Biological and immunochemical characterization of a low molecular weight phytotoxin isolated from a protein—lipopolysaccharide complex produced by a potato isolate of Verticillium dahliae Kleb

Nachmias, A.; Buchner, Virginia; Burstein, Yigal

doi:10.1016/0048-4059(85)90029-3

Cited by 48 publications

(30 citation statements)

References 11 publications

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“…The strongest evidence came from a heat-stable, protein-lipopolysaccharide complex recovered from the culture filtrates of various V. dahliae isolates that caused vascular discoloration and wilting in susceptible hosts (34,40), and when isolated from race 1 and race 2 isolates caused a differential host reaction when infiltrated into tomato near-isogenic lines with or without the Ve resistance genes (41). Further purification of this protein-lipopolysaccharide complex identified a 3-kDa peptide with high activity (9,39). Recently, Wang and colleagues (60) identified a V. dahliae necrosis and ethyleneeliciting protein (VdNEP) while screening an expressed sequence tag library for cDNAs that encoded putative secreted proteins.…”

Section: Discussionmentioning

confidence: 99%

Colonization of Resistant and Susceptible Lettuce Cultivars by a Green Fluorescent Protein-Tagged Isolate of Verticillium dahliae

Vallad

Subbarao²

2008

Phytopathology®

148

109

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Interactions between lettuce and a green fluorescent protein (GFP)-expressing, race 1 isolate of Verticillium dahliae, were studied to determine infection and colonization of lettuce cultivars resistant and susceptible to Verticillium wilt. The roots of lettuce seedlings were inoculated with a conidial suspension of the GFP-expressing isolate. Colonization was studied with the aid of laser scanning confocal and epi-fluorescence microscopes. Few differences in the initial infection and colonization of lateral roots were observed between resistant and susceptible cultivars. Hyphal colonies formed on root tips and within the root elongation zones by 5 days, leading to the colonization of cortical tissues and penetration of vascular elements regardless of the lettuce cultivar by 2 weeks. By 8 to 10 weeks after inoculation, vascular discoloration developed within the taproot and crown regions of susceptible cultivars well in advance of V. dahliae colonization. Actual foliar wilt coincided with the colonization of the taproot and crown areas and the eruption of mycelia into surrounding cortical tissues. Advance colonization of stems, pedicels, and inflorescence, including developing capitula and mature achenes was observed. Seedborne infection was limited to the maternal tissues of the achene, including the pappus, pericarp, integument, and endosperm; but the embryo was never compromised. Resistant lettuce cultivars remained free of disease symptoms. Furthermore, V. dahliae colonization never progressed beyond infected lateral roots of resistant cultivars. Results indicated that resistance in lettuce may lie with the plant's ability to shed infected lateral roots or to inhibit the systemic progress of the fungus through vascular tissues into the taproot.

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Section: Discussionmentioning

confidence: 99%

Colonization of Resistant and Susceptible Lettuce Cultivars by a Green Fluorescent Protein-Tagged Isolate of Verticillium dahliae

Vallad

Subbarao²

2008

Phytopathology®

148

109

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“…Buchner et al (8) found that a potato isolate of V. dahliae produced a highmolecular-mass protein-lipopolysaccharide complex (PLPC) which was associated with pathogenicity. A low-molecularmass (Ͻ3-kDa) phytotoxic polypeptide fraction was partially purified from this PLPC, and it was found that the chlorosisinducing activity of the PLPC was due mainly to this small peptide (29). From cotton isolate, a PLPC of 197 kDa was found to induce necrosis and wilting in cotton seedlings and also stimulated phenylalanine ammonia-lyase activity and phytoalexin biosynthesis in cotton suspension cells.…”

