Molecular Genetics of Conidial Morphogenesis in Neurospora Crassa

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Fungi provide model eukaryotic systems for molecular studies of the cellular processes regulating growth and development. Neurospora crassa and many other fungal species produce asexual spores, called conidia, that are an important means of dispersal. The goal of this research is to define the molecular basis of this simple developmental process. Several genetic loci regulate conidial development in N. crassa and the fluffy gene is the best characterized of these. The predicted fluffy protein has sequence similarity to Gal4-type transcription factors. The primary objective of the work is to characterize the function of fluffy. The fluffy protein has regions suggesting it is a transcription factor. This will be tested. Fluffy's role as a regulator of morphogenesis will be tested by expression of fluffy from a heterologous promoter. The genetic requirements for fluffy-induced gene activation will be determined by examination of conidiation-induced gene expression in developmental mutants. Physiological changes are known to accompany development and the relationship between metabolic state and development has been a topic of interest in N. crassa for over 30 years. The results of the proposed research will provide a deeper understanding of how N. crassa regulates conidiation. Nutrients, light and the circadian clock all contribute to regulation of the timing and abundance of conidia production. Elucidation of the mechanisms that regulate conidiation will provide a foundation for understanding how signal transduction pathways responding to different environmental signals operate together to control cellular differentiation. A second objective of the proposed research is to examine the relationship between physiological changes and development. This project will take advantage of a new technology, transcriptional profiling through analysis of microarrays, to assess the metabolic changes that occur in response to elevated expression of fluffy. Filamentous fungi are a diverse group of organisms with a tremendous impact on society. Fungi play important roles in the decay and recycling of organic material. They are also important pathogens of plants and animals and are used in industrial production of enzymes, chemicals, and pharmaceuticals. A better understanding of the physiology and development of filamentous fungi is important to the goal of manipulating fungi for the purpose of increasing productivity and human health. This project will integrate the molecular events regulating conidiation with physiological events associated with development and responses of fungi to environmental signals.