Biochemical Mechanisms of Disease Resistance

Bell, Alois A.

doi:10.1146/annurev.pp.32.060181.000321

Cited by 450 publications

(218 citation statements)

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“…Poly-L-lysine (1 1,000) 7 17 Poly-L-lysine (4,000) CHITOSAN AND Ca2l IN CALLOSE SYNTHESIS polymer became degraded to molecules which have a better access through the cell wall to the membrane. The importance, however, ofa relatively high mol wt ofthe polycations employed is evident from the results with poly-L-lysine (Table I) On addition of EGTA at a final concentration of 0.5 mm, the signal from the Ca2" electrode was below the detection limit which is at about 1 uLM.…”

Section: Resultsmentioning

confidence: 99%

“…3B, 4,5) and leakage of cell constituents appears to be an additional prerequisite. It can be induced by various agents such as chitosan, poly-L-lysine (Table I) and Polymyxin B (Table II), all of which seem to be at least partly nonspecific as they allow for the release of various substances from the cell, following their gradients of concentration (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…plasmodesmata, sieve pores), presumably to isolate the injured area (10). The localized deposition and speed of callose formation may be important in the first line of defense against pathogens as callose is also a major component of papillae or wall appositions which are formed at sites of attempted penetration by invading fungal hyphae (1,4). Callose is similarly found around lesions in certain virus-infected plants where it may help to prevent spreading of the virus (4,20).…”

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Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca²⁺-Dependent Process

Köhle¹,

Jeblick²,

Poten³

et al. 1985

Plant Physiol.

342

143

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A new method for the rapid and quantitative fluorometric determination of callose is described. In suspension-cultured cells of Glycine max, synthesis of callose starts within 20 minutes of treatment with chitosan and parallels over hours the accumulation of 1,3-linked glucose in the wall. Poly-L-lysine also elicits callose synthesis. The effect of chitosan is enhanced by Polymyxin B at low concentrations; this antibiotic alone at higher concentrations can also induce callose synthesis. Callose synthesis is immediately stopped when external Ca2l is bound by ethylene glycolbis-(2-aminoethyl ether)-N,N'-tetraacetate or cation exchange beads, and partly recovers upon restoration of 15 micromolar Ca21.Callose synthesis is observed only when membrane perturbation causing electrolyte leakage from the cells is induced by one of the above treatments. It does not appear to be due to de novo synthesis or proteolytic activation of 1,3-#-D-glucan synthase. It is concluded that this Ca24-dependent enzyme is directly activated by the influx of Ca24 occurring concomitantly with the leakage of cell constituents. This suggestion is also discussed in conjunction with the chitosan-induced synthesis of phytoalexin in the same cells.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca²⁺-Dependent Process

Köhle¹,

Jeblick²,

Poten³

et al. 1985

Plant Physiol.

342

143

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“…Plants confronted with a potential pathogen use a variety of defense mechanisms (2). One well-characterized defense mechanism is the synthesis and accumulation of stress metabolites called phy- 'Supported by the United States Department of Energy (DE-AC02- 76ERO-1426) and The Rockefeller Foundation (RF79049).…”

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confidence: 99%

“…Various compounds isolated from microorganisms have been found to have elicitor activity (reviewed in 1,2,6,37). Molecules derived from plant tissues also induce phytoalexin accumulation (14-16, 23, 28).…”

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confidence: 99%

Host-Pathogen Interactions

Davis¹,

Darvill²,

Albersheim³

et al. 1986

Plant Physiol.

159

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Recent studies have demonstrated that an apparently homogeneous preparation of an a-1,4-D-endopolyplacturonic acid lyase (EC 4.2.2.2) isolated from the phytopathogenic bacterium Erwinia carotovora induced phytoalexin accumulation in cotyledons of soybean (Glycine max jL.1Merr. cv Wayne) and that this pectin-degrading enzyme released heatstable elicitors of phytoalexins from soybean cell walls, citrus pectin, and sodium polypectate Plant Physiol 74: 52-60). The present paper reports the purification, by anion-exchange chromatography on QAE-Sephadex columns followed by gel-permeation chromatography on a Bio-Gel P6 column, of the two fractions with highest specific elicitor activity present in a crude elicitor-preparation obtained by lyase treatment of sodium polypectate. Structural analysis of the fraction with highest specific elicitor activity indicated that the major, if not only, component was a decasaccharide of a-1,4-D-galactosyluronic acid that contained the expected product of lyase cleavage, 4-deoxy-,6-L-5-threohexopyranos-4-enyluronic acid (4,5-unsaturated galactosyluronic acid), at the nonreducing terminus. This modified decagalacturonide fraction exhibited half-maximum and maximum elicitor activity at 1 microgram/ cotyledon (6 micromolar) and 5 micrograms/cotyledon (32 micromolar) plactosyluronic acid equivalents, respectively. Reducing 90 to 95% of the carboxyl groups of the galactosyluronic acid residues abolished the elicitor activity of the decagalacturonide fraction. The second most elicitor-active fraction contained mostly undeca-a-1,4-D-galactosyluronic acid that contained 4,5-unsaturated gaactosyluronic acid at the nonreducing termini. This fraction exhibited half-maximum and maximum elicitor activity at approximately 3 micrograms/cotyledon (17 micromolar) and 6 micrograms/cotyledon (34 micromolar) galactosyluronic acid equivalents, respectively. These results confirm and extend previous observations that oligogalacturonides derived from the pectic polysaccharides of plant cell walls can serve as regulatory molecules that induce phytoalexin accumulation in soybean. These results are consistent with the hypothesis that oligogalacturonides play a role in disease resistance in plants. Although (1, 1 1). Phytoalexins are a diverse group of compounds of low mol wt that have broad antibiotic activity against many prokaryotic and eukaryotic organisms (32, 36). In some hostpathogen combinations, phytoalexins accumulate at the site of attempted infection rapidly enough and in sufficient concentration to prevent further growth of the invading microorganism (19,24).Phytoalexin accumulation is also induced by molecules called elicitors. Various compounds isolated from microorganisms have been found to have elicitor activity (reviewed in 1, 2, 6, 37). Molecules derived from plant tissues also induce phytoalexin accumulation (14-16, 23, 28).Recent work has demonstrated that a heat-labile elicitor of phytoalexins produced by the phytopathogenic bacterium Erwinia carotovora var carotovora is a p...

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Oligoglucoside elicitor-mediated activation of plant defense

Ebel

1998

Bioessays

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Biochemical Mechanisms of Disease Resistance

Cited by 450 publications

References 143 publications

Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca²⁺-Dependent Process

Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca²⁺-Dependent Process

Host-Pathogen Interactions

Oligoglucoside elicitor-mediated activation of plant defense

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Biochemical Mechanisms of Disease Resistance

Cited by 450 publications

References 143 publications

Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca2+-Dependent Process

Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca2+-Dependent Process

Host-Pathogen Interactions

Oligoglucoside elicitor-mediated activation of plant defense

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Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca²⁺-Dependent Process

Chitosan-Elicited Callose Synthesis in Soybean Cells as a Ca²⁺-Dependent Process