title: Investigating the Ustilago maydis/Zea mays pathosystem: transcriptional responses and novel functional aspects of a fungal calcineurin regulatory B subunit.
abstract: The sustainable control of basidiomycete biotrophic plant pathogenesis requires an understanding of host responses to infection, as well as the identification and functional analysis of fungal genes involved in disease development. The creation and analysis of a suppressive subtractive hybridization (SSH) cDNA library from Ustilago maydis-infected Zea mays seedlings enabled the identification of fungal and plant genes expressed during disease development, and uncovered new insights into the interactions of this model system. Candidate U. maydis pathogenesis genes were identified by using the current SSH cDNA library analysis, and by knowledge generated from previous cDNA microarray and comparative genomic analyses. These identifications were supported by the independent determination of transcript level changes in different cell-types and during pathogenic development. The basidiomycete specific um01632, the highly in planta expressed um03046 (zig1), and the calcineurin regulatory B subunit (um10226, cnb1), were chosen for deletion experiments. um01632 and zig1 mutants showed no difference in morphology and did not have a statistically significant impact on pathogenesis. cnb1 mutants had a distinct cell division phenotype and reduced virulence in seedling assays. Infections with reciprocal wild-type×Δcnb1 haploid strain crosses revealed that the wild-type allele was unable to fully compensate for the lack of a second cnb1 allele. This haploinsufficiency was undetected in other fungal cnb1 mutational analyses. The reported data improves U. maydis genome annotation and expands on the current understanding of pathogenesis genes in this model basidiomycete.
authors: Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON K9J 7B8, Canada.
authors: Michael E
authors: ME
authors: Donaldson
authors: Shaowu
authors: S
authors: Meng
authors: Alla
authors: A
authors: Gagarinova
authors: Mohan
authors: M
authors: Babu
authors: Scott C
authors: SC
authors: Lambie
authors: Alexander A
authors: AA
authors: Swiadek
authors: Barry J
authors: BJ
authors: Saville
mesh_terms: D019703:Calcineurin / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D054884:Host-Pathogen Interactions; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014588:Ustilago / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence; D003313:Zea mays / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*
chemical_list: D005656:Fungal Proteins; D010940:Plant Proteins; D019703:Calcineurin
keywords: Calcineurin regulatory B subunit; Haploinsufficiency; Suppressive subtractive hybridization cDNA library; Ustilago maydis