Molecular recognition in the homing responses of zoosporic fungi, with special reference to Pythium and Phytophthora

Deacon, J.W.; Donaldson, S. P.

doi:10.1016/s0953-7562(09)81278-1

Cited by 134 publications

(88 citation statements)

References 117 publications

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“…Deacon and Donaldson [73] described zoospores as "homing agents" or "site-selection agents, " because their motility is linked to receptor functions for detecting environmental signals. They described the zoospore homing response as a sequence requiring two factors: a chemotactic stimulus and a suitable surface on which zoospores can orient [73].…”

Section: Spatial Complexity Of Soil Biocontrol Systemsmentioning

confidence: 99%

“…They described the zoospore homing response as a sequence requiring two factors: a chemotactic stimulus and a suitable surface on which zoospores can orient [73]. Further, they pointed out that zoospores can precisely locate root tips, wounds, or even individual root cells, so that understanding the homing response and factors that may modify it is central to understanding zoosporic fungi and for attempts to control them.…”

Section: Spatial Complexity Of Soil Biocontrol Systemsmentioning

confidence: 99%

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Ecological Complexity and the Success of Fungal Biological Control Agents

Knudsen

Dandurand

2014

Advances in Agriculture

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Fungal biological control agents against plant pathogens, especially those in soil, operate within physically, biologically, and spatially complex systems by means of a variety of trophic and nontrophic interspecific interactions. However, the biocontrol agents themselves are also subject to the same types of interactions, which may reduce or in some cases enhance their efficacy against target plant pathogens. Characterization of these ecologically complex systems is challenging, but a number of tools are available to help unravel this complexity. Several of these tools are described here, including the use of molecular biology to generate biocontrol agents with useful marker genes and then to quantify these agents in natural systems, epifluorescence and confocal laser scanning microscopy to observe their presence and activity in situ, and spatial statistics and computer simulation modeling to evaluate and predict these activities in heterogeneous soil habitats.

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Section: Spatial Complexity Of Soil Biocontrol Systemsmentioning

confidence: 99%

Section: Spatial Complexity Of Soil Biocontrol Systemsmentioning

confidence: 99%

Ecological Complexity and the Success of Fungal Biological Control Agents

Knudsen

Dandurand

2014

Advances in Agriculture

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“…The effects of kinase inhibitors on these pathways have not been previously reported, but the other compounds have been tested against a subset of the stages in Phytophthora or Pythium (8,10,11,27,37,38). The inhibitors were added to sporangia 5 min before …”

Section: Effects Of Inhibitors On Differentiationmentioning

confidence: 99%

“…Indirect germination takes about 1 h and involves the cleavage of sporangial cytoplasm into multiple zoospores. These emerge from the sporangial apex and swim, displaying several tactic behaviors (8,20), until encystment occurs in response to chemical or physical stimulation (13). Encystment occurs within seconds, involving the detachment of flagella and cell wall deposition (13).…”

mentioning

confidence: 99%

Novel Protein Kinase Induced during Sporangial Cleavage in the Oomycete Phytophthora infestans

Judelson

Roberts

2002

Eukaryot Cell

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A study of the effect of inhibitors on zoospore development in Phytophthora infestans demonstrated the involvement of protein kinases and calcium and led to the discovery of a gene induced during zoosporogenesis that encoded a protein resembling Ca ؉2 -and calmodulin-regulated serine/threonine protein kinases. The calcium channel blocker verapamil and the calmodulin antagonist trifluoroperazine inhibited zoosporogenesis and encystment. The protein kinase inhibitors K-252a and KN-93 inhibited zoospore release, encystment, and cyst germination, and K-252a reduced zoospore viability. In contrast, the inhibitors had minor or no effects on sporangia directly germinating in media. Spurred by these findings, a survey of putative protein kinase genes was performed to identify any that were up-regulated during zoosporogenesis. A kinase-encoding gene was identified for which mRNA accumulation was first detected soon after chilling sporangia in water, conditions that induce sporangial cytoplasm to cleave and release zoospores. The transcript persisted in motile zoospores and in germinated cysts but was not detected in other tissues, including hyphae, hyphae placed in water, or directly germinating sporangia. The structure of the predicted protein was novel, as its C-terminal region, which binds calmodulin in related proteins, was unusually short. Concentrations of actinomycin D previously used in experiments that suggested that de novo transcription was not needed for zoosporogenesis or encystment only partially inhibited transcription of the kinase gene, probably due to poor uptake into sporangia.Dispersal by means of spores is a common feature of the life cycle of many lower eukaryotes. This includes the oomycetes, which encompass many important plant pathogens, including Phytophthora, Pythium, and the downy mildews. Oomycetes lack taxonomic affinity with the so-called true fungi (i.e., ascomycetes and basidiomycetes), instead being related to diatoms and brown algae (2, 15). The asexual sporangia of oomycetes either germinate directly through a germ tube or indirectly by releasing biflagellate zoospores. Many species germinate through either pathway, while others produce only zoospores and some germinate only directly (12,22,26). For species displaying both modes of germination, zoospores are considered most important for dispersal and host infection.One species exhibiting this duality in germination behavior is Phytophthora infestans, which causes late blight of potato and tomato. Sporangia form on sporangiophores that emerge from infected plant tissue or from hyphae on artificial media. As with other oomycetes, the sporangia of P. infestans are multinucleate, nondesiccated, and metabolically active. Germination becomes possible once sporangia detached from sporangiophores encounter liquid. Indirect germination predominates in the absence of nutrients and at cool temperatures, typically below 12°C (30). In contrast, direct germination is favored by higher temperatures and nutrients. Indirect germination takes about 1 h...

