Solanapyrones A, B and C, phytotoxic metabolites from the fungus Alternaria solani

Ichihara, Akitami; Tazaki, Hiroyuki; Sakamura, Sadao

doi:10.1016/s0040-4039(00)87872-7

Cited by 124 publications

(89 citation statements)

References 10 publications

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“…After 18 days, the cultures were filtered through four layers of Miracloth (Calbiochem, USA) in a vacuum to remove the mycelium. The mycelium in each flask was dried to determine its dry weight, and solanapyrones in the culture filtrates were extracted using Sep-Pak Vac 6 cc (1-g) tC 18 cartridges (Waters Corp., Milford, MA, USA). Individual cartridges were eluted with 2 ml of methanol, and the eluents were subjected to liquid chromatography (LC)-mass spectrometry analysis.…”

Section: Methodsmentioning

confidence: 99%

“…Solanapyrones are polyketide-derived SMs that were originally found in the plant-pathogenic fungi Alternaria solani and Ascochyta rabiei (17,18), as well as in some other ascomycetous fungi occupying different ecological niches (19)(20)(21). The fact that solanapyrones are produced by distantly related species like Nigrospora (Sordariomycetes) but not by closely related species of Ascochyta or Alternaria (Dothideomycetes) suggests the acquisition of the entire gene cluster by horizontal gene transfer (HGT) events.…”

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confidence: 99%

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A Novel Type Pathway-Specific Regulator and Dynamic Genome Environments of a Solanapyrone Biosynthesis Gene Cluster in the Fungus Ascochyta rabiei

et al. 2015

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c Secondary metabolite genes are often clustered together and situated in particular genomic regions, like the subtelomere, that can facilitate niche adaptation in fungi. Solanapyrones are toxic secondary metabolites produced by fungi occupying different ecological niches. Full-genome sequencing of the ascomycete Ascochyta rabiei revealed a solanapyrone biosynthesis gene cluster embedded in an AT-rich region proximal to a telomere end and surrounded by Tc1/Mariner-type transposable elements. The highly AT-rich environment of the solanapyrone cluster is likely the product of repeat-induced point mutations. Several secondary metabolism-related genes were found in the flanking regions of the solanapyrone cluster. Although the solanapyrone cluster appears to be resistant to repeat-induced point mutations, a P450 monooxygenase gene adjacent to the cluster has been degraded by such mutations. Among the six solanapyrone cluster genes (sol1 to sol6), sol4 encodes a novel type of Zn(II)2Cys6 zinc cluster transcription factor. Deletion of sol4 resulted in the complete loss of solanapyrone production but did not compromise growth, sporulation, or virulence. Gene expression studies with the sol4 deletion and sol4-overexpressing mutants delimited the boundaries of the solanapyrone gene cluster and revealed that sol4 is likely a specific regulator of solanapyrone biosynthesis and appears to be necessary and sufficient for induction of the solanapyrone cluster genes. Despite the dynamic surrounding genomic regions, the solanapyrone gene cluster has maintained its integrity, suggesting important roles of solanapyrones in fungal biology.T he subtelomere, the region upstream of the telomere on a linear chromosome, is characterized by richness in repetitive sequences and frequent chromosomal rearrangement and lacks synteny among closely related species and even within the same species in fungi (1-4). Subtelomeric regions are also enriched with duplicate, translocated, and horizontally transferred genes and thought to be evolutionarily labile and important for niche adaptation (2, 5, 6). These plastic chromosomal regions often include contingency genes, such as genes involved in membrane transport (2, 6), nutrient assimilation (2, 7), anaerobiosis (8), and virulence (1, 9, 10). Secondary metabolite (SM) gene clusters also exhibit a subtelomeric bias (11)(12)(13)(14).In fungi, SMs play diverse roles in host and niche specialization, serving as virulence factors, antibiotics, and metal ionchelating agents (15, 16). Solanapyrones are polyketide-derived SMs that were originally found in the plant-pathogenic fungi Alternaria solani and Ascochyta rabiei (17, 18), as well as in some other ascomycetous fungi occupying different ecological niches (19-21). The fact that solanapyrones are produced by distantly related species like Nigrospora (Sordariomycetes) but not by closely related species of Ascochyta or Alternaria (Dothideomycetes) suggests the acquisition of the entire gene cluster by horizontal gene transfer (HGT) events. Recently, th...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

