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Title: Variability of the mitochondrial SSU rDNA of entomopathogenic fungi

item Humber, Richard
item HODGE, K.
item BINNECK, E.

Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2008
Publication Date: 10/1/2008
Citation: Sosa-Gomez, D.R., Humber, R.A., Hodge, K.T., Binneck, E., Da Silva-Brandao, K.L. 2008. Variability of the mitochondrial SSU rDNA of entomopathogenic fungi. Mycopathologia. 167:145-154.

Interpretive Summary: This manuscript reports the utility of the sequences of mitochondrial short subunit rDNA (SSU mt-rDNA) gene to assess evolutionary and taxonomic issues among fungi that are pathogens of insects. The group of fungi used is the most diverse and most important cluster of insect fungi actually used as biocontrol agents against insects. Particular emphasis was on a globally diverse set of isolates of Nomuraea rileyi, one of the major pathogens killing agricultural significant moths. The results confirm that N. rileyi shows very little genomic variability throughout the world and should be regarded as a single globally distributed species rather than as a complex of morphologically similar but genetically distinct species. This study confirms that the mitochondrial gene sequence of interest here can be added to the group of genes that can be useful indicators of relatedness or for taxonomic identification purposes.

Technical Abstract: Hypocrealean arthropod pathogenic fungi have profound impact on the regulation of agricultural and medical pests. However, until now the genetic and phylogenetic relationships among species have not been clarified, such studies could clarify host specificity relationships and define species boundaries. Our purpose was to compare the sequences of the mitochondrial SSU rDNA fragments from several mitosporic entomopathogenic Hypocreales to infer relationships among them and to evaluate the possibility to use these sequences as species diagnostic tool in addition to the more commonly studied sequences of nuclear SSU rDNA. The SSU mt rDNA proved to be useful to help in differentiation of species inside several genera. Clusters obtained with Parsimony, Bayesian and Maximum Likelihood analyses were congruent with a new classification of the Clavicipitaceae (Sung et al., Studies in Mycology 57: 5-59, 2007) in which the anamorphic genera Nomuraea and Metarhizium species remain in the Clavicipitaceae and Isaria species sequenced here are assigned to family Cordycipitaceae. Mitochondrial genomic information indicates the same general pattern of relationships demonstrated by nuclear gene sequences.