Final Activity Report Summary - ARA-MKK-D (A bioinformatics and systems biology approach for the functional analysis of a growth-regulating MAP kinase pathway in Arabidopsis) Morphogenesis in plants differs from the process in vertebrates, because it is mainly postembryonic and continues throughout the life of the plant. Furthermore, organogenesis and growth in plants show a remarkable plasticity to allow adaptation to changing environmental conditions, including changes in light, temperature and response to stressful conditions such as pathogens or limited water availability. This regulation is especially important as human life depends on the production of plant materials and they are now being explored as a source of non-fossil fuels as well. This project focused on regulatory mechanisms in the model plant Arabidopsis thaliana that control the growth and developmental processes in response to environmental stresses.Protein kinases are enzymes that transfer phosphate groups to other protein molecules and thus can change their stability, activity or localisation within the cell. Protein phosphorylation is therefore an important regulatory mechanism in all cell types. Mitogen activated protein (MAP) kinases are a group of protein kinases found in all eukaryotes from yeast to plants and mammals. They transfer extracellular stimuli via protein phosphorylation cascades into cellular and molecular responses that bring about adaptation.We generated transgenic Arabidopsis lines that overexpress MAP kinase components under the control of a switch-like inducible system. This allowed us to study how they control developmental and molecular processes, by comparing induced and non-induced materials. Such way we identified a specific MAPK pathway that when activated rapidly arrested plant growth and led to reprogramming gene expression similar to environmental stresses, indicating that the MAP kinase signalling components, MKK7 and MKK9, function in a regulatory switch that halts growth and induces defence responses when activated by stresses.Moreover we gained further insight into the complexities of MAP kinase signalling networks by computational analyses of large scale experimental data sets. In the long run detailed understanding of mechanisms that link stress signalling to developmental processes in plants may facilitate crop breeding to generate more resistant varieties without compromising plant growth and yield.
