Sequence analysis of the chitin synthase A gene of the Dutch elm pathogen Ophiostoma novo-ulmi indicates a close association with the human pathogen Sporothrix schenckii

Degenerate oligonucleotide primers were designed according to conserved reg ions of the chitin synthase gene family and used to amplify a 621 basepair (bp) fragment from genomic DNA of Ophiostoma novo-ulmi, the causal agent of Dutch elm disease. The amplification product was used as a hybridization p robe to screen a library of genomic DNA sequences and to retrieve a full-le ngth chitin synthase gene (chsA). The putative coding region of the gene wa s 2619 bp long, lacked introns, and encoded a polypeptide of 873 amino acid s. Based on the similarity of the predicted amino acid sequence to the full -length chsC gene of Aspergillus nidulans and chsA gene of Ampelomyces quis qualis, the O. novo-ulmi chsA was classified as a Class I chitin synthase. The phylogenies constructed, according to a subregion of all available chit in synthases, showed that O. novo-ulmi consistently clustered most closely with the human pathogen Sporothrix schenckii, recently classified as a memb er of the mitosporic Ophiostomataceae. Disruption of the chsA gene locus ha d no obvious effects on the growth or morphology of the fungus. (C) 1999 El sevier Science B.V. All rights reserved.