A Fungal Elicitor of the Resistance Response in Wheat

1985 ◽  
Vol 40 (9-10) ◽  
pp. 743-744 ◽  
Author(s):  
Karl-Heinz Kogel ◽  
Birgit Heck ◽  
Gerd Kogel ◽  
Bruno Moerschbacher ◽  
Hans-Joachim Reisener
Keyword(s):  
Stem Rust ◽  
Active Compound ◽  
Germ Tube ◽  
Phenylpropanoid Pathway ◽  
Metabolic Changes ◽  
Fungal Elicitor ◽  
Wheat Stem Rust ◽  
Mesophyll Cells ◽  
Resistance Response ◽  
Wheat Leaves

Abstract An elicitor of the lignification response in wheat leaves was isolated from the germ-tube walls of wheat stem rust. The active compound causes metabolic changes typically correlated with the resistance response, i.e. the formation of lignin or lignin-like polymers in affected epidermal and mesophyll cells and the increased activities of enzymes involved in the phenylpropanoid-pathway.

scholarly journals Phenotypes Conferred by Wheat Multiple Pathogen Resistance Locus, Sr2, Include Cell Death in Response to Biotic and Abiotic Stresses

2019 ◽  
Vol 109 (10) ◽  
pp. 1751-1759
Author(s):  
Linda Tabe ◽  
Sharon Samuel ◽  
Matthew Dunn ◽  
Rosemary White ◽  
Rohit Mago ◽  
...  
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Stem Rust ◽  
Abiotic Stresses ◽  
Resistance Locus ◽  
Petroleum Jelly ◽  
Wheat Stem Rust ◽  
Mesophyll Cells ◽  
Rust Infection ◽  
Photosynthetic Cells

The wheat Sr2 locus confers partial resistance to four biotrophic pathogens: wheat stem rust (Puccinia graminis f. sp. tritici), leaf rust (P. triticina), stripe rust (P. striiformis f. sp. tritici), and powdery mildew (Blumeria graminis f. sp. tritici). In addition, Sr2 is linked with a brown coloration of ears and stems, termed pseudo-black chaff (PBC). PBC, initially believed to be elicited by stem rust infection, was subsequently recognized to occur in the absence of pathogen infection. The current study demonstrates that the resistance response to stem rust is associated with the death of photosynthetic cells around rust infection sites in the inoculated leaf sheath. Similarly, Sr2-dependent resistance to powdery mildew was associated with the death of leaf mesophyll cells around mildew infection sites. We demonstrate that PBC occurring in the absence of pathogen inoculation also corresponds with death and the collapse of photosynthetic cells in the affected parts of stems and ears. In addition, Sr2-dependent necrosis was inducible in leaves by application of petroleum jelly or by heat treatments. Thus, Sr2 was found to be associated with cell death, which could be triggered by either biotic or abiotic stresses. Our results suggest a role for the Sr2 locus in controlling cell death in response to stress.

Sterols of healthy and rust-infected primary leaves of wheat and of non-germinated and germinated uredospores of wheat stem rust

1972 ◽  
Vol 50 (1) ◽  
pp. 185-190 ◽  
Author(s):  
R. Nowak ◽  
W. K. Kim ◽  
R. Rohringer
Keyword(s):  
Thin Layer ◽  
Stem Rust ◽  
Total Sterol ◽  
Sterol Content ◽  
Wheat Stem Rust ◽  
Resistant Lines ◽  
Wheat Leaves

Sterols extracted from healthy and rust-infected primary leaves of wheat or from non-germinated and germinated uredospores of stem rust were analyzed by thin-layer, column, and gas–liquid chromatography.Wheat leaves of susceptible and resistant lines contained cholesterol, campesterol, stigmasterol, β-sitosterol, and an unknown sterol that accounted for 75% to 80% of total sterol content. A further sterol, stigmast-7-enol, occurred in all rust-infected leaves and in 1 of 11 samples of healthy leaves. Sterol levels were not related to susceptibility or resistance. The level of stigmast-7-enol in infected leaves appeared to be correlated with the amount of fungal mass in the host.Uredospores of stem rust contained trace amounts of an unknown sterol, cholesterol, and either ergost-7-enol or stigmasterol, and larger amounts of stigmast-7-enol. After germination, the level of cholesterol increased, especially in differentiating uredosporelings. The level of stigmast-7-enol tended to decrease after germination.Sterol fractions from wheat leaves (healthy and rust-infected) and from stem rust uredospores (non-germinated and germinated) were not phytotoxic. They did not inhibit rust development in susceptible leaves nor did they promote it in resistant leaves.

THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: XVIII. DISTRIBUTION OF TRITIUM-LABELLED CYTIDINE, URIDINE, AND LEUCINE IN WHEAT LEAVES INFECTED WITH THE STEM RUST FUNGUS

1967 ◽  
Vol 45 (5) ◽  
pp. 555-563 ◽  
Author(s):  
P. K. Bhattacharya ◽  
Michael Shaw
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Host Cells ◽  
Fungal Mycelium ◽  
Puccinia Graminis ◽  
Mesophyll Cells ◽  
Wheat Leaves ◽  
Host Parasite

Wheat leaves were detached 6 days after inoculation with the stem rust fungus (Puccinia graminis var. tritici Erikss. and Henn.) and fed with tritiated leucine, cytidine, uridine, or thymidine. Mesophyll cells in infected zones incorporated more leucine into protein and more cytidine and uridine into RNA than did cells in adjacent uninfected tissue. Leucine, cytidine, and uridine were also heavily incorporated by fungal mycelium and developing uredospores. Grain counts over host nuclei in the infected zone were two to three-fold of those over nuclei in adjacent uninfected zones. There was no detectable incorporation of thymidinemethyl-3H into either the fungus or the host cells. The results are 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.

AN ELECTRON MICROSCOPE STUDY OF INTRAVACUOLAR BODIES IN THE UREDIA OF WHEAT STEM RUST AND IN HYPHAE OF OTHER FUNGI

1967 ◽  
Vol 45 (9) ◽  
pp. 1473-1478 ◽  
Author(s):  
P. L. Thomas ◽  
P. K. Isaac
Keyword(s):  
Electron Microscope ◽  
Internal Structure ◽  
Stem Rust ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Osmium Tetroxide ◽  
Wheat Stem Rust ◽  
Wheat Leaves

An electron microscope study of plant and fungal specimens fixed in a mixture of glutaraldehyde and acrolein followed by osmium tetroxide showed intravacuolar bodies with an intricate internal structure ranging from myelin-like membranes to a system of tubules. The bodies were commonly found in the developing uredia of stem rust infected wheat leaves and in the hyphae of several species of fungi. The origin and nature of the bodies is discussed.

METABOLIC CHANGES IN DETACHED WHEAT LEAVES FLOATED ON BENZIMIDAZOLE AND THE EFFECT OF THESE CHANGES ON RUST REACTION

1958 ◽  
Vol 36 (5) ◽  
pp. 591-601 ◽  
Author(s):  
D. J. Samborski ◽  
F. R. Forsyth ◽  
Clayton Person
Keyword(s):  
Stem Rust ◽  
Metabolic Changes ◽  
Soluble Carbohydrate ◽  
Soluble Nitrogen ◽  
Progressive Decrease ◽  
Detached Leaves ◽  
Endogenous Substrate ◽  
Wheat Leaves

Stem-rust-infected leaves of resistant (var. Khapli) and susceptible (var. Little Club) wheats were detached and floated on water and benzimidazole, with and without glucose. Khapli leaves were susceptible on water, resistant on 40 p.p.m. benzimidazole, susceptible on 40 p.p.m. benzimidazole with 1% glucose, and resistant on 60 p.p.m. benzimidazole with 1% glucose. Little Club leaves were susceptible in all treatments. Khapli leaves subjected to treatments that increase the endogenous substrate levels, such as floating on water for 2 to 4 days or spraying with DDT 2 or 3 days before detachment, were susceptible on 40 p.p.m. benzimidazole and resistant or partially resistant at higher concentrations.The progressive decrease in protein of detached leaves on water was interrupted on transfer to benzimidazole, after which some resynthesis of protein took place with a corresponding decrease in the soluble nitrogen fraction. Detached leaves on benzimidazole with 1% glucose had more soluble nitrogen than leaves on benzimidazole alone. There was more alcohol-soluble carbohydrate in leaves floated on water than in leaves on benzimidazole.

