We describe a strategy for systematic amplification of chitin synthase genes (chs) in the filamentous ascomycetes plant-pathogenBotrytis cinereausing PCR with multiple degen-erate primers designed on specific and conserved sequence motifs. Eight distinctchsgeneswere isolated, namedBcchs I, II, IIIa, IIIb, IV, V, VIandVII. They probably constitute the entire chsmultigenic family of this fungus, as revealed by careful analysis of six euascomycetes I, IIIa,IIIb,IVandVIgenes were subjected to DNA walking and their deduced amino acid sequences were compared by hydrophobic cluster analysis (HCA) to localize putative residues critical for CHS activity. .
