Abstract

To search for the dematiaceous fungi in nature, clarify their habitat and the environmental circumstances in which they may infect man, we studied the phylogenetic relationships of these isolates. 60 dematiaceous fungal strains out of 367 soil samples were isolated. They were further identified by molecular biological method. The phylogenetic relationships were demonstrated by using internal transcribed spacer (ITS) region of ribosomal DNA sequences. In the neighbor-joining (NJ) tree, Phialophora sp.,Cladophialophora chaetospira, Exophiala spinifera, Phaeococcomyces sp. and Exophiala eucalyptorum formed cluster A, Didymella bryoniae, Leptosphaeriaceae sp., Ascomycetesp., Microdiplodia hawaiiensis and Cochliobolus lunatus formed cluster B, Staninwardia suttonii, Cladosporium oxysporum, Cladosporium cladosporioides, Cladosporium sp. andMelanized limestone ascomycete formed cluster C, and Scolecobasidium tereum,Scolecobasidium humicola formed cluster D. The phylogenetic relationships between cluster B, cluster C and cluster D were closer than that of cluster A. Dematiaceous species were found widely in Guangdong soil, and the distribution amounts were not in a specific pattern, the phylogenetic method based on the rDNA ITS sequence was proven to be a quick and accurate fungi identify method. There is a relationship between genetic distances and some biological habits of some strains, but lacking of connection was found between the genetic distances and the geographical factors.

Key words: Dematiaceous fungi, isolation, phylogenetic tree, internal transcribed spacer (ITS) region, ribosomal DNA (rDNA).