Electron microscopy of susceptible and resistant near-isogenic (sr6/Sr6) lines of wheat infected by Puccinia graminis tritici. III. Ultrastructure of incompatible interact

1979 ◽  
Vol 57 (23) ◽  
pp. 2626-2634 ◽  
Author(s):  
D. E. Harder ◽  
D. J. Samborski ◽  
R. Rohringer ◽  
S. R. Rimmer ◽  
W. K. Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Stem Rust ◽  
Stem Rust Resistance ◽  
Temperature Sensitive ◽  
Puccinia Graminis ◽  
Cell Necrosis ◽  
Mitochondrial Membranes ◽  
Wheat Stem Rust ◽  
Mesophyll Cells ◽  
Mother Cells

The interaction between avirulent wheat stem rust and wheat mesophyll cells containing the temperature-sensitive Sr6 gene for stem rust resistance was studied by electron microscopy. Mesophyll cells that were invaded at 26 °C (conditioning compatibility) did not develop any signs of incompatibility after they were transferred to 19 °C, at which temperature incompatibility is normally expressed. In host tissue that appeared to be invaded after the change from 26 to 19 °C, the early ultrastructural symptoms of incompatibility were a more electron-dense and often perforated invaginated host plasmalemma, disruptions of the noninvaginated host plasmalemma, vacuolation of the cytoplasm, and accumulations of electron-dense material along the membranes of the vacuoles. At later stages in the development of incompatible interactions, the electron-dense accumulations along the vacuole membranes increased in size and occurred along chloroplast and mitochondrial membranes. Eventually, the entire protoplasts were electron dense and collapsed. In haustoria and haustorial mother cells, incompatibility was usually expressed by a uniform increase in electron density of the cytoplasm. In the Sr6/P6 interaction at 19 °C, host cell necrosis was not always accompanied by fungal necrosis or vice versa. In Sr5/P5 interactions, which were examined for comparison, the intracellular symptoms of incompatibility were similar to those of the Sr6/P6 interactions.

scholarly journals Differences in the Methyl Ester Distribution of Homogalacturonans from Near-Isogenic Wheat Lines Resistant and Susceptible to the Wheat Stem Rust Fungus

2003 ◽  
Vol 16 (10) ◽  
pp. 945-952 ◽  
Author(s):  
Nicola Wiethölter ◽  
Barbara Graeßner ◽  
Manfred Mierau ◽  
Andrew J. Mort ◽  
Bruno M. Moerschbacher
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Methyl Esters ◽  
Resistance Mechanisms ◽  
Wheat Cultivars ◽  
Wheat Stem Rust ◽  
Significant Difference ◽  
The Difference ◽  
Wheat Leaves ◽  
Wheat Lines

Plants possess an efficient nonself surveillance system triggering induced disease resistance mechanisms upon molecular recognition of microbial invaders. Successful pathogens have evolved strategies to evade or counteract these mechanisms, e.g., by the generation of suppressors. Pectic fragments produced during host cell wall degradation can act as endogenous suppressors of the hypersensitive response in wheat leaves. We have isolated and characterized ho-mogalacturonans from cell walls of two wheat cultivars susceptible to the stem rust fungus, Puccinia graminis f. sp. tritici, namely cvs. Prelude and Marquis, and from near-isogenic lines of both cultivars containing the Sr5-gene for hypersensitive rust resistance. Two independent approaches were used to compare their methyl esterification: i) immunochemistry using the monoclonal antibodies JIM5, JIM7, PAM1, and LM7 and ii) chromatography of oligogalacturonides representing stretches of contiguous nonmethyl-esterified GalA residues. The results clearly indicate a significant difference in the homogalacturonans from susceptible and resistant wheat lines. The difference can best be explained by assuming a nonrandom and more blockwise distribution of the methyl esters in the homoga-lacturonans of susceptible wheat cultivars as compared with a presumably more random distribution in the near-isogenic resistant lines. Possible consequences of this difference for the enzymatic generation of endogenous suppressors are discussed.

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