Isolation and characterization of Aspergillus nidulans delayed conidiation mutants.

Jenny Wieser, and Thomas H. Adams.


The formation of conidiophores in A. nidulans is a precisely regulated event that occurs within the context of a radially expanding colony. Conidiophores typically differentiate 1-2 mm behind the leading edge of vegetatively growing hyphae. We have previously characterized four A. nidulans genes flbB, flbC, flbD, and flbE that result in fluffy colonies that are delayed at least 24 hours in their ability to form conidiophores. This delay in conidiophore initiation gives rise to colonies in which conidiophore development occurs 12-15 mm behind the leading edge of the radially growing hyphae, flbB, flbC, flbD, and flbE were four of the six fluffy low brIA (FLB) expression mutants isolated in our original screen that identified 122 fluffy mutants with altered levels of brIA expression. In this screen, the delayed conidiation mutants were the most abundantly isolated phenotype indicating that proper timing of conidiophore development with in the context of a growing colony is a complex process that requires the combined activities of many genes. Twenty-nine delayed conidiation mutants that express higher levels of brIA fluffy medium brIA (FMB) and fluffy high brIA (FHB) but otherwise are phenotypically identical to flbB, flbC, flbD, and flbE were isolated. These FMB and FHB delayed conidiation mutants represent at least 4 new alleles and multiple alleles of three of the genes were isolated. Sequence analysis of three of these new delayed conidiation mutants is in progress and their genetic interactions with the previously characterized fluffy mutants flbA, fluG, flbB, flbC, flbD, and flbE will be presented.

abstract No: 

Fungal Genet. Newsl. 46 (Supl):

Full conference title: 

Fungal Genetics Conference 20th
    • Fungal Genetics Conference 20th (1999)