Host-pathogen interactions in plants. Plants, when exposed to oligosaccharides of fungal origin, defend themselves by accumulating antibiotics.

Albersheim, Peter; Valent, Barbara

doi:10.1083/jcb.78.3.627

Cited by 256 publications

(99 citation statements)

References 41 publications

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“…The study of the active portion of the molecule indicates that altering the sugar moiety by weak alkali treatment leads to a decreased activity. It is likely that, as in the case of other elicitors (2,18), this activity resides in the sugar portion. Our data also indicate that elicitors contain phosphate residues and thus resemble the phosphoglycopeptide elicitor of phytoalexins isolated from Fulvia fulva (8).…”

Section: Discussionmentioning

confidence: 99%

“…microorganism interactions, but also the concept of elicitor activity in plants. It was notably found that chemical wounding was not necessary for the production of ethylene and that fungal elicitors have other activities than their well known effects on phytoalexin synthesis in plants (2,14). The present work which is concerned with the isolation, composition, and activity of these elicitors supports and extends these views.…”

Section: Discussionmentioning

confidence: 99%

“…In infected melon seedlings, for instance, ethylene is enhanced 30 h after inoculation; that is about 2 d before the appearance of symptoms (26,32). At that time, neither the main hydrolytic activities usually displayed by pathogens (2,10), nor the pathogen itself (30) are quantitatively detectable; so far no toxin release could be detected either. In fact, electron microscopy studies have shown that, until 3 d after inoculation, the fungus is surrounded by the host plasmalemma and restricted to the cell wall-plasmalemma interface (7).…”

Section: Biological Materialsmentioning

confidence: 99%

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Cell Surfaces in Plant-Microorganism Interactions

Toppan¹,

Esquerré-Tugayé²

1984

Plant Physiol.

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The production of ethylene by melon (Cucumis melo cv Cantaloup charentais) tissues is stimulated during incubation in the presence of fungal glycopeptides extracted from Colletotrichum lagenarium, a pathogen of melon. These glycopeptides, called elicitors of ethylene, are found in the mycelium, the cell wall, and the culture filtrate. Elicitation of ethylene is a relatively early phenomenon and lasts for several hours. Upon purification of the crude elicitor extract by gel filtration and ion exchange chromatography, three elicitors were isolated. The three elicitors contained amino acid, sugar, and phosphate residues, and they have a decreased activity after partial chemical degradation of their sugar moiety.Elicitation of ethylene is not funpl species specific. Elicitors of phytoalexins, obtained from three Phytophtora species, enhanced ethylene biosynthesis in melon tissues.initially by isolating from the fungal cell surface those molecules which elicit the synthesis of ethylene in plants (13,14). We describe in this paper the purification, composition, and activity of these molecules. MATERIALS AND METHODS BIOLOGICAL MATERIALSPlants. Melon (Cucumis melo cv Cantaloup charentais), soybean (Glycine max cv Harosoy 63), and tobacco (Nicotiana tabacum cv Paraguay) seedlings were cultivated in a growth chamber as already described for melons (10).Fungi. Colletotrichum lagenarium was obtained by liquid culture on a glucose-ammonium nitrate synthetic medium (10); 12-d-old culture was routinely used. A liquid culture of Phytophtora parasitica was obtained as indicated for Phytophtora megasperma (5).In previous studies, ethylene was reported to play a role in the accumulation of HRGP2 in the cell wall of diseased plants, and this accumulation was shown to be associated with the plant's defense mechanism (11,12,32). Knowledge of host-pathogen interactions which lead to the increased production of ethylene such as in the melon-Colletotrichum lagenarium system (26,32) is of prime importance in understanding the role ofthis hormone in cell wall modifications.It was thought for a long time that the large amount ofethylene evolved by infected plants is a wound-stress response to pathogen attack (1,3,29). However, this assumption is questionable in instances where the rise in ethylene production is an early event which happens soon after inoculation (21,25). In infected melon seedlings, for instance, ethylene is enhanced 30 h after inoculation; that is about 2 d before the appearance of symptoms (26,32). At that time, neither the main hydrolytic activities usually displayed by pathogens (2, 10), nor the pathogen itself (30) are quantitatively detectable; so far no toxin release could be detected either. In fact, electron microscopy studies have shown that, until 3 d after inoculation, the fungus is surrounded by the host plasmalemma and restricted to the cell wall-plasmalemma interface (7). Hence a hypothesis was developed which holds that, during the first 30 h after inoculation, ethylene might be increased, at least ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Biological Materialsmentioning

confidence: 99%

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Cell Surfaces in Plant-Microorganism Interactions

Toppan¹,

Esquerré-Tugayé²

1984

Plant Physiol.

