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Early development of Moniliophthora perniciosa basidiomata and developmentally regulated genes.

ABSTRACT: BACKGROUND:The hemibiotrophic fungus Moniliophthora perniciosa is the causal agent of Witches' broom, a disease of Theobroma cacao. The pathogen life cycle ends with the production of basidiocarps in dead tissues of the infected host. This structure generates millions of basidiospores that reinfect young tissues of the same or other plants. A deeper understanding of the mechanisms underlying the sexual phase of this fungus may help develop chemical, biological or genetic strategies to control the disease. RESULTS:Mycelium was morphologically analyzed prior to emergence of basidiomata by stereomicroscopy, light microscopy and scanning electron microscopy. The morphological changes in the mycelium before fructification show a pattern similar to other members of the order Agaricales. Changes and appearance of hyphae forming a surface layer by fusion were correlated with primordia emergence. The stages of hyphal nodules, aggregation, initial primordium and differentiated primordium were detected. The morphological analysis also allowed conclusions on morphogenetic aspects. To analyze the genes involved in basidiomata development, the expression of some selected EST genes from a non-normalized cDNA library, representative of the fruiting stage of M. perniciosa, was evaluated. A macroarray analysis was performed with 192 selected clones and hybridized with two distinct RNA pools extracted from mycelium in different phases of basidiomata formation. This analysis showed two groups of up and down-regulated genes in primordial phases of mycelia. Hydrophobin coding, glucose transporter, Rho-GEF, Rheb, extensin precursor and cytochrome p450 monooxygenase genes were grouped among the up-regulated. In the down-regulated group relevant genes clustered coding calmodulin, lanosterol 14 alpha demethylase and PIM1. In addition, 12 genes with more detailed expression profiles were analyzed by RT-qPCR. One aegerolysin gene had a peak of expression in mycelium with primordia and a second in basidiomata, confirming their distinctiveness. The number of transcripts of the gene for plerototolysin B increased in reddish-pink mycelium and indicated an activation of the initial basidiomata production even at this culturing stage. Expression of the glucose transporter gene increased in mycelium after the stress, coinciding with a decrease of adenylate cyclase gene transcription. This indicated that nutrient uptake can be an important signal to trigger fruiting in this fungus. CONCLUSION:The identification of genes with increased expression in this phase of the life cycle of M. perniciosa opens up new possibilities of controlling fungus spread as well as of genetic studies of biological processes that lead to basidiomycete fruiting. This is the first comparative morphologic study of the early development both in vivo and in vitro of M. perniciosa basidiomata and the first description of genes expressed at this stage of the fungal life cycle.

SUBMITTER: Pires AB

PROVIDER: S-EPMC2782264 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

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Early development of Moniliophthora perniciosa basidiomata and developmentally regulated genes.

Pires Acássia B L AB Gramacho Karina P KP Silva Delmira C DC Góes-Neto Aristóteles A Silva Mylene M MM Muniz-Sobrinho Jairo S JS Porto Ricardo F RF Villela-Dias Cristiano C Brendel Martin M Cascardo Júlio C M JC Pereira Gonçalo A G GA

BMC microbiology 20090804

<h4>Background</h4>The hemibiotrophic fungus Moniliophthora perniciosa is the causal agent of Witches' broom, a disease of Theobroma cacao. The pathogen life cycle ends with the production of basidiocarps in dead tissues of the infected host. This structure generates millions of basidiospores that reinfect young tissues of the same or other plants. A deeper understanding of the mechanisms underlying the sexual phase of this fungus may help develop chemical, biological or genetic strategies to co ...[more]

PMID: 19653910

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Project description:BackgroundThe hemibiotrophic pathogens Moniliophthora perniciosa (witches' broom disease) and Moniliophthora roreri (frosty pod rot disease) are among the most important pathogens of cacao. Moniliophthora perniciosa has a broad host range and infects a variety of meristematic tissues in cacao plants, whereas M. roreri infects only pods of Theobroma and Herrania genera. Comparative pathogenomics of these fungi is essential to understand Moniliophthora infection strategies, therefore the detection and in silico functional characterization of effector candidates are important steps to gain insight on their pathogenicity.ResultsCandidate secreted effector proteins repertoire were predicted using the genomes of five representative isolates of M. perniciosa subpopulations (three from cacao and two from solanaceous hosts), and one representative isolate of M. roreri from Peru. Many putative effectors candidates were identified in M. perniciosa: 157 and 134 in cacao isolates from Bahia, Brazil; 109 in cacao isolate from Ecuador, 92 and 80 in wild solanaceous isolates from Minas Gerais (Lobeira) and Bahia (Caiçara), Brazil; respectively. Moniliophthora roreri showed the highest number of effector candidates, a total of 243. A set of eight core effectors were shared among all Moniliophthora isolates, while others were shared either between the wild solanaceous isolates or among cacao isolates. Mostly, candidate effectors of M. perniciosa were shared among the isolates, whereas in M. roreri nearly 50% were exclusive to the specie. In addition, a large number of cell wall-degrading enzymes characteristic of hemibiotrophic fungi were found. From these, we highlighted the proteins involved in cell wall modification, an enzymatic arsenal that allows the plant pathogens to inhabit environments with oxidative stress, which promotes degradation of plant compounds and facilitates infection.ConclusionsThe present work reports six genomes and provides a database of the putative effectorome of Moniliophthora, a first step towards the understanding of the functional basis of fungal pathogenicity.

Project description:BACKGROUND: The basidiomycete fungus Moniliophthora perniciosa is the causal agent of Witches' Broom Disease (WBD) in cacao (Theobroma cacao). It is a hemibiotrophic pathogen that colonizes the apoplast of cacao's meristematic tissues as a biotrophic pathogen, switching to a saprotrophic lifestyle during later stages of infection. M. perniciosa, together with the related species M. roreri, are pathogens of aerial parts of the plant, an uncommon characteristic in the order Agaricales. A genome survey (1.9x coverage) of M. perniciosa was analyzed to evaluate the overall gene content of this phytopathogen. RESULTS: Genes encoding proteins involved in retrotransposition, reactive oxygen species (ROS) resistance, drug efflux transport and cell wall degradation were identified. The great number of genes encoding cytochrome P450 monooxygenases (1.15% of gene models) indicates that M. perniciosa has a great potential for detoxification, production of toxins and hormones; which may confer a high adaptive ability to the fungus. We have also discovered new genes encoding putative secreted polypeptides rich in cysteine, as well as genes related to methylotrophy and plant hormone biosynthesis (gibberellin and auxin). Analysis of gene families indicated that M. perniciosa have similar amounts of carboxylesterases and repertoires of plant cell wall degrading enzymes as other hemibiotrophic fungi. In addition, an approach for normalization of gene family data using incomplete genome data was developed and applied in M. perniciosa genome survey. CONCLUSION: This genome survey gives an overview of the M. perniciosa genome, and reveals that a significant portion is involved in stress adaptation and plant necrosis, two necessary characteristics for a hemibiotrophic fungus to fulfill its infection cycle. Our analysis provides new evidence revealing potential adaptive traits that may play major roles in the mechanisms of pathogenicity in the M. perniciosa/cacao pathosystem.

Dataset Information

Early development of Moniliophthora perniciosa basidiomata and developmentally regulated genes.

Publications

Early development of Moniliophthora perniciosa basidiomata and developmentally regulated genes.

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