Submitted to: BMC Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2008
Publication Date: 11/18/2008
Citation: Mondego, J.M., Carazolle, M.F., Costa, G., Formighieri, L.P., Parizzi, L.P., Rincones, J., Cotomacci, C., Vidal, R.O., Estrela, R.C., Garcia, O., Castro, L.A., Gramacho, K.P., Goncalves, M.S., Neto-Goes, A., Barbosa, L.V., Guiltinan, M.J., Bailey, B.A., Meinhardt, L.W., Cascardo, J.C., Pereira, G.A. 2008. A genome survey of Moniliophthora perniciosa gives new insights into Witches’ Broom Disease of cacao. Biomed Central (BMC) Genomics. 9:548.
Interpretive Summary: Research into diseases of cacao is important to the U.S. economy because cacao is the raw material for the production of chocolate and the chocolate industry is one of the main consumers of U.S. grown dairy, nuts, oils, and sugar products. Fungal diseases such as Witches’ Broom Disease (WBD) of cacao have devastated cacao production in much of the Western Hemisphere. WBD is caused by the fungus Moniliophthora perniciosa. In the present study we analyzed the DNa and genes of the fungus. The results showed that the fungus has genes that make it highly adaptive to the tropical environment, with multiple mechanisms that modify the plants and lead to the disease. This information provides insight into how this fungus functions and provides researchers mechanisms to develop new control measures. Plant pathologists, biologists, and mycologists will benefit directly from this information.
Technical Abstract: 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 the 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 oxidative stress (ROS) resistance, drug efflux transport and cell wall degradation were identified. An expansion of the P450 family (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). 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.