The Accumulation of L-Ornithine in Halo-Blight Infected Bean Plants (Phaseolus vulgaris L.), Induced by the Toxin of the Pathogen Pseudomonas phaseolicola (Burkh.) Dowson

Rudolph, K.; Stahmann, Mark A.

doi:10.1111/j.1439-0434.1966.tb04709.x

Cited by 54 publications

(25 citation statements)

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“…The results so far indicate that OCT inhibition by the toxin is intimately related to chlorosis and that the reported (20,28) accumulation of ornithine is a result of the OCT inhibition. However, it is unlikely that OCT inhibition alone could be the cause of the abnormally high ornithine concentrations in affected tissues.…”

Section: Resultsmentioning

confidence: 87%

“…Chlorotic pathogen infected tissues show a 440-fold increase in ornithine content, while chlorotic toxin-treated tissues show a 106-fold increase (28). Since the ornithine pool in plants is usually small (1), this striking increase indicates a derangement in the normal ornithine metabolism of affected tissues.…”

mentioning

confidence: 99%

“…When bean plants (Phaseolus vulgaris L.) are infected by their pathogen Pseudomonas phaseolicola or injected with its toxic culture filtrates, they exhibit two symptoms: chlorosis and accumulation of ornithine (20,28). Chlorotic pathogen infected tissues show a 440-fold increase in ornithine content, while chlorotic toxin-treated tissues show a 106-fold increase (28).…”

Section: Introductionmentioning

confidence: 99%

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Mode of Action of the Toxin from Pseudomonas phaseolicola

1972

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The specificity of the Pseudomonas phaseolicola toxin for enzyme inhibition and its relationship to toxin-induced chlorosis in bean leaves (Phaseolus vulgaris L.) was examined. The toxin showed no significant inhibitory activity against glutamine synthetase, glutamine transferase, carbamyl phosphate synthetase, aspartate carbamoyltransferase, or arginase at concentrations 100-fold higher than that needed to inhibit ornithine carbamoyltransferase by 50%.Protection from and reversal of toxin-induced chlorosis in bean leaves was attempted with several amino acids. Aside from protection with L-citrulline which was previously reported, only L-arginine-HCl and to a minor extent L-leucine and L-glutamine showed protection from chlorosis. L-Citrulline and L-arginine-HCI (but not L-glutamine and L-leucine) also reversed toxininduced chlorosis.Ultrastructuraily, cells from toxin-treated chlorotic tissues showed no observable changes as compared to nontreated tissues. This, together with the ability of the two amino acids to reverse chlorosis, indicated that the toxin causes a reversible biochemical lesion in treated tissue.While tissues from bean plants inoculated with P. phaseolicola showed a large accumulation of ornithine, toxin-treated tissues showed no accumulation of ornithine. The latter finding indicated that in addition to the ornithine carbamoyltransferase inhibitor, the pathogen may produce inhibitors of other ornithine metabolizing enzymes in inoculated tissues.When bean plants (Phaseolus vulgaris L.) are infected by their pathogen Pseudomonas phaseolicola or injected with its toxic culture filtrates, they exhibit two symptoms: chlorosis and accumulation of ornithine (20,28). Chlorotic pathogen infected tissues show a 440-fold increase in ornithine content, while chlorotic toxin-treated tissues show a 106-fold increase (28). Since the ornithine pool in plants is usually small (1), this striking increase indicates a derangement in the normal ornithine metabolism of affected tissues.Ornithine is metabolized primarily through two pathways,

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Section: Resultsmentioning

confidence: 87%

mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mode of Action of the Toxin from Pseudomonas phaseolicola

1972

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“…Dowson, a pathogen of bean (Phaseolus vulgaris L.) produces an extracellular toxin which induces chlorotic haloes accompanied by accumulation of the amino acid ornithine (10,17). In the preceding communication (12), however, we reported that a toxin extracted from P. phaseolicola culture filtrates induces chlorosis, but not ornithine accumulation (12) MATERIALS AND METHODS Enzyme Preparation.…”

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confidence: 99%

Mode of Action of the Toxin from Pseudomonas phaseolicola

Tam

Patil

1972

Plant Physiol.

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“…Rudolph and Stahmann (9) showed that injection of the halo blight toxin into leaves produced two effects, a specific effect, accumulation of ornithine, and a nonspecific effect, chlorosis. Ornithine accumulation did not result when chlorosis was induced by other agents.…”

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confidence: 99%

Inhibition of Ornithin Carbamyl Transferase from Bean Plants by the Toxin of Pseudomonas phaseolicola

1970

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Pseudomonas phaseolicola (Burkh.) Dowson, a pathogen of bean (Phaseolus vulgaris L.) plants, causes chlorotic haloes in infected host leaves (7). In vitro the pathogen produces an extracellular toxin which when injected into bean leaves also produces chlorotic haloes (2). Whether the symptoms are caused by infection or by injection of toxin, ornithine accumulates in the chlorotic tissues (9). Here we present evidence which indicates that ornithine accumulation is caused by the inhibition of ornithine carbamyl transferase of the host by the toxin.Toxin Preparation. The halo blight toxin was partially purified from the culture filtrate of a virulent strain of P. phaseolicola grown in the YEP medium (9). Five hundred milliliters of the filtrate were concentrated to 20 ml under reduced pressure at 50 C, and the concentrate was desalted with 10 volumes of methanol.The extract was concentrated and the procedure repeated two more times. The final extract was evaporated to dryness and made up to 10 ml with distilled water. Four milliliters of this sample were applied to a 2-X 45-cm column of Sephadex G-10. The column was eluted with distilled water at a flow rate of 17.6 nl/hr (fraction volume, 2.2 ml). An identical batch of the medium, which was not inoculated, was subjected to the same procedure including incubation under the growth conditions, as a control and is designated nongrown. The culture filtrates are designated grown. Aliquots (25 ,ul) from every third fraction collected from the Sephadex column were assayed for halo-inducing activity on young trifoliate leaves of 4-week-old Red Kidney bean plants in a growth chamber (2). The same fractions were diluted 10-fold with distilled water and 80 Iul of the diluted fraction were used to test its inhibitory activity against OCT2 of bean leaves. To determine ve/vo (retention volume/void volume) of the active material, fractions with halo-inducing activity were concentrated to 2 ml and put on an analytical column (90 x 1.2 cm) of Sephadex G-10. The elution rate was 10.8 ml/hr (fraction volume, 1.8 ml).Enzyme Preparation. Acetone powder was prepared from trifoliate leaves of 3 to 4 week-old Red Kidney bean plants as described before (4). Five grams of the acetone powder were stirred for 1 hr in 90 ml of 0.1 M potassium phosphate buffer, pH 7.0, containing 5 X 10-3 M 2-mercaptoethanol. The slurry was cen-

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The Accumulation of L-Ornithine in Halo-Blight Infected Bean Plants (Phaseolus vulgaris L.), Induced by the Toxin of the Pathogen Pseudomonas phaseolicola (Burkh.) Dowson

Cited by 54 publications

References 21 publications

Mode of Action of the Toxin from Pseudomonas phaseolicola

Mode of Action of the Toxin from Pseudomonas phaseolicola

Mode of Action of the Toxin from Pseudomonas phaseolicola

Inhibition of Ornithin Carbamyl Transferase from Bean Plants by the Toxin of Pseudomonas phaseolicola

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