The role of microtubules in establishing cell polarity and in polar growth of the phytopathogenic fungus Ustilago maydis

• Applicant: Professor Dr. Gero Steinberg
• Subject Area: Cell Biology
• Term: from 2001 to 2005
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5332016

During growth of haploid cells of the dimorphic plant pathogen Ustilago maydis the new bud is formed at the cell pole of the elongated cell. The initiation of this process is accompanied by the polarization of the microtubule cytoskeleton and the appearance of two microtubule organizing centers (MTOCs) at the growth region. These MTOCs contain g-tubulin and appear to focus the "minus"-ends of the microtubules towards the growing bud, suggesting that microtubule dependent transport supports polar budding. Recently, rapid transport of endosomes along microtubules was shown to support polar growth of haploid cells as well as dikaryotic hypha, and it is thought that endosomes are involved in directed delivery of wall components to the tip of the cell. Moreover, studies on conditional tubulin mutants of U. maydis have shown that microtubules not only affected morphogenesis and polar growth but are of central importance for the spatial determination of the polar growth site. This argues for a role of microtubules in (1) determination the cell poles and (2.) in the directed membrane traffic towards the polar growth region. It is the aim of this project to analyze both aspects of microtubule function in greater detail. By using molecular genetics in combination with cytology we will try to identify regulatory or structural components that participate in the polarization of the microtubule cytoskeleton prior to polar bud formation.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1111: Cell Polarity