A genome survey of Moniliophthora perniciosa gives new insights into Witches' Broom Disease of cacao

Abstract

BackgroundThe 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 (1.9× coverage) of M. perniciosa was analyzed to evaluate the overall gene content of this phytopathogen.ResultsGenes 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.ConclusionThis 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.

Genome expansion and lineage-specific genetic innovations in the forest pathogenic fungi Armillaria

“…The most highly upregulated genes included expansins (log 2 FC VM = 10.44), bZip and C 2 H 2 transcription factors, three caspase genes, hydrophobins, cytochrome p450s, GHs as well as several unannotated genes. We found an overexpression of 5-oxoprolinases downstream factors of neutralizing intracellular H 2 O 2 and signs of intensified biogenesis and cargo of extracellular proteins (Supplementary Figs 13,14). A moderate set of PCWDE genes was expressed in rhizomorphs, suggestive of assimilative or invasive properties, although the highest PCWDE suite was observed in vegetative mycelium .…”

“…Despite their huge impact on forestry, horticulture and agriculture, the genetics of the pathogenicity of Armillaria species is poorly understood. The only -omics data published so far have highlighted a substantial repertoire of plant cell wall degrading enzymes (PCWDE) and secreted proteins, among others, in A. mellea and A. solidipes 11,12 , while analyses of the genomes of other pathogenic basidiomycetes (such as Moniliophthora 13,14 , Heterobasidion 15 and Rhizoctonia 16 ) identified genes coding for PCWDEs, secreted and effector proteins or secondary metabolism (SM) as putative pathogenicity factors. However, the lifecycle and unique dispersal strategy of Armillaria prefigure other evolutionary routes to pathogenicity, which, along with other potential genomic factors (such as transposable elements 17 ) are not yet known.…”

Trypsin-specific inhibitors from the basidiomycete Clitocybe nebularis with regulatory and defensive functions

“…High sequence similarity was also found for limited regions of one other predicted protein in the C. cinerea genome and another four from the genome of L. bicolor. Similarly, sequence identity (35 %) was also found with the Cterminal half of a protein with a partial sequence annotated in the Moniliophthora perniciosa FA553 genome (Mondego et al, 2008). In contrast to LeSPI and other putative serine protease inhibitors that do not have cysteines, cnispin contains a single cysteine in its amino acid sequence (C36).…”

The distribution of a transposase sequence in Moniliophthora perniciosa confirms the occurrence of two genotypes in Bahia, Brazil

“…Rincones et al (2003Rincones et al ( , 2006 showed genotypic polymorphisms among different biotypes and among C-biotype isolates from different regions of southern Bahia by electrophoretic karyotype and microsatellite analysis. Furthermore, it has been postulated that the genome variability found in homothallic M. perniciosa may be due to transposable elements (TEs) and ectopic recombination guided by the numerous copies of these elements found in the genome (Rincones et al, 2003;Mondego et al, 2008).…”

“…The sequences generated by this project were submitted to a local database with restricted access. Searches in this database show that the pathogen has several sequences related to TEs already ascribed to filamentous fungi (for a review, see Mondego et al, 2008).…”