Molecular biological analysis of cell adhesion in Ashbya gossypii Ashbya gossypii is a filamentous fungus of the family Saccharomycetaceae and about 95% of its genes have a homologue in the yeast Saccharomyces cerevisiae. S. cerevisiae can turn into a filamentous growth form for which the expression of adhesion molecules is necessary. Some of these so called FLO genes have homologues in A. gossypii which are AgFLO5 1 and AgFLO5 2 AgFLO11 and AgFIG2. Genes encoding the transcriptional regulators AgFlo8 AgSfl1 as well as AgTec1 and AgSte12 are present as well. Unlike in S. cerevisiae flocculation gene products in A. gossypii do not bind to mannose. Deletion of A. gossypii adhesins and most of their transcriptional regulators did not alter the colony phenotype. However Agflo8 Agsfl1 and Agtec1 showed a growth delay. Formation of aerial hyphal aggregations and the attachment to the growth substrate was not impaired. The mentioned mutants sporulated in an abundant manner compared to the precursor strain but spore phenotypes were normal. Reporter gene assays and promoter analysis revealed that AgFlo8 induces the expression of AgSFL1 which in turn represses AgFLO5 2 AgFLO8 and AgFIG2. The AgFLO8 and AgSFL1 deletion mutants seemed to possess certain insensitivity to elevated sugar levels indicating non sufficient stress response in the absence of AgSfl1. Overexpression of AgSFL1 resulted in a wild type like phenotype.