We set out to understand how in plant development cells chose a certain fate and how they subsequently differentiate and develop their typical shape. In contrast to what we expected from a text book point of view we found ourselves untangling a complex interplay of various cellular processes including the transcriptional machinery, the cytoskeleton, protein degradation and the cell cycle. Single cell types such as trichomes, hypocotyls cells and root hairs are particuarly well suited to study how these processes contribute to cell fate determination and proper differentiation, using a combination of genetic, molecular and cellular approaches.

The selection of single trichome cells in the epidermis is based on extensive cell-cell interactions. It seems that transcription factors mediate these interactions by direct movement from cell to cell. To analyse these processes, we use an array of both established and novel, sophisticated methods, i.e. the Cre/lox recombination system, Split GFP/Fret, and more conventional biochemical methods.

A second focal point of our interest is establishment and maintenance of cell shape. The so-called Arp2/3 complex is known to initiate new actin branches and is also required for proper cell shape. We are currentyl trying to unravel how the activity of this complex is localized within the cell and how tits localized activity triggers to local growth.

The analysis of mutants in which the ploidy level is altered or in which multiple nuclei were found revealed that some aspects of the cell cycle regulation are controlled by protein degradation. In this context we have identified a new protein degradation pathway so far unknown in plants.

Cell polarity is studied in trichome cells which establish several polarity axes during development. We have identified several new genes required; these point to novel, probably plant-specific mechanisms of polarity establishment.

Martin Hülskamp graduated with a PhD in Genetics from Munich where he worked on early Drosophila development. He then decided to work on plant development and switched to Arabidopsis thaliana as model system. Martin Hülskamp worked as a Post-Doc with Gerd Jürgens at the University of Tuebingen, and with Robert Pruitt at Harvard University. From 1994 to 2000 he ran a research group in the Department of Developmental Genetics at the University of Tübingen. Since 2000 he heads the Department of Botany III at the University of Cologne. He is a recipient of the Boehringer Ingelheim prize and serves as editor for Plant Physiology.