Location: Sustainable Perennial Crops LaboratoryTitle: The Mitochondrial Genome of Moniliophthora roreri, the frosty pod rot pathogen of cacao Author
Submitted to: Fungal Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2012
Publication Date: 2/15/2012
Citation: Costa, G.G., Cabrera, O., Tiburico, R.A., Medrano, F., Carazzolle, M., Thomazella, D., Schuster, S., Carlson, J.E., Guiltinan, M.J., Bailey, B.A., Mieckowski, P., Pereira, G.A., Meinhardt, L.W. 2012. The Mitochondrial Genome of Moniliophthora roreri, the frosty pod rot pathogen of cacao. Fungal Biology. 116(5):551-562. Interpretive Summary: Frosty Pod Rot disease (FPR) of cacao, Theobroma cacao, the source of chocolate, affects all cacao growing regions in Central America and most Andean countries of South America. This disease caused by Moniliophthora roreri has significantly reduced cacao yields in all of these growing regions, which affects both U.S industry and consumers. Genome sequences of the complete mitochondrial genome of Moniliophthora roreri was compared to that of M. perniciosa. The comparative analysis showed a high degree of relatedness, with both genomes and revealed a high degree of similarity in gene number, orientation and sequence composition. The main differences are associated with plasmid numbers, their locations and in the number of repetitive sequences within each genome. This information broadens our knowledge of plant disease interactions and will help researchers and plant breeders find and/or develop improved disease resistant crops.
Technical Abstract: Moniliophthora roreri and Moniliophthora perniciosa are closely related basidiomycetes that cause two important diseases in cacao (Theobroma cacao L.): frosty pod rot and the witches' broom disease, respectively. A comparison of the complete mitochondrial genomes of these pathogens shows a high degree of similarity between them, as expected due to their phylogenetic proximity: both genomes are largely syntenic, share the same conserved ORFs and are very similar in GC content, codon usage and tRNAs placement and sequence. Despite these similarities, some relevant differences were found. First, while M. perniciosa mtDNA shows a region previously described as an integrated plasmid, the same region of M roreri shows only traces of an ancient plasmid integration event, but complete polymerases were not detected. Moreover, three free linear plasmids were found in the M. roreri genome, with one being very similar to the integrated plasmid of M. perniciosa. Secondly, M. perniciosa mtDNA has a high number of short repeats located between the conserved genes, while in M. roreri these repeats are much less common. The short repeats are found in a regular pattern along the M. perniciosa mtDNA, except for the region of the integrated plasmid. Lastly, some of the many hypothetical ORFs found in the mitochondrial genome of these pathogens are exclusive to these fungal species. Together, these findings indicate that the mitochondrial genomes of these fungi are very plastic in structure and content, features that could be involved in the evolutionary and functional divergence of these pathogens.