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.

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.

The effect of the Sr6 gene for host resistance on histological events during the development of stem rust in near-isogenic wheat lines

1974 ◽  
Vol 52 (5) ◽  
pp. 1107-1115 ◽  
Author(s):  
R. A. Skipp ◽  
D. J. Samborski
Keyword(s):  
Host Cell ◽  
Host Resistance ◽  
Infection Type ◽  
Fungal Growth ◽  
Host Cells ◽  
Puccinia Graminis ◽  
Cell Necrosis ◽  
Resistant Line ◽  
Resistant Infection ◽  
Wheat Lines

Seedling leaves of resistant (Sr6) and susceptible (sr6) near-isogenic wheat lines inoculated with urediospores of Puccinia graminis f. sp. tritici race C 17 (56) became infected at similar rates. Host cells of the resistant line became necrotic after haustorial penetration (beginning about 20 h after inoculation), whereas necrosis was rarely seen in the susceptible line and colonies grew to form sporulating pustules. Some colonies in the resistant line appeared to have stopped growing by about 60 h after inoculation, while others grew slowly, the area of necrosis increasing as they expanded.Inoculated resistant-line plants became susceptible when incubated at 25 °C rather than 20 °C. Provided that the plants were kept at 25 °C for at least 1 day before inoculation, no host cell became necrotic. The necrotic response was resumed, and a more resistant infection type developed when infected seedlings were transferred from 25 °C to 20 °C. The converse occurred when resistant plants were grown and incubated at 20 °C, then transferred to 25 °C.Effects on fungal growth and the action of the Sr6 gene were considered to be closely associated with host cell necrosis. Temperature sensitivity appeared to be a property of the host plant.

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.

Alterations in 1,4-Benzoxazinone Levels Following Inoculation with Stem Rust in Wheat Leaves Carrying Various Alleles for Resistance and Their Possible Role as Phytoalexins in Moderately Resistant Leaves

1990 ◽  
Vol 45 (11-12) ◽  
pp. 1151-1155 ◽  
Author(s):  
Claudia Bücker ◽  
Hans J. Grambow
Keyword(s):  
Triticum Aestivum ◽  
Stem Rust ◽  
Triticum Aestivum L ◽  
Puccinia Graminis ◽  
Conversion Product ◽  
Near Isogenic Lines ◽  
Wheat Leaves ◽  
Infection Types ◽  
Moderately Resistant

The contents of 1,4-benzoxazinone derivatives in wheat plants infected with Puccinia graminis Pers. f. sp. tritici Ericss. & Henn, race 32, and in uninfected controls were examined in four near-isogenic lines of different infection types: Triticum aestivum L., cultivar Prelude Sr5 (highly resistant), Sr24, Sr26 (moderately resistant), and srx (susceptible). In all infection types the contents of DIMBOA -glc and HMBOA -glc decrease with time in the uninfected controls as well as in the infected plants. However, following inoculation, the synthesis of HDIBOA -glc is drastically increased in the moderately resistant cultivars. The results suggest that this fully methylated 1,4-benzoxazinone may function as a phytoalexin in this type of interaction. The benzoxazolinone MBOA which has been described as an in vitro conversion product of the benzoxazinones mentioned above is not detected in inoculated or uninoculated leaves.

A histological study of interactions between avirulent races of stem rust and wheat containing resistance genes Sr5, Sr6, Sr8, or Sr22

1979 ◽  
Vol 57 (4) ◽  
pp. 324-331 ◽  
Author(s):  
R. Rohringer ◽  
W. K. Kim ◽  
D. J. Samborski
Keyword(s):  
Resistance Genes ◽  
Stem Rust ◽  
Chinese Spring ◽  
Histological Study ◽  
Fungal Growth ◽  
Triticum Aestivum L ◽  
Epidermal Cells ◽  
Host Cells ◽  
Colony Development ◽  
Mesophyll Cells

Primary leaves of wheat (Triticum aestivum L.) with and without resistance genes Sr5, Sr6, Sr8, or Sr22 were inoculated with avirulent races of stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn.) and examined by fluorescence microscopy. In leaves containing the Sr5 gene for resistance, both epidermal and mesophyll cells fluoresced when interacting with the fungus, indicating incompatibility. In leaves containing the Sr6 gene, interacting epidermal cells did not fluoresce and incompatibility was expressed only in mesophyll cells.When the effect of the Sr5 gene was studied in leaves with different genetic backgrounds, it was found that most colonies developed only one or two haustorial mother cells in leaves containing this gene in Prelude, Marquis, or Reliance backgrounds, when examined up to 72 h after incubation. Conversely, in leaves with the Chinese Spring background, one-third of the colonies continued to grow and they produced macroscopically visible lesions. Our observations indicated that the Chinese Spring genotype partially altered the expression of the Sr5 gene in mesophyll but not in epidermal cells. In contrast, the Sr6 gene was more effective in the Chinese Spring background than in the Prelude background.Rust development in leaves with or without the Sr8 gene was the same up to 60 h after incubation, when incompatibility in resistant plants was first detected by the appearance of fluorescing host cells. By 72 h, mean colony size in resistant leaves was smaller than that in susceptible leaves, evidently because growth of runner hyphae was inhibited. Apparently, the P8 gene for avirulence was not expressed until colonies had reached considerable size. In leaves containing the Sr22 gene for resistance, the sequence of histological events was similar to that in leaves containing Sr8, but fluorescing host cells appeared later (72 h) and colony growth was inhibited only at 96 h after incubation. In both of these interactions, fluorescing host cells developed at the periphery of colonies when incompatibility was expressed. The host-parasite interaction in cells invaded before that time remained compatible even at later stages of colony development. In leaves containing the Sr5 or the Sr8 gene, but not in those with the Sr6 gene, the growth of some colonies was inhibited although they were not associated with fluorescing host cells. Evidently, host-cell necrosis was closely associated with reduced fungal growth in interactions involving Sr6, but not in interactions involving the resistance genes Sr5 and Sr8.

