Location: Sustainable Perennial Crops LaboratoryTitle: Genes acquired by horizontal transfer are potentially involved in the evolution of phytopathogenicity in Moniliophthora perniciosa and Moniliophthora roreri, two of the major pathogens of cacao) Author
Submitted to: Journal of Molecular Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2009
Publication Date: 12/23/2009
Citation: Tiburcio, R.A., Costa, G.G., Carazzolle, M.F., Schuster, S.C., Carlson, J.E., Guiltinan, M.J., Bailey, B.A., Argueso, J.L., Mieckowski, P., Meinhardt, L.W., Pereira, G.A. 2009. Genes acquired by horizontal transfer are potentially involved in the evolution of phytopathogenicity in Moniliophthora perniciosa and Moniliophthora roreri, two of the major pathogens of cacao. Journal of Molecular Evolution. 70:85-97. Interpretive Summary: Moniliophthora perniciosa and Moniliophthora roreri are plant pathogens of the same family that cause two of the most devastating fungal diseases of Theobroma cacao, the source of chocolate. In the broader fungal group that these two pathogens belong to, the ability to cause plant diseases is rare. In this paper we attempt to explain how this small fungal family acquired the ability to cause plant diseases. The capacity to cause disease appears to have been obtained by a common ancestor of these two fungi when functional genes from other nonrelated organisms were somehow included into their genomes. 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 perniciosa and Moniliophthora roreri are phytopathogenic basidiomycete species that infect cacao and cause the two main diseases in this crop: “Witches’ Broom” and “Frosty Pod”, respectively. The ability of species from this genus (Moniliophthora) to cause disease is exceptional in the family Marasmiaceae because species in closely related genera including, Marasmius, Crinipellis, and Chaetocalathus, are mainly saprotrophs and are not known to cause disease. In this work, the possibility that this phytopathogenic lifestyle has been acquired by horizontal gene transfer (HGT) was investigated using a stringent genome comparison pipeline to identify potential genes that have been obtained by Moniliophthora through HGT. This search led to the identification of three genes: a metallo-dependent hydrolase (MDH), a mannitol phosphate dehydrogenase (MPDH) and a family of necrosis inducing proteins (NEPs). Phylogenetic analysis of these genes suggests that Moniliophthora acquired NEPs from oomycetes, MDH from actinobacteria and MPDH from firmicutes. Based on the known gene functions and on previous studies of M. perniciosa infection and development, a correlation between gene acquisition and the evolution of the phytopathogenic genus Moniliophthora can be postulated.