title: Fungal dimorphism regulated gene expression in Ustilago maydis: I. Filament up-regulated genes.
abstract: SUMMARY Ustilago maydis displays dimorphic growth alternating between a budding haploid and a filamentous dikaryon formed by mating of two haploid cells. This morphological switch plays a critical role in pathogenicity because only the filamentous dikaryon can infect maize. Previously we identified a role for the cAMP signalling pathway in dimorphism and pathogenicity. In the present work we used suppression subtractive hybridization to identify genes up-regulated in filamentous cells in our search for new genes involved in morphogenesis. Differential expression was verified by Northern blot analysis. We isolated and sequenced full-length genomic cosmid clones of two of these genes and produced disruption/deletion mutants to examine their roles in morphogenesis and pathogenicity. One of these genes encodes a putative member of the aldo-keto reductase family and is designated uor1. The other (ufu57) does not have significant similarity with any sequence previously reported. Partial deletion mutants of these two sequences have no apparent effect on morphogenesis, mating or pathogenicity.
authors.affiliation: Department of Plant Pathology, University of Georgia, Athens, GA 30602-7274, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Andrews
authors.forename: María D
authors.initials: MD
authors.lastname: García-Pedrajas
authors.forename: Scott E
authors.initials: SE
authors.lastname: Gold