Plants need highly efficient responses to adverse environmental conditions as they are bound to a single location.These adaptive processes are not only important in the acute phase of the stress but are in natural environments discriminative for plant fitness and in agricultural systems determining yield. Reprogrammed metabolism is an important part of stress adaption. Even small changes in metabolic reactions can cause dramatic changes in levels of key metabolites, which may change the physiology and growth of the plant.The long time goal of the group is to understand this highly dynamic network of metabolites, enzymes and most importantly - How is the adaptive growth of plants is regulated?
Adverse conditions results often in limited energy availability and plant cells respond to this by reprograming their metabolism to better fit the new situation.This dramatic change involves hundreds of gene products and metabolites; we call this the Low Energy Syndrome, LES. The change is mastered by the SnRK1 kinase complex, which is able to react to lo levels of metabolizable sugars. This parallels the manner in which all eukaryotes regulate starvation responses. In plants the SnRK1 kinases regulate gene expression of genes encoding key meta- bolic enzymes by activating certain bZIP transcription factors. One of our projects focuses on these transcription factors.We are interested in their mode of action and how their activity is regulated.Technically we are using high throughput expression analysis (micro-arrays, massive sequencing) as central analysis ool combined with genetics and transgene based methods.
When conditions are favorable for plant growth the SnRK1 complex is deactivated and a second major signaling system takes over mastered by another kinase - The Target of rapamycin, TOR that is positively regulates growth in all eukaryotes.TOR does so partly by regulating translation, which is a very energy consuming process and is therefore tightly regulated.The second project in the laboratory deals with the regulatory mechanism of translational control by focusing on the activity of the ribo- some.We currently are identifying novel components involved in translational changes using transcriptomics, translatomics, proteomics and genetic methodology.
The growing population of this planet will change our socie- ty. It is clear that food, feed and other plant-based resources will be limiting in the future.The grand challenge is to increase plant production a sustainable way.The transition to less fossil fuel dependent production will challenge our agricultural systems even further. Consequently, there is a basic need to optimize plant growth.This can be done by changed growth practices and reducing post harvest losses, etc. However, we can not reach our goals without crop improvement, similarly to what happened during the green revolution half a decade ago.This is not limited to classical crops.We will need novel corps for biomass, bioenergy and biorefinery needs. By understanding the underlying mechanisms of growth control we hope to find new ways to improve plant based production.
- Hummel, M., Cordewener, J.H., de Groot, J.C., Smeekens, S.C.M., America, A.H., and Hanson, J. (2012). Dynamic protein composi- tion of Arabidopsis thaliana cytosolic ribosomes in response to sucrose feeding as revealed by label free MSE proteomics. Proteomics 12: 1024–1038.
- Ma, J., Hanssen, M., Lundgren, K., Hernandez, L., Delatte, T., Ehlert, A., Liu, C.M., Schluepmann, H., Droge-Laser, W., Moritz, T., Smeekens, S.C.M., and Hanson, J. (2011). The sucrose-regulated Arabidopsis transcription factor bZIP11 reprograms metabolism and regulates trehalose metabolism. New Phytol 191: 733–745.
- Rahmani, F., Hummel, M., Schuurmans, J.A., Wiese-Klinkenberg, A., Smeekens, S.C.M., and Hanson, J. (2009). Sucrose control of translation mediated by an upstream open reading frame-encoded peptide. Plant Physiol 150: 1356–1367.
- Smeekens, S.C.M., Ma, J., Hanson, J., and Rolland, F. (2010). Sugar signals and molecular networks controlling plant growth. Current opinion in plant biology 13: 274–279.
- Hanson, J. and Smeekens, S.C.M. (2009). Sugar perception and signaling--an update. Current opinion in plant biology 12: 562–567.