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Our main areas of research are:

-  Protein ubiquitination in light signal transduction

-  Light-controlled plant development

-  Evolution of light signaling

-  Light-auxin cross talk in the differentiation of stomata

Sunlight is the primary source of energy for plants.  Therefore, plants have evolved a variety of mechanisms to adapt growth and development to the ambient light conditions, with the aim to optimize growth and - ultimately - seed production in a competitive environment.  We are interested in identifying and understanding the genes and proteins that underlie these adaptive developmental responses to light.  To this end, we are - mostly - using the model species Arabidopsis thaliana and a combination of genetic, molecular and biochemical approaches.

Plants see the light conditions through a number of photoreceptors that initiate a signaling cascade resulting in vast changes in gene expression. Our research focuses on the proteins involved in the light signaling cascade.  In particular, we analyze an E3 ubiquitin ligase (COP1/SPA complex) that controls the degradation of transcription factors during light signal transduction.  Here, we focus on the regulation of COP1 activity by SPA proteins and light. 

We also investigate the evolution of the COP1/SPA complex.  While the COP1 gene also exists in humans where it controls processes such as cell division and - possibly - tumor suppression, SPA genes are specific to plants.   By analyzing COP1 and SPA function in the early land plant Physcomitrella patens (a moss) and the perennial Brassicaceae Arabis alpina, we aim to understand why SPA genes evolved in the green lineage.

Light conditions initiate a large number of adaptive responses.  Examples are an increased stem elongation in shady conditions, a higher number of stomata and thickening of leaves in the light, and a regulation of flowering time by day length.  To understand how a common set of photoreceptors can induce such diverse responses throughout plant development, we analyze the functions of transcription factors in light signaling. Moreover, we investigate the cross talk between light and the hormone auxin in stomata differentiation and shade avoidance.