Related Experiment Video
Updated: Jun 18, 2026

Using Ustilago maydis as a Trojan Horse for In Situ Delivery of Maize Proteins
Published on: February 8, 2019
The Ustilago maydis b mating type locus controls hyphal proliferation and expression of secreted virulence factors in
Ramon Wahl1, Alexander Zahiri, Jörg Kämper
1Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, D-76187 Karlsruhe, Germany.
Abstract:
Sexual development in fungi is controlled by mating type loci that prevent self-fertilization. In the phytopathogenic fungus Ustilago maydis, the b mating type locus encodes two homeodomain proteins, termed bE and bW. After cell fusion, a heterodimeric bE/bW complex is formed if the proteins are derived from different alleles. The bE/bW complex is required and sufficient to initiate pathogenic development and sexual reproduction; for the stages of pathogenic development succeeding plant penetration, however, its role was unclear. To analyse b function during in planta development, we generated a temperature-sensitive bE(ts) protein by exchange of a single amino acid. bE(ts) strains are stalled in pathogenic development at restrictive temperature in planta, and hyphae develop enlarged, bulbous cells at their tips that contain multiple nuclei, indicating a severe defect in the control and synchronization of cell cycle and cytokinesis. DNA array analysis of bE(ts) mutant strains in planta revealed a b-dependent regulation of genes encoding secreted proteins that were shown to influence fungal virulence. Our data demonstrate that in U. maydis the b heterodimer is not only essential to establish the heterodikaryon after mating of two compatible sporidia and to initiate fungal pathogenicity, but also to sustain in planta proliferation and ensure sexual reproduction.
More Related Videos
Related Concept Videos
Yeast Signaling
Regulation of Bacterial Virulence
Fungal Group Zygomycota
Gene Regulation in Microbial Communities: Quorum Sensing
Gene Regulation During Sporulation
Microbe-Plant Interactions

