Host-Pathogen Interactions

Cline, Kenneth; Albersheim, Peter

doi:10.1104/pp.68.1.207

Cited by 43 publications

(19 citation statements)

References 12 publications

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“…Our results have shown that soybean cells have several wall-bound enzymes with the necessary ,B-1,3-glucanase and ,B-glucosidase activities (8). The dominant f-1,3-glucanase in soybean walls has been purified and characterized.…”

mentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

“…The dominant f-1,3-glucanase in soybean walls has been purified and characterized. This enzyme, which we call ,Bglucosylase I, is also a ,B-glucosidase (8).…”

mentioning

confidence: 99%

“…The dominant f-1,3-glucanase in soybean walls has been purified and characterized. This enzyme, which we call ,Bglucosylase I, is also a ,B-glucosidase (8 It is difficult to obtain the low molecular weight culture filtrate elicitor in quantities sufficient for enzyme hydrolysis experiments.Fortunately, for the studies reported here, substantial quantities of elicitor-active oligosaccharides have recently been prepared from Pms mycelial walls by partial acid hydrolysis (19). These acid-prepared oligosaccharides were used for the enzyme-hydrolysis experiments described in this paper.…”

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confidence: 99%

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Host-Pathogen Interactions

Cline¹,

Albersheim²

1981

Plant Physiol.

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The ability of ,B-glucosylase I, a soybean cell wail f8-glucosyl hydrolase, to degrade elicitors of phytoalexin accumulation was studied. Extensive ,B-glucosylase I treatment of the glucan elicitor isolated from the mycelial walls of Phytophthora megasperma var. sojae results in hydrolysis of 77% of the glucosidic bonds of the elicitor and destruction of 94% of its activity. Soybean cell walls contain some additional factor, probably one or more additional enzymes, which can assist ,B-glucosylase I in hydrolyzing the glucan elicitor. This was demonstrated by the more rapid hydrolysis of the glucan elicitor by a mixture of soybean cell wai enzymes (containing .8-glucosylase I). In a single treatment, the mixture of cell wail enzymes hydrolyzed 91% of the glucosidic bonds and destroyed 85% of the activity of the elicitor. The enzymes from soybean cell wails will also hydrolyze elicitor-active oligoglucosides prepared from the mycelial walls of Phytophthora megasperma var. sojae. The active oligoglucosides are more susceptible than the glucan elicitor to hydrolysis by these enzymes. The mixture of cell wail enzymes or ,8-glucosylase I, by itself, hydrolyzes more than 96% of the glucosidic bonds and destroys more than 99% of the activity of the oligoglucoside elicitor. Two possible advantages for the existence of these enzymes in the walls of soybean cells are discussed.Pms,4 a fungal pathogen of soybeans, produces a f3-glucan which will stimulate soybeans and other higher plants to accumulate phytoalexins (2-4). Phytoalexin accumulation is thought to be a plant defense response to microbial attack (2).We are interested in knowing if soybeans possess enzymes capable of hydrolyzing the glucan which elicits this response. Our results have shown that soybean cells have several wall-bound enzymes with the necessary ,B-1,3-glucanase and ,B-glucosidase activities (8). The dominant f-1,3-glucanase in soybean walls has been purified and characterized. This enzyme, which we call ,Bglucosylase I, is also a ,B-glucosidase (8 It is difficult to obtain the low molecular weight culture filtrate elicitor in quantities sufficient for enzyme hydrolysis experiments.Fortunately, for the studies reported here, substantial quantities of elicitor-active oligosaccharides have recently been prepared from Pms mycelial walls by partial acid hydrolysis (19). These acid-prepared oligosaccharides were used for the enzyme-hydrolysis experiments described in this paper. MATERIALS AND METHODSChemicals. Bio-Gel P-2 was obtained from Bio-Rad. Sephadex Preparation of Pms Elicitors Purification of Pms Mycelial Walls. Race 1 of Pms was cultured as described (3). The Pms mycelial walls were purified by a modification of the procedure of Ayers et aL (4) as follows: mycelia, resulting from approximately 14 days of growth, were collected by suction filtration through nylon screen (37 ,um pore opening) which was supported on a Buchner funnel. The mycelial mat was washed on the funnel with distilled H20 until the liquid passing through the filter bec...

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mentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

“…The dominant f-1,3-glucanase in soybean walls has been purified and characterized. This enzyme, which we call ,Bglucosylase I, is also a ,B-glucosidase (8).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Host-Pathogen Interactions

Cline¹,

Albersheim²

1981

Plant Physiol.