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“…The zoospores swim through water in the soil and are chemotactically attracted to the exudates released by the roots of potential host plants (11,14). After the zoospores have adhered to the root surface, they encyst and produce a precisely oriented germ tube that grows into adjacent host plant tissue (3). The progression from zoospores to germlings is triggered by environmental signals, some of which are produced by the plant root.…”

mentioning

confidence: 99%

Phage-Displayed Peptides as Developmental Agonists for Phytophthora capsici Zoospores

Bishop-Hurley¹,

Mounter

Laskey³

et al. 2002

Appl Environ Microbiol

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As part of its pathogenic life cycle, Phytophthora capsici disperses to plants through a motile zoospore stage. Molecules on the zoospore surface are involved in reception of environmental signals that direct preinfection behavior. We developed a phage display protocol to identify peptides that bind to the surface molecules of P. capsici zoospores in vitro. The selected phage-displayed peptides contained an abundance of polar amino acids and proline but were otherwise not conserved. About half of the selected phage that were tested concomitantly induced zoospore encystment in the absence of other signaling agents. A display phage was shown to bind to the zoospore but not to the cyst form of P. capsici. Two free peptides corresponding to active phage were similarly able to induce encystment of zoospores, indicating that their ability to serve as signaling ligands did not depend on their exact molecular context. Isolation and subsequent expression of peptides that act on pathogens could allow the identification of receptor molecules on the zoospore surface, in addition to forming the basis for a novel plant disease resistance strategy.Phytophthora capsici is a soilborne pathogenic protist (phylum Oomycota) that infects aerial and subterranean structures of many solanaceous plants. Diseases caused by P. capsici are polycyclic in that multiple cycles of infection and inoculum production occur in a single growing season (20). The pathogen survives unfavorable conditions in soil by forming thickwalled oospores, while dissemination and infection are achieved through the production of motile biflagellate zoospores from oospores. The zoospores swim through water in the soil and are chemotactically attracted to the exudates released by the roots of potential host plants (11,14). After the zoospores have adhered to the root surface, they encyst and produce a precisely oriented germ tube that grows into adjacent host plant tissue (3). The progression from zoospores to germlings is triggered by environmental signals, some of which are produced by the plant root. Receptors on the surfaces of the zoospores, cysts, and germ tubes detect the environmental signals that trigger or orient each developmental event.Control of Phytophthora infection remains an ongoing agricultural problem and is most commonly accomplished by the application of biocides, such as methyl bromide or metalaxyl, to the soil. The ability of oospores to persist in soil for long periods obviates the use of crop rotation as an antipest strategy. Alternative, more environmentally benign methods of control will likely have to target host-specific stages of the infectious cycle, since the pathogen is so persistent.In the present study, we explore the possibility of using specific peptide ligands to interfere with the normal developmental progression of the pathogen. We reasoned that, since zoospores are chemotactic toward the plant surface and since the development of the pathogen involves interaction with the plant surface, surface receptor molecules on the zoosp...

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Molecular recognition in the homing responses of zoosporic fungi, with special reference to Pythium and Phytophthora

Cited by 134 publications

References 117 publications

Ecological Complexity and the Success of Fungal Biological Control Agents

Ecological Complexity and the Success of Fungal Biological Control Agents

Novel Protein Kinase Induced during Sporangial Cleavage in the Oomycete Phytophthora infestans

Phage-Displayed Peptides as Developmental Agonists for Phytophthora capsici Zoospores

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