Effects of calcium on germination and further zoospore release from zoospore cysts of Phytophthora parasitica

Broembsen, S. L. von; Deacon, J.W.

doi:10.1016/s0953-7562(96)80085-2

Cited by 44 publications

(33 citation statements)

References 31 publications

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“…Phytophthora nicotianae van Breda de Haan isolate 1828 (DSMZ) was cultivated at 24°C on clarified tomato agar as described by von Broembsen and Deacon (1996). Zoospores were produced under aseptic conditions according to von Broembsen and Deacon (1996).…”

Section: Plant Growth and Characterizationmentioning

confidence: 99%

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RNA Interference-Mediated Repression of Cell Wall Invertase Impairs Defense in Source Leaves of Tobacco

et al. 2008

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The significance of cell wall invertase (cwINV) for plant defense was investigated by comparing wild-type tobacco (Nicotiana tabacum) Samsun NN (SNN) with plants with RNA interference (RNAi)-mediated repression of cwINV (SNNTcwINV). In source leaves of SNNTcwINV, the activity of cwINV was repressed by about 90%. Sucrose export and apoplastic carbohydrate levels were significantly reduced, while photosynthesis and dark respiration exhibited little or no change. Activities of sucrose synthase and phosphofructokinase were depressed moderately, while ADP-glucose pyrophosphorylase was diminished greatly. Yet, the content of cytosolic/vacuolar carbohydrates was not significantly lower, which correlated with the absence of phenotypic effects in SNNTcwINV under normal growing conditions. By contrast, defense-related processes in primary metabolism and hypersensitive cell death were impaired and delayed in correlation with repression of cwINV. The increase in cwINV observed in source leaves of the resistant wild type following infection with Phytophthora nicotianae was absent in SNNTcwINV. Also, defense-related callose deposition at cell-to-cell interfaces, the related decline in sugar export, and accumulation of apoplastic carbohydrates were reduced and delayed. Expression of pathogenesis-related proteins and increase in phenylalanine ammonialyase and glucose-6-phosphate dehydrogenase activities were alleviated. Formation of hydrogen peroxide and development of hypersensitive lesions were weak and heterogeneous, and the pathogen was able to sporulate. We conclude that in photosynthetically active leaves of the apoplastic phloem loader, tobacco cwINV plays an essential role for acquisition of carbohydrates during plant-pathogen interactions and that the availability of these carbohydrates supports the onset of the hypersensitive reaction and ensures successful defense.

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Section: Plant Growth and Characterizationmentioning

confidence: 99%

“…Zoospores were produced under aseptic conditions according to von Broembsen and Deacon (1996). Finally, the zoospores were stored in sterile tap water.…”

Section: Plant Growth and Characterizationmentioning

confidence: 99%

RNA Interference-Mediated Repression of Cell Wall Invertase Impairs Defense in Source Leaves of Tobacco

et al. 2008

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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%

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 strain and methods for zoospore production were as previously described (von Broembsen and Deacon, 1996) except that HPLC water (18.88 M⍀ · cm) (Purite Select Analyst 100 HP; Purite Ltd., Thame, UK) was used and the zoospores were released into a medium of low Ca 2ϩ concentration (Ͻ400-500 nM) consisting of 10 mM Tris-Cl buffer (ultra-high purity Tris, ICN Biomedicals, Thame, UK) in HPLC water, pH 7.20. Zoospore suspensions were diluted with buffer, as required, to a standard concentration of 5 ϫ 10 5 zoospores ml Ϫ1 .…”

Section: Zoospore Production and Encystmentmentioning

confidence: 99%

“…Then, if the encysting spores adhere to a surface they can germinate autonomously, but if they do not adhere in the first few minutes they require nutrients or a calcium supplement for germination (Donaldson and Deacon, 1992;von Broembsen and Deacon, 1996). The period of germination responsiveness to calcium is relatively short, after which a nontriggered cyst is destined to release a further zoospore (Persson and Sö derhäll, 1986).…”

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confidence: 99%

Transmembrane Ca2+Fluxes Associated with Zoospore Encystment and Cyst Germination by the PhytopathogenPhytophthora parasitica

Warburton

Deacon

1998

Fungal Genetics and Biology

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Effects of calcium on germination and further zoospore release from zoospore cysts of Phytophthora parasitica

Cited by 44 publications

References 31 publications

RNA Interference-Mediated Repression of Cell Wall Invertase Impairs Defense in Source Leaves of Tobacco

RNA Interference-Mediated Repression of Cell Wall Invertase Impairs Defense in Source Leaves of Tobacco

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

Transmembrane Ca2+Fluxes Associated with Zoospore Encystment and Cyst Germination by the PhytopathogenPhytophthora parasitica

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