Submitted to: Molecular Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/3/2008
Publication Date: 7/1/2008
Citation: Rincones, J., Scarpari, L.M., Mondego, J.M., Carazzolle, M.F., Formighieri, E.F., Costa, G.G., Barau, J.G., Vilas-Boas, L.A., Sabha, M., Azevedo, R.A., Dias, R., Cascardo, J.M., Meinhardt, L.W., Periera, G.A. 2008. Differential gene expression between the biotrophic-like and saprotrophic mycelia of the Witches’ broom pathogen Moniliophthora perniciosa. Molecular Microbiology. 21:891-908. Interpretive Summary: Research into diseases of cacao is important to the USA economy because cacao is the raw material for the production of chocolate and the chocolate industry is one of the main consumers of US 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 gene expression from different stages of M. perniciosa, which is the first expression analysis for this fungus. The results showed that the different life stages have diverse metabolic patterns. 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: Moniliophthora perniciosa is a hemibiotrophic fungus that causes Witches’ Broom disease in cacao. Marked dimorphism characterizes the biotrophic phase, which actually causes the disease symptoms, and the saprotrophic phase. A combined strategy of DNA microarray, EST and real-time PCR analyses was employed to analyze differences between the two fungal stages. DNA microarrays were performed for 2,304 putative genes and hybridized with cDNA from different phases, resulting in the identification of 195 differentially expressed genes. 4595 valid reads were clusterized producing 1534 unigenes (522 clusters and 1012 singlets). From the contigs, 85 were biotrophic specific, 387 saprotrophic specific and 100 were from both. 766 (50%) unigenes matched annotated sequences in public databases. Results were independently confirmed via real-time RT-PCR for selected genes. Our results indicate marked metabolic differences between these two life stages, with glycolysis and the malate shunt being repressed in the biotrophic mycelium. The biotrophic phase also appears to be under amino acid starvation and expresses several potential pathogenicity factors, such as glyoxal oxidase, ceratoplatanin and proteases. This work significantly contributes to our understanding the molecular mechanisms of WBD and to our knowledge, is the first to analyze differential gene expression of the different phases of a hemibiotrophic fungal pathogen.