MONOPHYLY OF THE CONIFER SPECIES IN THE CERATOCYSTIS-COERULESCENS COMPLEX BASED ON DNA-SEQUENCE DATA

Ceratocystis sensu stricto includes numerous species of insect-vectore d, wood-staining and plant pathogenic fungi. Among these, Ceratocystis coerulescens is a well-known cause of blue-stain in spruce and pine. Previous investigations, using morphological characteristics and isozy me comparisons, have shown that C. coerulescens encompasses at least f ive morphological types. The aim of this study was thus to compare iso lates of C. coerulescens sensu late and morphologically similar specie s, including C. laricicola, C. polonica, C. virescens, C. eucalypti, C halara australis and Ch. neocaledoniae, on the basis of DNA sequence d ata. Using the polymerase chain reaction (PCR), a 600 base pair fragme nt within the ribosomal DNA operon was amplified, and the PCR products were sequenced. The analyzed sequence included the 5.8S rRNA gene and the internal transcribed spacers (ITS) 1 and 2. Relationships were de termined by parsimony analysis. Using C. fimbriata as the outgroup tax on, the five morphological types previously known as C. coerulescens a nd the two other taxa from conifers formed a strongly-supported monoph yletic group that includes all the Ceratocystis species occurring prim arily on conifers. The species from hardwood trees, C. eucalypti, Ch. australis and Ch. neocaledoniae, also formed a monophyletic group, sis ter to the conifer group. The fourth species from hardwoods, C. viresc ens, formed a group basal to the two sister groups.