistance. Virulence on Sr 1 was possibly controlled by two dominant complementary genes. There appeared to be two alleles for virulence on Prelude, one dominant and one recessive.

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