134 -- Overexpression of the Neurospora crassa Transcription Factor fsd-1 Inhibits Mating

The filamentous fungus Neurospora crassa can undergo both asexual and sexual reproduction. However, little is known about the molecular mechanisms that regulate the N. crassa sexual development cycle. Previous research has shown that deletion strains of the transcription factor fsd-1 have delayed development of female reproductive structures and are sterile. fsd-1 is transcribed into three different transcripts, which differ by the length and intron/exon structure of their 5’ untranslated region, and these transcripts vary in expression level during the life cycle. The goal of this project is to phenotypically characterize the reproductive ability of strains overexpressing fsd-1, for each of the three transcripts, and we hypothesize that fsd-1 overexpression will affect the reproductive ability of these strains. Analysis of the reproductive abilities of fsd-1 overexpression strains showed that these strains can produce spores, but that spores do not germinate. Specifically, overexpression of fsd-1 transcript 1 and 2 resulted in no ascospores produced, while transcript 3 strains did shoot ascospores. However, we could not recover ascospores with the overexpression genotype for any of the strains overexpressing fsd-1. In addition, characterization of the changes in transcriptional expression caused by fsd-1 overexpression will give us insight into the fsd-1 regulon. Using Illumina RNA sequencing, we mapped the genome-wide transcriptional changes that occur as a result of fsd-1 overexpression. Our RNAseq and phenotype experiments revealed that fsd-1 regulates processes including melanin synthesis, cell wall formation, and ascospore viability, and plays a key role in sexual development.