A Novel Type Pathway-Specific Regulator and Dynamic Genome Environments of a Solanapyrone Biosynthesis Gene Cluster in the Fungus Ascochyta rabiei

et al. 2015

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“…SpA used in this study was purified from cultured fluid of A. solani as reported previously (Ichihara et al, 1983;Langsdorf et al, 1989). The fungus was grown in potato glucose medium at 25°C for 25 days.…”

Section: Spa Preparationmentioning

confidence: 99%

A phytotoxin Solanapyrone-A downregulates calcium-dependent protein kinase activity in potato

Hassan¹,

Hatsugai²,

Shah³

2013

Genet. Mol. Res.

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ABSTRACT. We previously demonstrated that alternaric acid, a host-specific toxin produced by the plant pathogenic fungus Alternaria solani, in the presence of Ca 2+ and Mg 2+ , stimulated in vitro phosphorylation of His-tagged calcium-dependent protein kinase 2 from potato cultivar Rishiri (RiCDPK2). Herein, we report that Solanapyrone-A (SpA), a non-host-specific toxin produced by A. solani, inhibited the phosphorylation of RiCDPK2 in the presence of Ca 2+ and Mg 2+ . However, SpA stimulated RiCDPK2 phosphorylation in the absence of these cations. Based on the current findings, we suggest that RiCDPK2 may mediate SpA-induced signaling independent of Ca 2+ and Mg 2+ , leading to a compatible interaction between potato and A. solani.

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“…42 Alternaria solani also produces other complex reduced-type polyketides, solanapyrones. [43][44][45] Biosynthetic studies strongly suggested that a biological Diels-Alder reaction is involved in formation of their decalin skeleton. [46][47][48] Chemical studies on Alternaria solani products were carried out by Professors Ichihara and Oikawa group of Hokkaido University including biosynthetic studies.…”

Section: Reducing-type Ipkss In Alternaria Solanimentioning

confidence: 99%

Functional analysis of fungal polyketide biosynthesis genes

Fujii

2010

J Antibiot

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Fungal polyketides have huge structural diversity from simple aromatics to highly modified complex reduced-type compounds. Despite such diversty, single modular iterative type I polyketide synthases (iPKSs) are responsible for their carbon skeleton construction. Using heterologous expression systems, we have studied on ATX, a 6-methylsalicylic acid synthase from Aspergillus terreus as a model iPKS. In addition, iPKS functions involved in fungal spore pigment biosynthesis were analyzed together with polyketide-shortening enzymes that convert products of PKSs to shorter ketides by hydrolytic C-C bond cleavage. In our studies on reducing-type iPKSs, we cloned and expressed PKS genes, pksN, pksF, pksK and sol1 from Alternaria solani. The sol gene cluster was found to be involved in solanapyrone biosynthesis and sol5 was identified to encode solanapyrone synthase, a Diels-Alder enzyme. Our fungal PKS studies were further extended to identify the function of PKS-nonribosomal peptide synthase involved in cyclopiazonic acid biosynthesis.

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Solanapyrones A, B and C, phytotoxic metabolites from the fungus Alternaria solani

Cited by 124 publications

References 10 publications

A Novel Type Pathway-Specific Regulator and Dynamic Genome Environments of a Solanapyrone Biosynthesis Gene Cluster in the Fungus Ascochyta rabiei

A Novel Type Pathway-Specific Regulator and Dynamic Genome Environments of a Solanapyrone Biosynthesis Gene Cluster in the Fungus Ascochyta rabiei

A phytotoxin Solanapyrone-A downregulates calcium-dependent protein kinase activity in potato

Functional analysis of fungal polyketide biosynthesis genes

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