Effects of Host-Selective SV-Toxin from<i>Stemphylium vesicarium</i>, the Cause of Brown Spot of European Pear Plants, on Ultrastructure of Leaf Cells

Singh, Pooran; Park, P.; Bugiani, R.; Cavanni, P.; Nakajima, Hiromitsu; Kodama, Motoichiro; Otani, Hiroshi; Kohmoto, Keisuke

doi:10.1046/j.1439-0434.2000.00474.x

Cited by 25 publications

(17 citation statements)

References 11 publications

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“…The mode of action of SS-toxin, therefore, appeared to be compatible with the hypothesis that plasma-membrane and cell-wall disorders, caused directly or indirectly by SS-toxin, were key factors in early pathogenesis on garlic leaves, leading to pathogen access to host cells, and that SS-toxin could disrupt the structure of cellular organelles (14,19). One well-documented case of phytotoxininduced membrane damage is SV-toxin of S. vesicarium; however, SV-toxin only caused plasma membrane modifications in susceptible pear tissues (20) and not in resistant ones. In this study, SS-toxin also induced some changes in a resistant garlic cultivar but at a much slower rate, and with higher threshold concentrations.…”

Section: Discussionsupporting

confidence: 83%

“…Treated leaves were then incubated at 25°C for 2, 6, 12, or 24 h in a moist chamber. Following previously described procedures (20), tissues of toxin or control treated sites were cut into small pieces and prefixed with 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.2) for 6 h at 4°C. After rinsing with the phosphate buffer several times, leaf tissues were postfixed with 1.5% osmium tetroxide in the phosphate buffer for 2 h at 4°C.…”

Section: Methodsmentioning

confidence: 99%

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Isolation, Purification, and Biological Activity of a Phytotoxin Produced by Stemphylium solani

Zheng

Huang

et al. 2010

Plant Disease

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Stemphylium solani, the causal agent of leaf blight of garlic (Allium sativum), produced phytotoxic metabolites in culture. A non-host-specific phytotoxin from culture filtrate of S. solani isolate DY-5, named SS-toxin, was extracted by ethyl acetate, isolated by bioassay-guided thin layer chromatography on silica gel, and purified by preparative liquid chromatography. SS-toxin produced necrotic lesions on detached garlic leaves, similar to that caused by S. solani. When wounded leaves were each treated with a 10-μl droplet of toxin, Changbanpo, a garlic cultivar susceptible to leaf blight, showed necrotic lesions at 11 μg/ml toxin, while a resistant cultivar, Qingganruanye, showed symptoms at 44 μg/ml. The effective doses causing 50% inhibition (EC50 values) of root growth and shoot elongation of the susceptible cultivar were 64.9 and 178.5 μg/ml, respectively. The SS-toxin significantly inhibited mitotic activity of root tip cells of the susceptible cultivar from 22 μg/ml and higher causing an abnormally high frequency of cells in interphase. Concentrations over 50 μg/ml of SS-toxin were found to be significantly toxic to total chlorophyll, both chlorophyll a and b, of the susceptible cultivar. The plasma membrane–cell wall interface, nuclear membranes, mitochondria, and chloroplasts were affected by SS-toxin in susceptible leaf cells. This is the first report of the purification and testing of a phytotoxin produced by S. solani.

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Section: Discussionsupporting

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Isolation, Purification, and Biological Activity of a Phytotoxin Produced by Stemphylium solani

Zheng

Huang

et al. 2010

Plant Disease

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“…It can be argued that the fungus did not lose its ability in producing phytotoxins (Singh et al, 1999(Singh et al, , 2000 when it developed as a saprophyte, as all the fungal strains re-isolated from lawn leaves and inoculated on leaves of the susceptible pear 'Abate Fe´tel' produced typical disease symptoms.…”

