Host-selective toxins: agents of compatibility.

Walton, Jonathan D.

doi:10.1105/tpc.8.10.1723

Cited by 284 publications

(100 citation statements)

References 55 publications

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“…The resulting fractions are then used in a bioassayguided procedure to isolate and identify the pure phytotoxic metabolites (Barash et al 1981;Cotty et al 1983;Gamboa-Angulo et al 2000). With this strategy, more than 200 HSTs and non-HSTs have been isolated (Huang 2001;Panigrahi 1997;Rudolph 1976;Walton 1996;Wood et al 1992). Nevertheless, a significant number of the metabolites that are currently considered to be phytotoxins have not been properly characterized in terms of their role during the plant-pathogen interaction (Knoche and Duvick 1987).…”

Section: Introductionmentioning

confidence: 99%

Is zinniol a true phytotoxin? Evaluation of its activity at the cellular level against Tagetes erecta

et al. 2010

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Zinniol, a non-host selective phytotoxin commonly produced by fungi of the Alternaria genus, has been reported as the metabolite responsible for the phytotoxicity of the lipophilic fraction of A. tagetica. While both the lipophilic fraction and zinniol have been shown to produce necrosis on leaves of susceptible marigold (Tagetes erecta) plants, the true role of zinniol in the infectious process remains uncertain. Using marigold cell cultures as a model, we evaluated the effects of zinniol and the lipophilic fraction at the cellular level and showed that pure zinniol is not markedly phytotoxic at concentrations known to induce necrosis in leaves of T. erecta. Moreover, the effects of zinniol on cell membranes and DNA fragmentation are less intense than those caused by the lipophilic fraction. These results suggest that zinniol may not play a significant role in the A. tagetica-T. erecta interaction and, consequently, its classification as a non-host selective phytotoxin is questionable.

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Section: Introductionmentioning

confidence: 99%

Is zinniol a true phytotoxin? Evaluation of its activity at the cellular level against Tagetes erecta

et al. 2010

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“…These metabolites have been classified as host selective (HSTs) and nonhost selective phytotoxins (nonHSTs) based on their role in pathogenesis (Anonymous 2003). While HSTs are required for the pathogen to colonize the plant and are toxic only to hosts of the pathogen that produces them (Graniti 1991;Kohmoto and Otani 1991;Markham and Hille 2001;Scheffer and Livingston 1984;Walton 1996;Wolpert et al 2002), non-HSTs are not essential for pathogenesis, but they contribute to virulence, and their toxicity is not congruent with the patterns of resistance and susceptibility in the host (Ballio 1991;Graniti 1991;Knoche and Duvick 1987;Mitchell 1984).…”

Section: Introductionmentioning

confidence: 97%

Physiological effects of the hydrophilic phytotoxins produced by Mycosphaerella fijiensis, the causal agent of black sigatoka in banana plants

et al. 2010

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Although Mycosphaerella fijiensis, the causal agent of black sigatoka disease of banana, has been known to produce numerous lipophilic host-selective (HSTs) and nonhost selective phytotoxins (non-HSTs), only recently we have reported that the pathogen also produces hydrophilic phytotoxins. Here we examined the effect of light on the toxicity of the hydrophilic phytotoxins and estimated the electrolyte leakage and H 2 O 2 and superoxide generation in detached banana leaves to study their mode of action at the cellular level. Nonhost plant species were also tested to determine whether the toxins are HSTs or nonHSTs. Our results suggest that the hydrophilic phytotoxins are non-HSTs, that their phytotoxicity is not light dependent, and that they may act at the plasma membrane by altering permeability through oxidative damage, by inducing ROS production as part of their mechanism of action.

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“…Isolates of the ascomycete Cochliobolus carbonum that produce the cyclic tetrapeptide HC-toxin (cyclo[DPro-L-Ala-D-Ala-L-Aeo], where Aeo stands for 2-amino-9,10-epoxi-8-oxodecanoic acid) are speci®cally virulent on maize lines that are homozygous for the recessive allele of Hm (Walton 1996). Isolates of C. carbonum that do not produce HC-toxin (Tox2 A ) are only weakly pathogenic regardless of the host genotype, and maize lines with the dominant allele of Hm are insensitive to HC-toxin and resistant to HC-toxin-producing (Tox2 + ) isolates of the fungus (Meeley et al 1992;Walton and Panaccione 1993).…”

Section: Introductionmentioning

confidence: 99%

Regulation of cyclic peptide biosynthesis and pathogenicity in Cochliobolus carbonum by TOXEp, a novel protein with a bZIP basic DNA-binding motif and four ankyrin repeats

Ahn¹,

Jd²

1998

Mol Gen Genet

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HC-toxin is an epoxide-containing cyclic tetrapeptide that is a critical virulence determinant in the pathogenic interaction between the ®lamentous fungus Cochliobolus carbonum and maize. HC-toxin exerts a potent cytostatic eect on plant and animal cells by inhibiting histone deacetylase. The biosynthesis of HC-toxin by C. carbonum is controlled by a complex genetic locus, TOX2, that contains multiple, duplicated copies of genes encoding export and biosynthetic enzymes. A new gene in the TOX2 complex, TOXE, has now been isolated. Mutation of TOXE by targeted gene disruption has no eect on growth and sporulation but abolishes HC-toxin production and pathogenicity. TOXE is required for the expression of three genes with a known or putative role in HC-toxin production, but is not required for expression of HTS1, which encodes the large, multifunctional peptide synthetase that is the central enzyme in HC-toxin biosynthesis. At its N-terminus, TOXEp has a bZIP basic DNA binding domain, but it does not contain any discernible leucine zipper or helix-loop-helix. At its carboxy terminus, TOXEp contains four ankyrin repeats. In having these two common regulatory motifs in a single polypeptide, TOXEp appears to represent a novel class of regulatory protein.TOXE is present only in HC-toxin-producing (Tox2 + ) isolates of C. carbonum. Most Tox2 + isolates have two copies; in strain SB111, one copy of TOXE is on the same 3.5-Mb chromosome that contains all of the other genes known to be involved in HC-toxin biosynthesis, and the second copy of TOXE is on a 0.7-Mb chromosome.

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Host-selective toxins: agents of compatibility.

Cited by 284 publications

References 55 publications

Is zinniol a true phytotoxin? Evaluation of its activity at the cellular level against Tagetes erecta

Is zinniol a true phytotoxin? Evaluation of its activity at the cellular level against Tagetes erecta

Physiological effects of the hydrophilic phytotoxins produced by Mycosphaerella fijiensis, the causal agent of black sigatoka in banana plants

Regulation of cyclic peptide biosynthesis and pathogenicity in Cochliobolus carbonum by TOXEp, a novel protein with a bZIP basic DNA-binding motif and four ankyrin repeats

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