Dataset Information

Identification and characterization of the ergochrome gene cluster in the plant pathogenic fungus Claviceps purpurea.

ABSTRACT: BACKGROUND:Claviceps purpurea is a phytopathogenic fungus infecting a broad range of grasses including economically important cereal crop plants. The infection cycle ends with the formation of the typical purple-black pigmented sclerotia containing the toxic ergot alkaloids. Besides these ergot alkaloids little is known about the secondary metabolism of the fungus. Red anthraquinone derivatives and yellow xanthone dimers (ergochromes) have been isolated from sclerotia and described as ergot pigments, but the corresponding gene cluster has remained unknown. Fungal pigments gain increasing interest for example as environmentally friendly alternatives to existing dyes. Furthermore, several pigments show biological activities and may have some pharmaceutical value. RESULTS:This study identified the gene cluster responsible for the synthesis of the ergot pigments. Overexpression of the cluster-specific transcription factor led to activation of the gene cluster and to the production of several known ergot pigments. Knock out of the cluster key enzyme, a nonreducing polyketide synthase, clearly showed that this cluster is responsible for the production of red anthraquinones as well as yellow ergochromes. Furthermore, a tentative biosynthetic pathway for the ergot pigments is proposed. By changing the culture conditions, pigment production was activated in axenic culture so that high concentration of phosphate and low concentration of sucrose induced pigment syntheses. CONCLUSIONS:This is the first functional analysis of a secondary metabolite gene cluster in the ergot fungus besides that for the classical ergot alkaloids. We demonstrated that this gene cluster is responsible for the typical purple-black color of the ergot sclerotia and showed that the red and yellow ergot pigments are products of the same biosynthetic pathway. Activation of the gene cluster in axenic culture opened up new possibilities for biotechnological applications like the dye production or the development of new pharmaceuticals.

SUBMITTER: Neubauer L

PROVIDER: S-EPMC5611617 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Identification and characterization of the ergochrome gene cluster in the plant pathogenic fungus <i>Claviceps purpurea</i>.

Neubauer Lisa L Dopstadt Julian J Humpf Hans-Ulrich HU Tudzynski Paul P

Fungal biology and biotechnology 20160322

<h4>Background</h4><i>Claviceps purpurea</i> is a phytopathogenic fungus infecting a broad range of grasses including economically important cereal crop plants. The infection cycle ends with the formation of the typical purple-black pigmented sclerotia containing the toxic ergot alkaloids. Besides these ergot alkaloids little is known about the secondary metabolism of the fungus. Red anthraquinone derivatives and yellow xanthone dimers (ergochromes) have been isolated from sclerotia and describe ...[more]

PMID: 28955461

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Project description:Pseudocercospora fijiensis, causal agent of black Sigatoka of banana, produces polyketide synthase (PKS) pathways shown to be important in disease development by related Dothideomycete fungi. Genome analysis of the P. fijiensis PKS8-1 gene identified it as part of a gene cluster including genes encoding two transcription factors, a regulatory protein, a glyoxylase/beta-lactamase-like protein, an MFS transporter, a cytochrome P450, two aldo/keto reductases, a dehydrogenase, and a decarboxylase. Genome analysis of the related pathogens Pseudocercospora musae, Pseudocercospora eumusae, and Pseudocercospora pini-densiflorae, identified orthologous clusters containing a nearly identical combination of genes. Phylogenetic analysis of PKS8-1 identified homology to PKS proteins in the monodictyphenone and cladofulvin pathways in Aspergillus nidulans and Cladosporium fulvum, respectively. Analysis of clustered genes showed that the PKS8-1 cluster shares genes for enzymes involved in the production of the emodin intermediate in the monodictyphenone and cladofulvin pathways, but differs in many genes, suggesting production of a different metabolic product. Time course analysis of gene expression in infected banana showed up-regulation of PKS8-1 and four of eight clustered genes as early as 2 weeks post-inoculation and remaining high through 9 weeks. Overexpression of the pathway through constitutive expression of an aflR-like transcription factor gene in the cluster resulted in increased expression in culture of PKS8-1 as well as the four clustered genes that are up-regulated in infected plants. No differences were seen in timing or severity of disease symptoms with the overexpression strains relative to controls, however gene expression analysis showed no difference in expression in planta by an overexpression strain relative to controls. Thus constitutive expression of the aflR-like gene is not sufficient to upregulate the pathway above normal expression in planta. Pathway expression during all phases of disease development and conservation of the pathway in related Pseudocercospora species support a role for this pathway in disease.

Project description:Abstract The ergot diseases of agricultural and nonagricultural grasses are caused by the infection of Claviceps spp. (Hypocreales, Ascomycota) on florets, producing dark spur?like sclerotia on spikes that are toxic to humans and animals, leading to detrimental impacts on agriculture and economy due to the downgrading of cereal grains, import–export barriers, reduced yield, and ecological concerns. At least seven phylogenetic lineages (phylogenetic species) were identified within the premolecular concept of C. purpurea s.l. (sensu lato) in agricultural areas and vicinities in Canada and the Western United States. Claviceps purpurea s.s (sensu stricto) remained as the most prevalent species with a wide host range, including cereal crops, native, invasive, and weedy grasses. The knowledge on genetic diversity and distribution of C. purpurea s.s. in North America is lacking. The objective of the present study was to shed light on genetic differentiation and evolution of the natural populations of C. purpurea s.s. Multilocus DNA sequences of samples from Canada and the Western USA were analyzed using a phylogenetic network approach, and population demographic parameters were investigated. Results showed that three distinct genetically subdivided populations exist, and the subdivision is not correlated with geographic or host differentiations. Potential intrinsic mechanisms that might play roles in leading to the cessation of gene flows among the subpopulations, that is, mating and/or vegetative incompatibility, genomic adaptation, were discussed. The neutrality of two house?keeping genes that are widely used for DNA barcoding, that is, translation elongation factor 1?? (TEF1??) and RNA polymerase II second largest subunit (RPB2), was challenged and discussed. Regardless of the frequent sexuality and multiple modes of dispersal, the population of the toxigenic plant pathogen, Claviceps purpurea, that infects wide range of agricultural and nonagricultural grasses, was subdivided in nature. The population structure shed light on the underline mechanisms that might have led to the cessation of gene flow among subdivided populations. House?keeping gene markers were not neutral in certain circumstances.

Dataset Information

Identification and characterization of the ergochrome gene cluster in the plant pathogenic fungus Claviceps purpurea.

Publications

Identification and characterization of the ergochrome gene cluster in the plant pathogenic fungus <i>Claviceps purpurea</i>.

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