Phylogeny of Cryphonectria cubensis and allied species inferred from DNA analysis

Cryphonectria cubensis causes a serious canker disease of Eucalyptus in many tropical areas of the world. The aim of this study was to determine the phylogenetic relationships among strains of C. cubensis and the related species C. parasitica, Endothia eugeniae and E. gyrosa using DNA sequence data. A second objective was to develop a rapid diagnostic method to distinguish among these taxa. The variable ITS1 and ITS2 regions, as well as the conserved 5.8S gene of the rRNA operon, were amplified and sequenced, The amplified PCR products were also used in Alu I and Cfo I restriction digests. Analysis of the restriction profiles indicate that it is possible to distinguish between C. cubensis, C. parasitica, E. eugeniae and E. gyrosa using RFLPs (restriction fragment length polymorphisms). This will facilitate the identification of isolates thought to represent C. cubensis that sporulate poorly in culture. Analysis of the sequence data showed that C, cubensis isolates form a distinct clade that includes a strain from clove that might otherwise have been assigned the name E. eugeniae, Isolates of C. parasitica formed a separate clade. Endothia gyrosa grouped separately from both C. cubensis and C. parasitica.