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.

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.

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.

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.

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: IV. THE EFFECT OF MALEIC HYDRAZIDE AND INDOLEACETIC ACID ON THE RUST RESISTANCE OF KHAPLI AND LITTLE CLUB WHEATS

1957 ◽  
Vol 35 (4) ◽  
pp. 449-455 ◽  
Author(s):  
D. J. Samborski ◽  
Michael Shaw
Keyword(s):  
Growth Inhibition ◽  
Stem Rust ◽  
Rust Resistance ◽  
Indoleacetic Acid ◽  
Maleic Hydrazide ◽  
Sand Culture ◽  
Simultaneous Application ◽  
Reaction Type ◽  
Host Parasite

Little Club (rust reaction type 4) and Khapli (rust reaction type 1 with race 15B) wheats were grown in sand culture in 1-qt. crocks or 5-in. pots. Daily applications of maleic hydrazide or indoleacetic acid were started 5 days before (10 days after sowing), on the day of, and 5 days after inoculation with stem rust (Race 15B) and were continued for about three weeks. Maleic hydrazide inhibited growth and, at 5 and 10 mg. per pot, flowering. Type 4 pustules developed on Khapli plants treated with 5 and 10 mg. of maleic hydrazide daily from the 5th day before and from the day of inoculation. Indoleacetic acid (0.5 mg. per pot from the 10th day after sowing) stimulated growth and flowering and slightly increased the resistance of Khapli. Treatments started 5 days after inoculation had no effect on rust development on Khapli, and none of the treatments altered the rust reaction of Little Club. Spores produced on plants treated with maleic hydrazide gave normal rust reactions on untreated plants.The effect of maleic hydrazide on the plants and on rust development was not altered by the simultaneous application of uracil, which reversed the growth inhibition caused by thiouracil. Thiouracil inhibited rust development in the presence of maleic hydrazide.

THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: XIII. THE EFFECT OF STEM RUST ON PURINES IN WHEAT LEAVES

1964 ◽  
Vol 42 (2) ◽  
pp. 139-144 ◽  
Author(s):  
Michael Shaw ◽  
B. I. Sahai Srivastava
Keyword(s):  
Copper Oxide ◽  
Perchloric Acid ◽  
Stem Rust ◽  
Puccinia Graminis ◽  
Puccinia Graminis Tritici ◽  
Detached Leaves ◽  
Wheat Leaves ◽  
Host Parasite

The purines were precipitated from alcohol extracts of Little Club wheat with copper oxide or absorbed from perchloric acid extracts with Norit A. Guanine, adenine, and an unidentified purine were isolated from seedlings germinated in darkness and from the tops of young plants grown in the greenhouse. Adenine and the unidentified purine were present in much larger amounts than guanine. The concentrations of adenine and the unidentified purine in the first seedling leaves were increased approximately four- and five-fold by infection with Puccinia graminis tritici Erikss. and Henn. No evidence was obtained for the presence of any purine or purine-like substance in uninfected or infected leaves which would delay senescence in detached leaves as do kinetin, benzimidazole, and purine-like substances present in coconut endosperm.

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