The Ustilago maydis Cys2His2-type zinc finger transcription factor Mzr1 regulates fungal gene expression during the biotrophic growth stage.
The smut fungus Ustilago maydis establishes a biotrophic relationship with its host plant maize to progress through sexual development. Here, we report the identification and characterization of the Cys(2)His(2)-type zinc finger protein Mzr1 that functions as a transcriptional activator during host colonization. Expression of the U. maydis mig2 cluster genes is tightly linked to this phase. Upon conditional overexpression, Mzr1 confers induction of a subset of mig2 genes during vegetative growth and this requires the same promoter elements that confer inducible expression in planta. Furthermore, expression of the mig2-4 and mig2-5 genes during biotrophic growth is strongly reduced in cells deleted in mzr1. DNA-array analysis led to the identification of additional Mzr1-induced genes. Some of these genes show a mig2-like plant-specific expression pattern and Mzr1 is responsible for their high-level expression during pathogenesis. Mzr1 function requires the b-dependently regulated Cys(2)His(2)-type cell cycle regulator Biz1, indicating that two stage-specific regulators mediate gene expression during host colonization. In spite of a role as transcriptional activator during biotrophic growth, mzr1 is not essential for pathogenesis; however, conditional overexpression interfered with proliferation during vegetative growth and mating ability, caused a cell separation defect, and triggered filamentous growth. We discuss the implications of these findings.
Zheng
Yan
Y
Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
Kief
Jan
J
Auffarth
Kathrin
K
Farfsing
Jan W
JW
Mahlert
Michael
M
Nieto
Fernanda
F
Basse
Christoph W
CW
D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal; D016366:Open Reading Frames; D010935:Plant Diseases / Q000382:microbiology; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014588:Ustilago / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D003313:Zea mays / Q000382:microbiology*; D016335:Zinc Fingers
D005656:Fungal Proteins; D014157:Transcription Factors