Introduction

eurus 2brassinosteroids2The main interest of the group is the signal transduction pathway that plant cells use to respond to the growth promoting hormones, brassinosteroids.
Brassinosteroids are ubiquitously distributed throughout the plant kingdom sterol derivatives. Brassinosteroid deficient mutants display dramatic developmental defects including dwarfism, male sterility, delayed flowering, reduced apical dominance, and a light-grown morphology when grown in dark. Like their animal counterparts, brassinosteroids regulate the expression of numerous genes, impact the activity of complex metabolic pathways, contribute to the regulation of cell division and differentiation, and help control overall development. Brassinosteroids regulate photomorphogenesis, etiolation and cell expansion. Brassinosteroids have a broad spectrum of activities that have a positive effect on the quantity and quality of crops and they increase plant resistance to stress and pathogens.
The brassinosteroid pathway is one of the best-defined signal transduction pathways in plants. In Arabidopsis, brassinosteroids are perceived by receptor kinases that transduce the signal from the cell surface to the nucleus by an intracellular cascade of phosphorylation mediated protein-protein interactions, involving kinases, phosphatases, 14-3-3 proteins, and nuclear transcription factors. In addition, brassinosteroid signaling is regulated by the plant endocytic machinery because an increased endosomal localization of the brassinosteroid receptor enhances the signaling.
The main objective of the group is to combine genetic, molecular and cell biology tools to study the mechanism of brassinosteroid signaling regulation in plants. One aspect of the research is to understand the subcellular compartmentalization and trafficking of brassinosteroid receptor complexes and their relevance to brassinosteroids physiological responses. We use chemical genomics and proteomics to investigate the subcellular localization, mobility, transport routes and binding interactions of different brassinosteroid signaling components. In addition we want to position important downstream brassinosteroid signaling regulators such as the Arabidopsis GSK3-like kinases in subcellular compartments important for brassinosteroid receptor activity.
The potential application of brassinosteroids in agriculture is based not only on their ability to increase crop yields, but also on the fact that they increase resistance to different stress conditions, such as high salinity, drought, and fungal and viral infections. Thus, unraveling the regulatory mechanisms of brassinosteroid signaling on the level of signaling components, brassinosteroid target genes, and endomembrane trafficking regulators, or identifying chemicals that modulate any of those components can be used to develop selective strategies for high-yielding plants.