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. XIX. Further observations on nucleoprotein changes in wheat leaf nuclei during rust infection

1968 ◽  
Vol 46 (1) ◽  
pp. 11-16 ◽  
Author(s):  
P. K. Bhattacharya ◽  
Michael Shaw ◽  
J. M. Naylor
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Puccinia Graminis ◽  
Mesophyll Cells ◽  
Rust Infection ◽  
Puccinia Graminis Tritici ◽  
Wheat Leaf ◽  
Host Parasite

Cytophotometric measurements of DNA (Feulgen) and protein-bound lysine and arginine (fluorodinitrobenzene-Sakaguchi) were made on nuclei in mesophyll cells of infected and uninfected leaves of Little Club wheat at intervals of 2 to 4 days up to 13 days after inoculation with uredospores of race 15B of the stem rust fungus (Puccinia graminis tritici Erikss. and Henn.). No change in host DNA was found within 6 days after inoculation, but there were marked decreases in protein-bound lysine and arginine as early as 2 days after inoculation. The DNA/lysine and DNA/arginine ratios were higher in rust-affected host nuclei, but infection did not alter the ratio of protein-bound lysine to arginine. In another series of measurements it was shown that rust infection caused striking increases in the volume and the RNA and protein contents of host nucleoli. These changes persisted even in advanced infections.All the results are consistent with our earlier observations and indicate that profound changes in nuclear metabolism are induced by infection with the rust fungus.

Development of Cronartium comandrae in Comandra umbellata

1973 ◽  
Vol 51 (7) ◽  
pp. 1369-1372
Author(s):  
F. H. Tainter
Keyword(s):  
Rust Fungus ◽  
Central Core ◽  
Host Cells ◽  
Fungal Mycelium ◽  
Basal Cells ◽  
Intercellular Spaces ◽  
Mesophyll Cells

Infection of bastard toadflax by aeciospores of the comandra rust fungus appeared to occur through stomata. Within 3–4 days substomatal hyphae began ramifying into intercellular spaces between mesophyll cells. On the 5th day small chlorotic spots were visible with a 10 × hand lens and within 9 days, yellow uredial pustules were visible to the unaided eye. Uredia maturation proceeded via a palisade-like arrangement of cells to form basal cells, uredial initials, stalk cells, and urediospores, successively. By the 5th day haustoria began forming and by the 9th day were numerous, developing into a variety of sizes and shapes. Several layers of immature urediospores were also produced. By the 20th day host mesophyll cells became slightly compacted in the vicinity of the pustule and intercellular spaces were packed with fungal mycelium. After 25 days, the host cells in the base of the pustule became visibly disorganized and a central core of hyphae had developed in the base of most pustules, severely misshaping some host cells. Between 25 and 28 days most pustule membranes had ruptured and urediospores were liberated. Telia began to form in the former uredia by the 32nd day after inoculation.

Lomasomes in wheat leaves infected by Puccinia graminis and P. recondita

1968 ◽  
Vol 46 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Mary A. Ehrlich ◽  
John F. Schafer ◽  
Howard G. Ehrlich
Keyword(s):  
Cell Wall ◽  
Host Resistance ◽  
Mesophyll Cell ◽  
Host Cells ◽  
Puccinia Graminis ◽  
Mesophyll Cells ◽  
Dark Staining ◽  
Dark Material ◽  
Wheat Leaves ◽  
Type Infection

Boundary formations (lomasomes) have been observed between the plasmalemma and wall of mesophyll cells in Puccinia graminis and P. recondita infected wheat plants. They were present in host cells from both resistant- and susceptible-type infection centers, and were especially frequent and massive in plants grown at low (65–70 °F) temperatures. They appeared to occur in response to the presence of the pathogen, but did not seem to be associated with either host resistance or susceptibility. The dark-staining masses present in the lomasomes were often dense and extremely irregular in shape, but some of the dark material occasionally appeared vesicular or tubular. The suggestion is made that the lomasomes observed in the present investigation may be associated with infection-induced alterations in the mesophyll cell wall.

Effect of blasticidin S, ethionine, and polyoxin D on stem rust development and host-cell necrosis in wheat near-isogenic for gene Sr6

1977 ◽  
Vol 55 (5) ◽  
pp. 568-573 ◽  
Author(s):  
W. K. Kim ◽  
R. Rohringer ◽  
D. J. Samborski ◽  
N. K. Howes
Keyword(s):  
Host Cell ◽  
Stem Rust ◽  
Fungal Growth ◽  
Triticum Aestivum L ◽  
Hypersensitive Reaction ◽  
Host Cells ◽  
Puccinia Graminis ◽  
Cell Necrosis ◽  
Blasticidin S ◽  
Wheat Leaves

