The ham-5, rcm-1 and rco-1 genes regulate hyphal fusion in Neurospora crassa

Abstract

Mutants ofNeurospora crassaunable to participate in vegetative hyphal fusion (anastomosis) were isolated and characterized. From this analysis, three genes,rcm-1,rco-1andham-5, were identified and shown to be required for hyphal fusion. Thercm-1andrco-1genes are homologues of theSaccharomyces cerevisiae SSN6andTUP1genes, which encode a dimeric transcription factor in yeast. We demonstrate that inN. crassathercm-1andrco-1genes are required for hyphal fusion and normal hyphal morphology, and influence both asexual and sexual development. Theham-5gene encodes a 1686 amino acid protein with two putative WD40 domains, which might participate in protein–protein interactions.ham-5deletion mutants had a reduced rate of hyphal extension and altered hyphal morphology, and were unable to produce the conidial anastomosis tubes that are required for hyphal fusion during colony initiation.