Cloning and characterization of a gene coding for a class I chitin synthase from Fusarium graminearum

The full-length sequence of a gene coding for a class I chitin synthase (Chs) from Fusarium graminearum (Fg) was isolated by genome walking, using gene-specific primers and walking libraries constructed with a panel of eight restriction enzymes. Analysis of the gene (named FgChs1) and its corresponding cDNA revealed an open reading frame of 2703 bp interrupted by two introns of 120 and 55 bp, respectively. FgChs1 is a single-copy gene. Its deduced amino acid sequence shows 77% identity to Neurospora crassa Chs3 and 73% identity to Ophiostoma novo-ulmi ChsA in the conserved central region (residues 153 to 800). Quantitative reverse transcription - polymerase chain reaction was used to compare the levels of FgChs1 mRNA at different stages of development. This showed that FgChs1 was developmentally regulated, with peaks of expression during spore germination and mycelial growth. The first significant increase in FgChs1 mRNA levels was detected after 1 day of hyphal growth while the second peak was apparent after 5 days. This result suggests that FgChs1 may play an important role in fungal growth and development.