Morphological and molecular characterization of an entomopathogenic fungus, Cordyceps farinosa and phylogenetic analysis of the genus based on the ITS-rDNA and ß-tubulin sequences

Abstract

An isolate of entomopathogenic fungus was isolated from the soil samples by using the Galleria bait method. Species identification was carried out using morphology and phylogenetic analysis of ITS-rDNA region and ß-tubulin gene sequences by Maximum parsimony (MP) method. Based on the both morphological and molecular characterization, the isolate KJ3 was identified as Cordyceps farinosa. The isolates showed an ellipsoidal conidial shape with overall dimensions of 3.83 × 1.98 µm (length ×width). The phialide of the isolate was characterized by a wide globose basal portion and overall dimensions of 4.98 × 2.21 µm. The PCR-amplified ITS and ß-tubulin regions were 615and 355 bp, respectively. In all constructed phylogenetic trees, C. farinosa isolate KJ3 grouped together with C. farinosa CBS 541.81 as a monophyletic group. Based on the ITS-rDNA sequence, in reconstructed phylogenetic tree, a group including C. albocitrina and C. coccidioperitheciata appeared as sister group of C. farinose. Cordyceps confrogasa was the genealogically closest species to I. farinosa based on the ß-Tubulin sequence. With the aim of comparing the efficiencies of ITS-rDNA and ß-Tubulin sequences for Cordyceps spp. genealogic studies, MP phylogenetic trees with the similar sets of species were reconstructed based on the both genomic regions in combination and alone and then compared in terms of consistency index, retention index and topology. The results showed that phylogenetic analysis based on the ß-Tubulin sequence is more efficient way for genealogical studies in Cordyceps spp..

Keywords

• ß-tubulin
• great wax moth
• its-rdna
• phylogenetic tree