Seedlings of resistant (Sr6) and susceptible (sr6) near-isogenic lines of wheat (Triticum aestivum L.) were inoculated with an avirulent (P6) race of stem rust (Puccinia graminis (Pers.) f.sp. tritici Eriks. & Henn.) and kept for 2 days at 26 °C where the Sr6 gene is ineffective, treated with blasticidin S, ethionine, polyoxin D, or buffer, and transferred to 19 °C where the Sr6 gene is normally effective. One and 2 days later, leaves were stained with Calcofluor and examined by fluorescence microscopy to detect autofluorescing necrotic host cells and Calcofluor-stained stem rust colonies.Blasticidin S was phytotoxic to wheat leaves at concentrations that had no effect on fungal growth during the first 2 days after treatment. At later stages, extensive host necrosis, resulting from the phytotoxicity of this antibiotic, inhibited rust development.Ethionine and polyoxin D strongly inhibited rust development at concentrations that were not phytotoxic. In genotypically resistant leaves treated with ethionine and polyoxin D there were fewer necrotic cells associated with stem rust colonies than in leaves treated with buffer. The spacial distribution of necrotic cells was consistent with the view that necrosis occurs only in cells newly invaded after the temperature was lowered to 19 °C.The observations do not support the concept that host-cell necrosis in the hypersensitive reaction conditioned by this gene results from the death of the fungus.

Effects of the Srl5 allele for resistance on development of the stem rust fungus and cellular responses in wheat

1986 ◽  
Vol 64 (3) ◽  
pp. 626-631 ◽  
Author(s):  
H. D. M. Gousseau ◽  
B. J. Deverall
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Cell Formation ◽  
Cellular Responses ◽  
Host Cells ◽  
Puccinia Graminis ◽  
Wheat Line ◽  
Cell Necrosis ◽  
Virulent Strains ◽  
Mother Cells

The development of avirulent and virulent strains of stem rust (Puccinia graminis Pers. f.sp. tritici Eriks. & Henn.) in a susceptible wheat line and two cultivars bearing the Sr15 allele for resistance was studied, mainly by fluorescence microscopy. Formation of appressoria, substomatal vesicles, infection hyphae, and the first haustorium was unaffected by resistance. The first effect of Sr15 expression was a slower rate of haustorial mother cell formation and was first seen 48 h after inoculation. Effects on hyphal branching and colony radii followed. Necrosis of host cells was first seen at 42 h, but inspection of individual infection sites showed that necrosis did not coincide with effects on haustorial mother cells. It is possible that deterioration of host cells leading to visible host cell necrosis may be related to effects on rust development. Sr15 expression gave a mesothetic reaction, first seen microscopically 60 h after inoculation. Differences between individual infection sites in this reaction may be related to the timing of the onset of necrosis.

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.

Histological studies on host-cell necrosis conditioned by the Sr6 gene for resistance in wheat to stem rust

1977 ◽  
Vol 55 (11) ◽  
pp. 1445-1452 ◽  
Author(s):  
D. J. Samborski ◽  
W. K. Kim ◽  
R. Rohringer ◽  
N. K. Howes ◽  
R. J. Baker
Keyword(s):  
Triticum Aestivum ◽  
Stem Rust ◽  
Fungal Growth ◽  
Triticum Aestivum L ◽  
Host Cells ◽  
Puccinia Graminis ◽  
Near Isogenic Lines ◽  
Cell Necrosis ◽  
Calcofluor White ◽  
Histological Studies

Seedlings of resistant (Sr6) and susceptible (sr6) near-isogenic lines of wheat (Triticum aestivum L.) were inoculated with a race of stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn.) that was avirulent on the line with Sr6 and they were kept at 19, 25, 26, and 27 °C. Fluorescence microscopy was used to detect autofluorescing necrotic host cells and rust colonies after these were stained with a fiuorochrome (Calcofluor White M2R New).In leaves containing the Sr6 gene, a smaller percentage of colonies grown at 25 °C had necrotic cells associated with them than those that were grown at 19 °C. The incidence of colony-associated necrosis in these leaves could be further reduced by increasing the temperature to 26 °C and 27 °C. Similarly, the number of necrotic host cells per colony decreased with an increase in temperature. Colonies in genotypically resistant leaves were usually smaller than those in genotypically susceptible leaves, but the differences in colony sizes between these two lines decreased at the higher temperatures.When infected plants containing the Sr6 gene were kept for varying times at 25 °C and then were transferred to 19 °C, there was significantly less fungal growth and more necrosis than in plants kept continuously at 25 °C. This necrosis occurred largely in those cells that were invaded after the transfer to 19 °C, when the Sr6 gene was activated.

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.

Haustoria-like branches in axenic cultures of Puccinia graminis f. sp. tritici

1969 ◽  
Vol 47 (11) ◽  
pp. 1816-1817 ◽  
Author(s):  
P. G. Williams
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Artificial Culture ◽  
Axenic Cultures

Hyphae of the wheat stem rust fungus form short, lateral projections under conditions of artificial culture that are unfavorable for saprophytic growth. It is suggested that the structures are homologous with the haustoria of intercellular rust mycelium.

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