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“…Phytoalexin production can be induced generally by cell wall extracts from compatible or incompatible fungi, and also by other compounds [5]. Recently we have observed that elicitor preparations from Alteunaria carthami Chowdhury (Ac elicitor), as well as elicitor preparations from P. megaspmnu f.sp.…”

mentioning

confidence: 99%

Differential Response of Cultured Parsley Cells to Elicitors from Two Non-pathogenic Strains of Fungi. 1. Identification of Induced Products as Coumarin Derivatives

1983

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Dark‐grown cell suspension cultures of parsley, Petroselinum hortense, produce furanocoumarins after treatment with elicitor preparations of either Phytophthora megasperma f.sp. glycinea (Pmg elicitor) or Alternaria carthami Chowdhury (Ac elicitor). The linear furanocoumarins, psoralen and xanthotoxin, and the benzodipyrandione, graveolone, are the major products synthesized in response to Pmg elicitor, besides small amounts of the furanocomarin bergapten. Treatment with Ac elicitor induces predominantly the formation of bergapten and the furanocoumarin isopimpinellin, as well as small amounts of graveolone. While Pmg elicitor leads to cell death within a few days, cell mass increased for at least 6 days after treatment with Ac elicitor. Brefeldin A, a phytotoxin produced by A. carthami, inhibits growth of parsley cell suspension cultures considerably at a concentration of 0.01 mM and growth of the cells ceased at a concentration of 0.1 mM toxin. Concomitantly, furanocoumarin biosynthesis was suppressed in our system by a concentration of brefeldin A within 0.01–0.1 mM.

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“…Phytoalexins also accumulate in plants in response to substances of pathogen origin termed elicitors, and these have been implicated in the induction of phytoalexin production in infected plants (1,11 …”

Section: Introductionmentioning

confidence: 99%

Release of a Soluble Phytoalexin Elicitor from Mycelial Walls of Phytophthora megasperma var. sojae by Soybean Tissues

Yoshikawa

Matama²,

Masago³

1981

Plant Physiol.

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A soluble elicitor of glyceollin accumulation was released from insoluble mycelial walls of Phytophthora megasperma var. sojae after incubation with soybean cotyledon tissue for as little as 2 minutes. Various enzymic and chemical treatments of the released elicitor indicated that the activity resided in a carbohydrate moiety, and gel filtration disclosed the presence of at least two active molecular species. Cell-free extracts from soybean cotyledons or hypocotyls also released soluble elicitors from fungal cell walls that were similar to those released by living cotyledon tissue. These results may suggest that contact of fungal pathogens with host tissues is required to release fungal wall elicitors which then initiate phytoalexin accumulation in the plant.Phytoalexins are low molecular weight antibiotic compounds that are inducibly formed in higher plants after infection by microorganisms and which confer natural disease resistance (4,11,12). Phytoalexins also accumulate in plants in response to substances of pathogen origin termed elicitors, and these have been implicated in the induction of phytoalexin production in infected plants (1,11 MATERIALS AND METHODSIsolation of Mycelial Wails. Race 1 of P. megasperma var. sojae was grown in an asparagine-glucose medium (9) supplemented with autoclaved soybean hypocotyl extract (16) at 25 C for 7 days. Mycelia were collected by suction filtration and washed with deionized H20. Mycelial walls were isolated by the method previously described (14) with slight modification to avoid use of organic solvents which may alter native wall structures or molecules. About 5 g batches of mycelia were finely pulverized in a mortar under liquid N2, and subsequent steps were performed at 0 C. The resulting powder was suspended in 20 ml of 20 mm Tris-HCI (pH 7.2) and briefly sonicated (I min, 5 times) to disperse small particles present inside mycelial fragments into the buffer medium. The suspension was centrifuged at lOOg for 5 min. The pellet was resuspended and washed by centrifugation with the same buffer three times. The wall suspension was again sonicated as described above, and the walls were washed with deionized H20 by centrifugation 7 times. The washed walls were lyophilized and before use, finely suspended in deionized H20 with a Waring Blendor. The isolated wall preparations appeared to be free from cytoplasmic contaminants under the microscope (Fig. 1), and the supernatant fraction of the wall suspension did not contain elicitor activity when assayed as described below.Release of Soluble Elicitor from Mycelial Wails by Soybean Cotyledons and Cell-free Extracts. The soybean cultivar Harosoy 63 was grown as described previously (15). Cotyledons from 8-day-old seedlings were wounded by cutting away the lower surface (about 1-mm thick). A 50-,Al aliquot of aqueous mycelial wall suspension (500 ,ug/ml) was placed onto the wounded areas of 30 cotyledons, and these were incubated on moist filter papers in Petri dishes at 25 C for the indicated time periods. At the en...

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Host-pathogen interactions in plants. Plants, when exposed to oligosaccharides of fungal origin, defend themselves by accumulating antibiotics.

Cited by 256 publications

References 41 publications

Cell Surfaces in Plant-Microorganism Interactions

Cell Surfaces in Plant-Microorganism Interactions

Differential Response of Cultured Parsley Cells to Elicitors from Two Non-pathogenic Strains of Fungi. 1. Identification of Induced Products as Coumarin Derivatives

Release of a Soluble Phytoalexin Elicitor from Mycelial Walls of Phytophthora megasperma var. sojae by Soybean Tissues

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