THE ASPERGILLUS-NIDULANS GENES CHSA AND CHSD ENCODE CHITIN SYNTHESES WHICH HAVE REDUNDANT FUNCTIONS IN CONIDIA FORMATION

We previously isolated three chitin synthase genes (chsA, chsB, and ch sC) from Aspergillus nidulans. In the present work, we describe the is olation and characterization of another chitin synthase gene, named ch sD, from A, nidulans. Its deduced amino acid sequence shows 56.7% and 55.9% amino acid identity, respectively, with Call of Saccharomyces ce revisiae and Chs3 of Candida albicans. Disruption of chsD caused no de fect in cell growth or morphology during the asexual cycle and caused no decrease in chitin content in hyphae. However, double disruption of chsA and chsD caused a remarkable decrease in the efficiency of conid ia formation, while double disruption of chsC and chsD caused no defec t. Thus it appears that chsA and chsD serve redundant functions in con idia formation.