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“…The following assays were performed spectrophotometrically: (a) phenylalanine ammonia-lyase, by monitoring the formation of cinnamic acid at 290 nm [2]; (b) chalcone isomerase, by monitoring the disappearance of 4,2',4-trihydroxychalcone absorbance at 400 nm in the presence of 50 mM KCN [19]; (c) peroxidase, by monitoring the H 2 0 2 -dependent oxidation of guaiacol at 420 nm [20] [27]. Assay of the following enzymes was performed using radiolabelled substrates: (a) caffeic acid 0-methyltransferase, where [OMe-14C]ferulic acid was formed from caffeic acid and S-adenosyl-~-[Me-'~C]methionine [28] Protein concentration was measured by the method of Bradford [30].…”

Section: Enzyme Assaysmentioning

confidence: 99%

Metabolic changes in elicitor-treated bean cells. Selectivity of enzyme induction in relation to phytoalexin accumulation

1985

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1. Treatment of cell suspension cultures of Phaseolus vulgaris C.V. Immuna with an elicitor preparation heatreleased from the cell walls of the phytopathogenic fungus Colletotrichum lindemuthianum resulted in rapid accumulation of the prenylated 5-hydroxyisoflavanone phytoalexin kievitone followed by later accumulation of the pterocarpan-derived phytoalexin phaseollin. Kievitone formation was preceded by rapid transient increases in the extractable activities of the enzymes L-phenylalanine ammonia-lyase and chalcone synthase.2. The extractable activites of 15 enzymes were measured in the cell cultures during the period of kievitone accumulation. The results suggest a highly selective induction of enzymes associated directly with the phytoalexin pathway. No induction of enzymes of pathways diverging from or providing Substrates for the phenylpropanoid + isoflavonoid pathway was observed. The increase in glutamate dehydrogenase activity in control cultures was prevented by elicitor application.3. A comparison of enzyme activities in control and Colletotrichum-infected bean hypocotyls provided further evidence of the selective induction of enzymes of phytoalexin synthesis, although peroxidase, glutamate dehydrogenase and glutamate synthase activities were higher in infected than in healthy hypocotyls.4. It is concluded that the major enzymic changes occurring in elicitor-treated bean cells are probably those directly associated with defence mechanisms such as the formation of isoflavonoid phytoalexins (this paper) or accumulation of phenolic compounds and hydroxyproline-protein in the cell walls [Bolwell, G. P. et al. (1985) Eur. J. Biochem. 148, 571 -5781.Previous studies have shown that the accumulation of isoflavonoid phytoalexins (host synthesised, antimicrobial compounds) in bean cell suspension cultures treated with elicitor from the cell walls of the phytopathogenic fungus Colletotrichum lindemuthianum is preceded by increased extractable activities and rates of synthesis of key biosynthetic enzymes of the phenylpropanoid pathway and flavonoid branch pathway leading to phytoalexins [l -31. Similar enzyme changes are associated with the phytoalexin response in soybean [4]. However, with the exceptions of the characterisation of a 3-9,dihydroxypterocarpan 6a-hydroxylase and the penultimate enzyme in the biosynthesis of the glyceollins in Correspondence to R. A. Dixon,

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Biological function of ‘pathogenesis-related’ proteins: four PR proteins of tobacco have 1,3-β-glucanase activity

et al. 1987

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Three of the ten acidic ‘pathogenesis‐related’ (PR) proteins known to accumulate in Nicotiana tabacum cv Samsun NN reacting hypersensitively to tobacco mosaic virus, namely −O, −N and −2, have been shown to have 1,3‐β‐glucanase (EC 3.2.1.39) activity. By using sera raised against each protein purified to homogeneity close serological relationships have been demonstrated between the three proteins. The same specific sera cross‐reacted with a basic protein which is also a 1,3‐β‐glucanase induced by virus infection and which can be considered as a new basic pathogenesis‐related protein of tobacco. Protein PR‐O and the basic 1,3‐β‐glucanase display about the same specific enzymatic activity, i.e. 50‐fold and 250‐fold higher than specific activities of proteins PR‐N and −2 respectively.

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Host-Pathogen Interactions

Cited by 43 publications

References 12 publications

Host-Pathogen Interactions

Host-Pathogen Interactions

Metabolic changes in elicitor-treated bean cells. Selectivity of enzyme induction in relation to phytoalexin accumulation

Biological function of ‘pathogenesis-related’ proteins: four PR proteins of tobacco have 1,3-β-glucanase activity

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