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Title: MALDI-TOF MS of Trichoderma: A model system for the identification of microfungi

item DE RESPINIS, SOPHIE - Cantonal Institute Of Microbiology Icm
item VOGEL, GUIDO - Mabritec
item BENAGLI, CINZIA - Cantonal Institute Of Microbiology Icm
item TONOLLA, MAURO - Cantonal Institute Of Microbiology Icm
item PETRINI, ORLANDO - Cantonal Institute Of Microbiology Icm
item Samuels, Gary

Submitted to: Mycological Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2009
Publication Date: 3/17/2010
Citation: De Respinis, S., Vogel, G., Benagli, C., Tonolla, M., Petrini, O., Samuels, G.J. 2010. MALDI-TOF MS of Trichoderma: A model system for the identification of microfungi. Mycological Progress. 9(1):79-100

Interpretive Summary: Fungi in the mould genus Trichoderma are used to control plant diseases; however these fungi are difficult to identify. Only very small differences in their microscopic structures indicate what they are. This paper examines the potential of using other kinds of techniques to identify species of Trichoderma. By analysis of a particular kind of small molecules called peptides it was possible to identify species using a machine called a mass spectrometer that can detect differences in the peptides. This method gives results similar to DNA sequencing but provides the results more rapidly. It also provides information that is useful in developing classification systems for Trichoderma and, potentially, can be applied to other groups of mould fungi. Plant pathologists working to develop these fungi to control plant diseases will use this research.

Technical Abstract: This investigation aimed to assess whether MALDI-TOF MS analysis of proteomics could be applied to the study of Trichoderma, a fungal genus selected because it includes many species and is phylogenetically well defined. We also investigated whether MALDI-TOF MS analysis of proteomics would reveal apomorphies that could be useful in separating species in this genus. One hundred and twenty nine morphologically and genetically well characterized strains of Hypocrea and Trichoderma, belonging to 24 species in 8 phylogenetic clades were analyzed by MALDI-TOF mass spectrometry. The resulting peak lists of individual samples were submitted to UPGMA cluster analysis to produce a taxonomic tree. SuperSpectra™ for the 13 most relevant species of Trichoderma were computed. The results confirmed previously defined clades and sections. With the exceptions of T. saturnisporum (Longibrachiatum Clade) and T. harzianum (Harzianum Clade) strains of individual species clustered very closely. T. polysporum clustered distantly from all other groups. The MALDI-TOF analysis accurately reflected the phylogenetic classification reported in recent publications and, in most cases, strains identified by DNA sequence analysis clustered together by MALDI-TOF. The resolution of MALDI-TOF was roughly equivalent to ITS rDNA. The MALDI-TOF technique analyzes peptides and represents a rough equivalent to sequencing, making this method a useful adjunct for determining species limits. It also allows simple, reliable and quick species identification, thus representing a valid alternative to gene sequencing for species diagnosis of Trichoderma and other fungal taxa.