Rodletless, a new Aspergillus developmental mutant induced by directed gene inactivation

Abstract

The Aspergillus nidulans CAN41 transcription unit is activated by the brlA regulatory gene early during development of the asexual reproductive apparatus, the conidiophore. Disruption of CAN41 results in a novel mutant phenotype in which conidiophore cells and spores lack an external wall layer, the rodlet layer, making them less hydrophobic than in the wild type and leading to inefficient spore dispersal. The rodletless mutation defines a new locus on chromosome III, rodA. rodA encodes a small, moderately hydrophobic polypeptide containing 8 cysteines arranged in a pattern similar to that observed in three hydrophobic cell wall proteins from the Holobasidiomycete Schizophyllum commune. We propose that the Aspergillus and Schizophyllum 8-cysteine polypeptides define a class of secreted, hydrophobic, fungal cell wall proteins that are important in the formation and function of aerial structures such as conidiophores and mushrooms.