scholarly journals Host resistance to fungi, chiefly in relation to obligate parasites

1948 ◽  
Vol 135 (879) ◽  
pp. 180-186 ◽  
Keyword(s):  
Culture Media ◽  
Rust Fungus ◽  
Wheat Variety ◽  
Structural Features ◽  
Biochemical Properties ◽  
Puccinia Graminis ◽  
Powdery Mildews ◽  
Obligate Parasites ◽  
Resistance To Invasion ◽  
Germ Tubes

The factors in the host conferring resistance to invasion by fungi which are obligate parasites are generally much more difficult to elucidate than where facultative parasites are involved, for the latter can be grown on culture media and their enzyme systems and other biochemical properties can be investigated in detail. At present, apart from the early stages after spore germination, a rust fungus can only be studied in relation to its host, and a clear analysis of the physiology of parasite and host respectively has not yet been achieved. Even in the rusts, however, structural features of the host occasionally confer some degree of resistance. In the wheat variety, Webster, profuse development of sclerenchyma in the stem checks mycelial growth of Puccinia graminis and confers a measure of resistance (Stakman, Levine & Griffee 1925), although other factors are also involved such as the tough character of the epidermis which impedes exposure of the pustules. Young barberry leaves are readily penetrated by the sporidial germ-tubes of P. graminis , whereas old leaves, provided with a thicker cuticle, are not infected. There is evidence, too, that the relative thickness of the cuticle is a factor in determining whether powdery mildews cause infection (Corner 1935). In connexion with attack by P. graminis on wheat it has been suggested (Hart 1929) that in some varieties tardy opening of the stomata in the morning confers a kind of functional resistance because the delicate germ-tubes of the spores on the surface are desiccated before penetration can be achieved. There is, however, some uncertainty about this interpretation.

scholarly journals Transfer of label from 3H-glucose in Digitaria eriantha leaves to the rust fungus Puccinia digitariae Pole Evans.

1985 ◽  
Vol 33 (8) ◽  
pp. 809-812 ◽  
Author(s):  
M E Rey ◽  
H M Garnett
Keyword(s):  
Primary Infection ◽  
Secondary Infection ◽  
Rust Fungus ◽  
Infection Process ◽  
Bremia Lactucae ◽  
Infection Structures ◽  
Obligate Parasites ◽  
Digitaria Eriantha ◽  
Germ Tubes

Digitaria eriantha pentzii was fed 3H-glucose prior to inoculation with uredospores of Puccinia digitariae Pole Evans. Twenty-one hours after inoculation, uptake of label from 3H-glucose by the primary infection structures of P. digitariae was demonstrated employing autoradiography. These results indicate that an exchange of nutrients between host and pathogen occurs very early on in the infection process, during the formation of the primary infection structures. Despite contrary reports that obligate parasites receive no nutrition before establishment of haustoria, this study supports the work of Andrews (Can J Bot 53:1103, 1975), who demonstrated uptake of 3H-glucose label from lettuce cotyledons into the primary and secondary infection vesicles, appressoria, and germ tubes of Bremia lactucae.

scholarly journals I. Mahonia aquifolia as a nurse of the wheat mildew ( Puccinia graminis )

1883 ◽  
Vol 36 (228-231) ◽  
pp. 1-3
Keyword(s):  
Life Cycle ◽  
Puccinia Graminis ◽  
Knowing That ◽  
The Common ◽  
Germ Tubes

It has always been difficult to account for the widely-spread nature of outbreaks of wheat mildew in districts in which the common barberry is either entirely absent or very uncommon. In the year 1874 the Rev. James Stevenson found at Glamis, in Forfarshire, an Æcidium upon Mahonia aquifolia , which the Rev. M. J. Berkelev pronounced to be Æcidium berberidis . In the following year Dr. Paul Magnus found the same fungus at Lichterfelde, near Berlin, but since that time it does not seem to have been noticed by any one. On the 31st of May, 1883, Mr. William C. Little, of Stagsholt, March, gave me a freshly gathered specimen of Mahonia aquifolia , upon the berries of which the Æcidium was abundant. Knowing that upon the barberry no less than three different AEcidia occur, I determined to prove by direct experimental culture whether this one was the Æeidium berberidis of Persoon (the æcidiospore of Puccinia graminis ). At 10 p. m. on the evening of the 31st May I placed some of the spores upon the cuticle of some wheat-plants which had been cultivated under a bell-glass. In eleven days the uredo of Puccinia graminis made its appearance upon these plants. The details of this, as well as of two other experiments, are appended. On the 13th June I placed some of the secidiospores upon a piece of wheat cuticle; in twelve hours they had germinated, and a little later the germ-tubes were seen entering the stomata, in the same manner as those of Æcidium berberidis do (see figure). It is then clear that the Æcidium upon Mahonia aquifolia is identical with the Æcidium berberidis (Pers.), and is a part of the life-cycle of Puccinia graminis , and is unconnected with the Æcidium magellanicum (Berk.), and the Æcidium of Puccinia berberidis (Mont.). The Mahonia in question is widely cultivated in gardens throughout England and is a favourite evergreen in shrubberies. It is also extensively planted in woods as a covert for game.

