Mannosyltransferase is required for cell wall biosynthesis, morphology and control of asexual development in Neurospora crassa

Abstract

Two Neurospora mutants with a phenotype that includes a tight colonial growth pattern, an inability to form conidia and an inability to form pro-toperithecia have been isolated and characterized. The relevant mutations were mapped to the same locus on the sequenced Neurospora genome. The mutations responsible for the mutant phenotype then were identified by examining likely candidate genes from the mutant genomes at the mapped locus with PCR amplification and a sequencing assay. The results demonstrate that a map and sequence strategy is a feasible way to identify mutant genes in Neurospora. The gene responsible for the phenotype is a putative alpha-1,2-mannosyltransferase gene. The mutant cell wall has an altered composition demonstrating that the gene functions in cell wall biosynthesis. The results demonstrate that the mnt-1 gene is required for normal cell wall biosynthesis, morphology and for the regulation of asexual development.

• conidiation
• fungal cell wall biosynthesis
• galactomannan
• protein glycosylation
• protoperithecia

We thank Dr Gregory O. Kothe for the isolation of the T-6 mutant. This work was financed by donations to the UB Foundation. Additional support was provided by the Department of Energy-financed (DE-FG02-93ER-20097) Center for Plant and Microbial Complex Carbohydrates.