Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/1999
Publication Date: N/A
Interpretive Summary: The genus Mycosphaerella and related anamorphs contain more than 1000 different species of fungi which include many that are pathogens of economically important plants (for example: bananas, barley, carrots, celery, peanuts, soybeans, and wheat). The identification and classification of these fungi have been problematic due to a lack of characters and that in many cases species were determined only on the basi of the host plant. In order to better understand the relationship among these fungi, molecular characters based on DNA sequence analysis was used to study 24 isolates representing 16 different species. These isolates were clustered into 4 groups. As a result of this analysis we propose that the two genera (Pseudocercospora and Paracercospora) be combined into one genera (Pseudocercospora) and that the species Psedocercosporella aestiva be renamed Ramulispora aestiva. This work will be used by other scientists sin their study of these fungi.
Technical Abstract: Partial ribosomal DNA (rDNA) sequences were obtained from twenty-five isolates representing species of Cercospora, Passalora, Paracercospora, Pseudocercospora, Ramulispora, Pseudocercosporella, and Mycocentrospora. The combined Internal Transcribed Spacers (ITS) including the 5.8S rRNA gene (5.8S) and 5' end of the 25S gene (primer pairs F63/R635) on rDNA were eamplified using PCR and directly sequenced. The ITS regions including the 5.8S varied in length from 502 to 595 bp. The F63/R635 region varied from 508 to 519 bp among isolates sequenced. Reconstructed phylogenies inferred from both regions had highly similar topologies for the taxa examined. Phylogenetic analysis of the sequences resulted in three well-supported clades corresponding to Cercospora, Paracercospora/Pseudocercospora, Ramulispora and a Passalora group with bootstrap values larger than 92% for each clade and group. Based on the results of the analysis, a new combination for Pseudocercosporella aestiva is proposed in Ramulispora, an the genus Paracercospora reduced to synonymy under Pseudocercospora.