Non-specific Toxins

Rudolph, K.

doi:10.1007/978-3-642-66279-9_12

Cited by 58 publications

(33 citation statements)

References 196 publications

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“…Vascular wilt pathogens are known to produce macromolecules within the vascular system of host plants (6). These macromolecules have generally been considered to be phytotoxins.…”

Section: Discussionmentioning

confidence: 99%

“…If large amounts of a big molecule enter the xylem, plugging will occur. Plant pathologists, however, have identified many macromolecules that induce wilt in plant cuttings within 2 h at concentrations as low as 50 ug/ml (6). It has been assumed that molecules in such low concentrations could not be merely plugging the vascular system and, as a result, they were classed as phytotoxins.…”

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confidence: 99%

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Susceptibility of Plants to Vascular Disruption by Macromolecules

Alfen

Allard-Turner²

1979

Plant Physiol.

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The xylem of alfalfa (Medicago sativa L.) was found to be susceptible to vascular obstruction by picomole quantities of dextrans. Not all parts of the xylem were equally susceptible to this plugging. The quantity ofdextran of 2 x 10' molecular weight required to stop vascular flow was 8 picomoles in petiole junctions and OA picomole in leaflet veins. Vascular Macromolecules in a plant's xylem are known to induce wilting (5). If large amounts of a big molecule enter the xylem, plugging will occur. Plant pathologists, however, have identified many macromolecules that induce wilt in plant cuttings within 2 h at concentrations as low as 50 ug/ml (6). It has been assumed that molecules in such low concentrations could not be merely plugging the vascular system and, as a result, they were classed as phytotoxins.Van Alfen and Turner showed that two of these large phytotoxins, produced respectively by Corynebacterium insidiosum (8) and Ceratocystis ulmi (9), act by interfering with water conduction in the plant's vascular system and not by any direct toxicity to plant cells. The decrease in vascular conductance through stems of the wilted cuttings caused by these macromolecules was not large.The flow of liquid through stems was reduced to about 20%o of its normal value (9). Such a reduction in liquid flow conductance is not sufficient to cause wilt (2). There was no question that the macromolecules had a significant effect on vascular conductance and it was assumed that their greatest effect on conductance was in locations other than in the stems.The work reported in this paper was initiated to determine if different components of a plant's vascular system differ in susceptibility to plugging by small amounts of macromolecules. MATERIALS AND METHODSNine-month-old DuPuits variety of alfalfa (Medicago sativa L.) grown in the greenhouse from seed was used in these studies.Vascular conductance of stems and petioles as well as the petiole junction was determined using previously described methods (9). To determine conductance of the vascular system to dextran solutions, the conductance of water through the system was first determined. This was followed by the dextran solution. As a 'Supported in part by National Science Foundation Grant PCM 77-08388.2 Joumal paper 2306, Utah Agricultural Experiment Station.control, the conductance of water followed by water rather than a dextran solution was determined. All dextran conductance data could then be expressed as a percentage of the conductance of water through the same section of the vascular system. The solutions used in these studies were prepared by dissolving dextrans obtained from Pharmacia Fine Chemicals in distilled H20. The water had previously been filtered through a 0.45-,um diameter filter (Millipore Corp.) and then degassed. The dextrans were normally used at a concentration of 800 ,ug/ml.Conductance of water through alfalfa leaflets could not be determined using a volumetric method so a gravimetric method was employed. Cuts were made about one-fourth of th...

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“…Vascular wilt pathogens are known to produce macromolecules within the vascular system of host plants (6). These macromolecules have generally been considered to be phytotoxins.…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Susceptibility of Plants to Vascular Disruption by Macromolecules

Alfen

Allard-Turner²

1979

Plant Physiol.

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“…Phytotoxins are microbial metabolities which, at low concentratioris, are harmful to plants [1 ]. Verticillium spp., a causal agent of fungal wilt in numerous plants, elaborates in culture phytotoxic proteinlipopolysaccharide (PLP) complexes of high M r (~3 × 10 6) [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Isolation and partial characterization of a phytotoxic glycopeptide from a protein—lipopolysaccharide complex produced by a potato isolate of Verticillium dahliae

1982

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“…It is also hard to imagine that enhanced permeability and increased leakage of water out of the plant cells would result in persistent water-soaking, as such water would soon be lost by transpiration resulting in dried or necrotized tissue. This effect is caused by several toxins of plant pathogens [14]. It would seem more likely, there fore, that water, which travels through the leaves with the transpiration stream, is captured by the EPS in the intercellular spaces.…”

Section: Discussionmentioning

confidence: 99%

The fate of extracellular polysaccharide from Pseudomonas phaseolicola in leaves and leaf extracts from halo-blight susceptible and resistant bean plants (Phaseofus vulgaris L.)

El-Banoby

Rudolph

Mendgen

1981

Physiological Plant Pathology

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Purified extracellular polysaccharide (EPS) from Pseudomonas phaseolu:ola was infiltrated into the mesophyll of bush bean leaves (Phaseolus vulgaris L.). The EPS disappeared from the intercellular spaces of the halo-blight resistant breeding line 02 12 h after infiltration. Simul taneously, the visible water-soaked spots had vanished. By contrast, the intercellular spaces of the halo-blight susceptible cultivar Red Kidney were still completely filled with EPS 3 days after infiltration, and the water-soaked leaf-areas persisted. The EPS formed a stable network in the intercellular spaces of Red Kidney, whereas small f10ccules were observed in , the incompatible system.In vitro studies showed that the intercellular fluid (IF) from the trifoliates of breeding line 02 partially degraded the EPS, whereas IF from cultivar Red Kidney did not. EPS which had been incubated with IF from resistant leaves completely lost its capacity to induce persistent water-soaked spots. It is cORc1uded, therefore, that the resistance of bean leaves towards persistent water-soaking caused by bacterial EPS was due to enzymatic degradation and inactivation of the introduced EPS.

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Non-specific Toxins

Cited by 58 publications

References 196 publications

Susceptibility of Plants to Vascular Disruption by Macromolecules

Susceptibility of Plants to Vascular Disruption by Macromolecules

Isolation and partial characterization of a phytotoxic glycopeptide from a protein—lipopolysaccharide complex produced by a potato isolate of Verticillium dahliae

The fate of extracellular polysaccharide from Pseudomonas phaseolicola in leaves and leaf extracts from halo-blight susceptible and resistant bean plants (Phaseofus vulgaris L.)

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