Characteristics of adhesion pads formed during imbibition and germination of urediniospores of Uromyces viciae-fabae on host and synthetic surfaces

Clement, John A.; Porter, Robert P.; Butt, Tariq M.; Beckett, A.

doi:10.1017/s0953756297004188

Cited by 21 publications

(9 citation statements)

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“…However, the involvement of an extracellular matrix or adhesion pad has been observed in adhesion of the related common maize rust fungus Puccinia sorghi (5) and the bean rust fungus Uromyces viciae-fabae (6,8,14,23), suggesting that a similar mechanism may be responsible for adhesion in the present study.…”

Section: Discussionmentioning

confidence: 45%

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Novel Fungitoxicity Assays for Inhibition of Germination-Associated Adhesion of Botrytis cinerea and Puccinia recondita Spores

Slawecki

Ryan

Young

2002

Appl Environ Microbiol

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Botrytis cinerea and Puccinia recondita spores adhere strongly to polystyrene microtiter plates coincident with germination. We developed assays for inhibition of spore adhesion in 96-well microtiter plates by using sulforhodamine B staining to quantify the adherent spores. In both organisms, fungicides that inhibited germination strongly inhibited spore adhesion, with 50% effective concentrations (EC 50 s) comparable to those for inhibition of germination. In contrast, fungicides that acted after germination in B. cinerea inhibited spore adhesion to microtiter plates only at concentrations much higher than their EC 50 s for inhibition of mycelial growth. Similarly, in P. recondita the ergosterol biosynthesis inhibitors myclobutanil and fenbuconazole acted after germination and did not inhibit spore adhesion. The assays provide a rapid, high-throughput alternative to traditional spore germination assays and may be applicable to other fungi.Various methods have been used to measure the sensitivity of filamentous fungi to antifungal compounds. Measurement of the inhibition of spore germination is one such technique. Since spore germination occurs very rapidly for many fungi, this approach frequently allows a fungitoxic effect to be measured within a few hours rather than one or more days, as is typical for methods based on inhibition of mycelial growth. A major disadvantage of spore germination tests for measuring fungitoxicity is the need for labor-intensive microscopic evaluation to assess germination. This problem has essentially precluded the use of germination assays in large-scale fungicide screening operations designed to discover new antifungal compounds.Germination assays are also very useful for evaluating the mechanism of action of antifungal compounds. For many compounds, spore germination is the growth stage that is most sensitive to inhibition. For example, the strobilurin class of fungicides, which block electron transport at the cytochrome bc 1 complex of the mitochondrial electron transport chain, are extremely potent inhibitors of spore germination but much less active as inhibitors of mycelial growth (19). On the other hand, many fungicides have little or no effect on spore germination but strongly inhibit mycelial growth. Examples of fungicides that typically act after germination in filamentous fungi include antimicrotubule agents, e.g., carbendazim and N-phenylcarbamates, which inhibit nuclear division (22), and inhibitors of ergosterol biosynthesis (4,20). Consequently, comparison of the potency of a compound as an inhibitor of germination with its activity in a mycelial growth assay can provide preliminary information on its mode of action.Botrytis cinerea is the causal agent of grey mold disease on a variety of fruits, vegetables, and field crops (1). Puccinia recondita f. sp. tritici, the causal agent of wheat leaf rust, is one of the most economically important pathogens of wheat (24). Because it is an obligate pathogen, methods for measuring in vitro fungitoxicity based on inhibition of...

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Section: Discussionmentioning

confidence: 45%

“…The adhesion of spores and germlings is commonly associated with the production of an extracellular matrix (5,6,8,14,17,18,23). There are two distinct stages of adhesion for B. cinerea (9,10).…”

Section: Discussionmentioning

confidence: 99%

Novel Fungitoxicity Assays for Inhibition of Germination-Associated Adhesion of Botrytis cinerea and Puccinia recondita Spores

Slawecki

Ryan

Young

2002

Appl Environ Microbiol

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“…Studies of the rust fungus, Uromyces viciae-fabae, have also demonstrated that dry urediniospores will initially adhere to a hydrophobie surface, probably by hydrophobie interactions (Clement et al 1994). After hydration, the strength of attachme nt increases over the next 30 min, due either to the release of extracellular matrix material from the spore or to capillary forces arising from water accumulation between the spore and the substratum (Clement et al 1997). Even autoclaved spores display the initial increase in attachment, indicating that it is a passive process .…”

Section: A Fungal Spore Adhesiveness On the Plant Surfacementioning

confidence: 99%

“…Thereafter, the strength of attachment of living (but not dead) spores continues to increase, during which time extracellular matrix material is released from the spore wall and germ pore to form an adhesive pad between the pathogen cells and the underlying substratum ( Fig. 2B; Clement et al 1997). The extracellular matrix secreted by fungal spores can alter the properties of the leaf surface (Fig.…”

Section: A Fungal Spore Adhesiveness On the Plant Surfacementioning

confidence: 99%