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.

scholarly journals Catalase and Ascorbate Peroxidase in Euglenozoan Protists

Pathogens ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 317 ◽  
Author(s):  
Ingrid Škodová-Sveráková ◽  
Kristína Záhonová ◽  
Barbora Bučková ◽  
Zoltán Füssy ◽  
Vyacheslav Yurchenko ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Ascorbate Peroxidase ◽  
Biochemical Properties ◽  
Heterotrophic Flagellates ◽  
Oxygen Species ◽  
Detoxifying Enzymes ◽  
Free Living ◽  
Present Evidence ◽  
Obligate Parasites ◽  
Membrane Bound

In this work, we studied the biochemical properties and evolutionary histories of catalase (CAT) and ascorbate peroxidase (APX), two central enzymes of reactive oxygen species detoxification, across the highly diverse clade Eugenozoa. This clade encompasses free-living phototrophic and heterotrophic flagellates, as well as obligate parasites of insects, vertebrates, and plants. We present evidence of several independent acquisitions of CAT by horizontal gene transfers and evolutionary novelties associated with the APX presence. We posit that Euglenozoa recruit these detoxifying enzymes for specific molecular tasks, such as photosynthesis in euglenids and membrane-bound peroxidase activity in kinetoplastids and some diplonemids.

STUDIES ON THE NATURE OF RUST RESISTANCE IN WHEAT: VI. EFFECT OF HYDROGEN ION CONCENTRATION, PHENOLIC COMPOUNDS, AND HOST EXTRACTS ON THE GERMINATION OF UREDINIOSPORES OF PUCCINIA GRAMINIS TRITICI, FORM 21

1934 ◽  
Vol 11 (6) ◽  
pp. 667-686 ◽  
Author(s):  
J. Ansel Anderson
Keyword(s):  
Phenolic Compounds ◽  
Rust Resistance ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Puccinia Graminis ◽  
Inhibitory Effects ◽  
Hydrogen Ion Concentration ◽  
Puccinia Graminis Tritici ◽  
The Press ◽  
Germ Tubes

Urediniospores of Puccinia graminis tritici, form 21, were sown on buffer solutions covering the range from pH 3 to pH 8. Maximum germination was obtained between pH 5.8 and 6.5, with indications that if the point of maximum germination could be determined with precision it would be found to lie in the neighborhood of pH 6.2.The effect of buffered and unbuffered solutions of pure phenolic compounds on the germination of urediniospores was studied. Greater inhibition was obtained with unbuffered solutions owing to the additional effect of hydrogen ion concentration. In buffered solutions, at pH 6.0, germination was prevented by 45 p.p.m. of hydroquinone, 125 of o-cresol, 180 of anisic acid, 250 of benzoic acid, 340 of catechol, 400 of guaiacol and 600 of phenol. A number of other compounds were also studied. The inhibitory effects of compounds, of which the bactericidal effects are known, are fairly closely related to their bactericidal efficiency.Investigations were made of the inhibitory effects on spore germination and the growth of germ tubes, of aqueous dilutions of 15, 10, 5 and 2.5% of the press-juice of Vernal, Khapli, Marquis and Little Club wheats. Statistical treatment of the data accumulated in ten series of determinations, in which a total of 160,000 spores was counted, showed that significant differences occurred between varieties and that variations in the total solid content and hydrogen ion concentration of the press-juice had no consistent effect upon the results. Although the results were not entirely clear-cut, it is concluded that the varieties fall in the following order with respect to increasing inhibitory effect of their extracts: Vernal, Marquis, Khapli and Little Club. Since Vernal and Khapli are resistant to form 21 whereas Marquis and Little Club are susceptible, the results fail to show any relationship between the effects of host extracts on the germination of urediniospores, or on the growth of germ tubes, and the rust resistance of the variety.

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.

scholarly journals STRUCTURAL FEATURES AND BIOCHEMICAL PROPERTIES OF TNF-ALPHA CONVERTASE

Shock ◽  
1997 ◽  
Vol 7 (Supplement) ◽  
pp. 76-77
Author(s):  
M. Moss ◽  
C. Jin ◽  
D. Becherer ◽  
M. Bickett ◽  
W. Burkhart ◽  
...  
Keyword(s):  
Structural Features ◽  
Biochemical Properties ◽  
Tnf Alpha

Rod-shaped and spherical viruslike particles in cowpea rust fungus

1978 ◽  
Vol 56 (8) ◽  
pp. 963-975 ◽  
Author(s):  
John G. McDonald ◽  
Michèle C. Heath
Keyword(s):  
Phosphotungstic Acid ◽  
Rust Fungus ◽  
Ammonium Molybdate ◽  
Size Distributions ◽  
Wide Diameter ◽  
Thin Sectioning ◽  
Rigid Rod ◽  
Viruslike Particles ◽  
The Stability ◽  
Germ Tubes

Three types of rod-shaped viruslike particles (VLPs) (a short rigid rod (RR), 260 × 12 nm. a long narrow-diameter flexuous rod (NFR), 660 × 10 nm, and a long wide-diameter flexuous rod (WFR), 740 × 16 nm) and a spherical VLP (35 nm in diameter) were found in extracts of uredospores, germ tubes, and pustules of cowpea rust, negatively stained with ammonium molybdate. Both the size distributions and the stability of these VLPs was affected by the choice of stain since when phosphotungstic acid was used, two additional length classes of the RR (150 nm and 90 nm) were noted, and this stain tended to disassemble the WFR by unwinding the helix of this particle. The WFR also disassembled at pHs 4and5 in 10 mM acetate but only at pH 4 in the presence of 0.2 M NaCl. Examination of cowpea rust by thin sectioning revealed the presence of four types of VLPs. Morphologies of these particle types were consistent with the data obtained by negative staining.

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