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.

Increased Lipoxygenase Activity is Involved in the Hypersensitive Response of Wheat Leaf Cells Infected with A virulent Rust Fungi or Treated with Fungal Elicitor

1986 ◽  
Vol 41 (5-6) ◽  
pp. 559-563 ◽  
Author(s):  
Carlos A. Ocampo ◽  
Bruno Moerschbacher ◽  
Hans J. Grambow
Keyword(s):  
Hypersensitive Response ◽  
Hypersensitive Reaction ◽  
Rust Fungi ◽  
Lipoxygenase Activity ◽  
Puccinia Graminis ◽  
Compatible Interaction ◽  
Wheat Leaf ◽  
Wheat Leaves ◽  
Germ Tubes ◽  
Wheat Rust

The hypersensitive reaction in incompatible wheat-rust interactions is characterized by an increase in lipoxygenase activity detectable as early as 28 h after penetration of the pathogen. In contrast, lipoxygenase activity in the compatible interaction did not increase until the onset of sporulation.Lipoxygenase activity also increased following treatment of wheat leaves with an elicitor fraction from germ tubes of Puccinia graminis tritici.

Ultrastructure of compatible and incompatible reactions of sunflower to Plasmopara halstedii

1979 ◽  
Vol 57 (4) ◽  
pp. 315-323 ◽  
Author(s):  
Glenn Wehtje ◽  
Larry J. Littlefield ◽  
David E. Zimmer
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Host Cell ◽  
Epidermal Cell ◽  
Cortical Cell ◽  
Hypersensitive Reaction ◽  
Host Cells ◽  
Plasmopara Halstedii ◽  
Host Cell Wall ◽  
Host Plasma Membrane

Penetration of sunflower, Heliantluis animus, root epidermal cells by zoospores of Plasmopara halstedii is preceded by formation of a papilla on the inner surface of the host cell wall that invaginates the host plasma membrane. Localized degradation and penetration of the host cell wall by the pathogen follow. The invading fungus forms an allantoid primary infection vesicle in the penetrated epidermal cell. The host plasma membrane invaginates around the infection vesicle but its continuity is difficult to follow. Upon exit from the epidermal cell the fungus may grow intercellularly, producing terminal haustorial branches which extend into adjacent host cells. The fungus may grow through one or two cortical cell is after growing from the epidermal cell before it becomes intercellular. Host plasma membrane is not penetrated by haustoria. Intercellular hyphae grow toward the apex of the plant and ramify the seedling tissue. Resistance in an immune cultivar is hypersensitive and is triggered upon contact of the host cell with the encysting zoospore before the host cell wall is penetrated. Degeneration of zoospore cytoplasm accompanies the hypersensitive reaction of the host. Zoospores were often parasitized by bacteria and did not germinate unless penicillin and streptomycin were added to the inoculum suspension.

The inheritance of stem rust resistance in Thatcher wheat

2000 ◽  
Vol 80 (1) ◽  
pp. 53-63 ◽  
Author(s):  
D. R. Knott
Keyword(s):  
Stem Rust ◽  
Rust Resistance ◽  
Triticum Aestivum L ◽  
Stem Rust Resistance ◽  
Puccinia Graminis ◽  
Single Seed Descent ◽  
Good Resistance ◽  
Canadian Prairies ◽  
Single Seed ◽  
Inheritance Of Rust Resistance

Thatcher was the predominant wheat (Triticum aestivum L.) cultivar on the Canadian prairies in the 1950s. Until race 15B (TMH) of stem rust (Puccinia graminis pers. f. sp. tritici Eriks. & Henn.) became widespread, Thatcher had good resistance to stem rust, but was susceptible to leaf rust (P. recondita f. sp. tritici Rob. ex Desm.). Although genes for stem rust resistance have been identified in Thatcher, the inheritance of its resistance has never been fully understood. The objective of this research was to attempt to elucidate the inheritance of the resistance of Thatcher and to determine why it had a reputation as a poor parent for rust resistance. Over a period of 40 yr, crosses and backcrosses to a susceptible genotype and two sets of single seed descent (SSD) lines were studied. The second set of SSD lines was tested with isolates of six races of stem rust to which Thatcher is resistant. The data showed that Thatcher is a very heterogenous cultivar with individual plants differing widely in the genes for stem rust resistance that they carry. The inheritance of rust resistance varied greatly from race to race and was often quite complex. Either complementary genes or a gene plus a suppressor appeared to condition resistance to one race. Most genes gave resistance to only one race. The presence of Sr5, which Thatcher is known to have obtained from Kanred, was confirmed. Most of its many additional genes probably came from Iumillo durum wheat. Key words: Stem rust, Thatcher wheat, single seed descent

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