Barcoding of entomopathogenic fungi from olive tree pests : prospects and limitations

Abstract

From all the barcoding initiatives in progress, fungal barcode is probably the one where more difficulties have been encountered. While for plants and animais the barcode regions were easy to define, for fungi the choice was not so straightforward. The internal transcribed spacer (ITS) region was one of the proposed DNA regions for barcoding fungi. This is an extensively used region, for molecular systematic and identification of species, being probably the most widely sequenced DNA region of fungi. This is due to the simplicity of the amplification, related to the multicopy nature of the rDNA; the possibility of using universal primers; and the high levei of sequence variation that occurs even between closely related species. Furthermore, a significant number of identified sequences for comparison are available in the GenBank database. Although the ITS region of rDNA was chosen for some groups of fungi, the use of this region presents very limited application for others, especially for Ascomycetes. As some of the most important entomopathogenic fungi are Ascomycetes, belonging to genera Beauveria, Cordyceps, Isaria, Lecanicillium and Paecilomyces, the use of the ITS region for barcoding purpose are being complemented with other regions. This work, based on the identification of fungal entomopathogens isolated directly from cadavers of one of the major pests in olive graves, the olive moth iPrevs oleae Bern.), intends to illustrate the application of the ITS region to identify these fungal species. The use of this region proved to be useful for the identification of most of the entomopathogenic fungi found in dead larvae and pupae of P. oleae. However, the use ot ITS region for barcode purposes did not allow the identification of several isolates, proving the requiremerít of using a second barcoding region, to enable full fungal identification.