Section: Discussionmentioning

confidence: 99%

Growth and sporulation of Stemphylium vesicarium, the causal agent of brown spot of pear, on herb plants of orchard lawns

et al. 2005

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The inoculum sources of ascospores of Pleospora allii and of conidia of its anamorph Stemphylium vesicarium were investigated in relation to the brown spot disease epidemiology on pear. Dead and living leaves of three pear varieties (Abate Fe´tel, Conference and William), seven grasses (Poa pratensis, Festuca rubra, Festuca ovina, Lolium perenne, Digitaria sanguinalis and Setaria glauca) and Trifolium repens, which are used in pear orchard lawns, were inoculated with conidia of Stemphylium vesicarium virulent on pear and incubated under controlled-environment. Stemphylium vesicarium was always re-isolated from dead leaves of the considered plants, but not from symptomless green or yellowish living leaves. The fungus was occasionally re-isolated from leaf segments showing unspecific necrosis. Inoculation of pear leaves with isolates from grasses demonstrated that the fungus did not lose pathogenicity. Pseudothecia, ascospores and conidia were produced on all the dead inoculated leaves; differences between specimens were found for phenology of pseudothecia, their density and size, and for the number of conidia produced. Pseudothecia were produced faster in the lawn species than in pear leaves, and their density was higher, especially for S. glauca, L. perenne and P. pratensis. Ascospore maturation and ejection was more concentrated for the pseudothecia developed on pear leaves than for those on F. ovina and S. glauca. All the lawn species produced more conidia than pear leaves.

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“…The slightly damaged subtype is typical of susceptible genotypes treated with AF-toxin (Park et al 1981a(Park et al , 1992aPark and Unno 1999), AM-toxin (Park et al , 1981bShimomura et al 1992Shimomura et al , 1993, and alternaric acid (Langsdorf et al 1991). The severely damaged subtype was found in host tissues treated with AK-toxin (Park 1977a(Park , b, c, d, e, f, 1991(Park , 1998Park et al 1976Park et al , 1981aPark et al , b, 1989Park et al , 1992bPark et al , 1994Shimizu et al 2005a;Shinogi et al 2001;Suzuki et al 2002), AFtoxins (Park et al 1981(Park et al , 1992aPark and Unno 1999), SVtoxin (Singh et al 2000) and ACT-toxin (Itoh et al 1993). AK-toxin I is the HST produced from A. alternata Japanese pear pathotype and is the causal fungus of black spot disease of pear plants (Tanaka 1933); AF-toxin I is from A. alternata strawberry pathotype (the causal fungus of black spot disease of strawberry) (Maekawa et al 1984); AM-toxin I is from A. alternata apple pathotype (the causal fungus of Alternaria blotch in apple plants) (Sawamura 1965); and SV-toxin is from S. vesicarium (the causal fungus of brown spot disease in European pear plants) (Signh et al 2000).…”

Section: Mode Of Action Of Alternaria and Stemphylium Host-specific Tmentioning

confidence: 99%

Ultrastructural analysis of responses of host and fungal cells during plant infection

Park

Ikeda

2007

J Gen Plant Pathol

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Cellular responses in fungi and in susceptible or resistant hosts during fungus-plant interactions have been studied ultrastructurally to examine their role in pathogenicity. Pathogenicity is determined in some saprophytic fungi by various factors: the production of disease determinants such as the production of host-specific toxins (HSTs) or the extracellular matrix (ECM) by fungal infection structures and H 2 O 2 generation from penetration pegs. Three different target sites for HSTs have been identified in host cells in many ultrastructural studies: plasma membranes, chloroplasts, and mitochondria. The mode of action of HSTs is characterized by the partial destruction of the target structures only in susceptible genotypes of host plants, with the result that the fungus can colonize the host. The infection structures of most fungal pathogen secrete ECM on plant surfaces during fungal differentiation, while the penetration pegs of some pathogens produce reactive oxygen species (ROS) in the cell walls and plasma membranes. The pathological roles of ECM and H 2 O 2 generation are discussed here in light of ultrastructural evidence. Host and fungal characteristics in the incompatible interactions include the rapid formation of lignin in host epidermal cell walls, failure of penetration pegs to invade lignin-fortified pectin layers, the inhibition of subcuticular hyphal proliferation and the collapse of hyphae that have degraded cell walls within pectin layers of the host. Apoptosis-like host resistant mechanism is also discussed.

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Effects of Host-Selective SV-Toxin fromStemphylium vesicarium, the Cause of Brown Spot of European Pear Plants, on Ultrastructure of Leaf Cells

Cited by 25 publications

References 11 publications

Isolation, Purification, and Biological Activity of a Phytotoxin Produced by Stemphylium solani

Isolation, Purification, and Biological Activity of a Phytotoxin Produced by Stemphylium solani

Growth and sporulation of Stemphylium vesicarium, the causal agent of brown spot of pear, on herb plants of orchard lawns

Ultrastructural analysis of responses of host and fungal cells during plant infection

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