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confidence: 99%

VdNEP, an Elicitor from Verticillium dahliae , Induces Cotton Plant Wilting

Wang

Cai

Gou

et al. 2004

Appl Environ Microbiol

128

110

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Verticillium wilt is a vascular disease of cotton. The causal fungus, Verticillium dahliae, secretes elicitors in culture. We have generated ϳ1,000 5-terminal expressed sequence tags (ESTs) from a cultured mycelium of V. dahliae. A number of ESTs were found to encode proteins harboring putative signal peptides for secretion, and their cDNAs were isolated. Heterologous expression led to the identification of a protein with elicitor activities. This protein, named V. dahliae necrosis-and ethylene-inducing protein (VdNEP), is composed of 233 amino acids and has high sequence identities with fungal necrosis-and ethylene-inducing proteins. Infiltration of the bacterially expressed His-VdNEP into Nicotiana benthamiana leaves resulted in necrotic lesion formation. In Arabidopsis thaliana, the fusion protein also triggered production of reactive oxygen species and induced the expression of PR genes. When added into suspension cultured cells of cotton (Gossypium arboreum), the fusion protein elicited the biosynthesis of gossypol and related sesquiterpene phytoalexins at low concentrations, and it induced cell death at higher concentrations. On cotton cotyledons and leaves, His-VdNEP induced dehydration and wilting, similar to symptoms caused by a crude preparation of V. dahliae elicitors. Northern blotting showed a low level of VdNEP expression in the mycelium during culture. These data suggest that VdNEP is a wilt-inducing factor and that it participates in cotton-V. dahliae interactions.Recognition plays a central role in interactions between plants and their pathogens. Successful pathogens must be able to recognize and overcome host-plant defense responses. Plants also have evolved sophisticated mechanisms to detect a multitude of potential pathogens in their natural environments and to activate diverse defense mechanisms (15). Elicitors are molecules that trigger defense responses in plants, and they play significant roles in the signal exchange between plants and pathogens (33). Diverse plant defense responses induced by elicitors involve de novo synthesis and accumulation of antimicrobial phytoalexins (11, 16), induction of cell death (hypersensitive response) (6, 17, 44), production of activated oxygen species (oxidative burst) (4, 13), and modification of plant cell walls by deposition of callose (41). The structural and cultivar specificity of elicitors and their ability to trigger plant defense responses at very low concentrations strongly suggest the existence of receptors at the plant plasma membrane and a downstream signal transduction cascade (12).Verticillium dahliae Kleb. is a phytopathogenic fungus that causes wilt disease in a wide range of crops (34), including cotton. The fungus is widespread in most cotton-growing areas and is a major threat to cotton production. Many reports have shown that V. dahliae produces both low-and high-molecularweight phytotoxic metabolites in culture fluids; these secreted substances behave as elicitors inducing phytoalexin formation, as well as the formation of phytotoxin...

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“…A major problem associated with the evaluation of somaclonal variation for disease resistance is the availability of efficient, reliable screening methods. Verticillium culture filtrate contains toxic metabolites Nachmias et al, 1982Nachmias et al, , 1985Nachmias et al, , 1987 which may be useful to select Verticillium-resistant plants (Nachmias et al, 1990). Our results demonstrate that the fungal filtrate assayed on cultured single node explants enables a discrimination between tolerant (D6sir6e) and resistant (Kondor) cultivars (Table 1).…”

Section: Discussionmentioning

confidence: 67%

“…This approach is necessary when the pathogenetic mechanism is not clear or fungal disease is expressed only in organized tissues (Daub, 1986). V. dahliae toxin does not diffuse in potato tissues and cytoimmunofluorescence studies in tubers and stems infected by the fungus demonstrated that the toxin was localized on the walls of the xylem vessels (Nachmias et al, 1985;Buchner et al, 1989). A recent report on the reaction of potato tissue cultures to V. dahliae Vd toxin asserted that calli were unaffected, except for the cells in direct contact with the toxic medium (Nachmias et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

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Somaclonal variation for resistance to Verticillium dahliae in potato (Solanum tuberosum L.) plants regenerated from callus

et al. 1994

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Plant tissue culture is recognized as an important tool to generate useful genetic variability for crop improvement. Regenerated plants from callus induced from stem explants of Solanum tuberosum cv D6sir6e were assessed by in vitro selection, for resistance to Verticillium dahliae. This fungus is the causal agent of Verticillium wilt, a serious vascular wilt disease both in crops and wild species.The rate of in vitro multiplication by single node cuttings was used as a parameter of screening in two selection cycles with different concentrations of V. dahliae filtrate. One resistant clone was selected and then evaluated by inoculation in the growth chamber. Induced damage, and morphological traits (dry weight, leaf area and tuber production) were estimated. The selected clone was comparable to the resistant control, cv Kondor.The results suggest that genetic variation induced in tissue culture could be utilized to generate disease resistance.

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Biological and immunochemical characterization of a low molecular weight phytotoxin isolated from a protein—lipopolysaccharide complex produced by a potato isolate of Verticillium dahliae Kleb

Cited by 48 publications

References 11 publications

Colonization of Resistant and Susceptible Lettuce Cultivars by a Green Fluorescent Protein-Tagged Isolate of Verticillium dahliae

Colonization of Resistant and Susceptible Lettuce Cultivars by a Green Fluorescent Protein-Tagged Isolate of Verticillium dahliae

VdNEP, an Elicitor from Verticillium dahliae , Induces Cotton Plant Wilting

Somaclonal variation for resistance to Verticillium dahliae in potato (Solanum tuberosum L.) plants regenerated from callus

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