Signal transduction in cell separation processes- A novel, important signaling module in plants possibly involving RLKs, RopGEFs and RAC/ROP

Cell-to-cell communication is a necessity in plants during development and differentiation. Small peptides can function as signaling molecules. To function in cell-to-cell signaling theses small peptides must have properties that allow them to be transpor ted from the cytoplasma and out across the plasma membrane. Cell-to-cell signaling is transduced for instance via receptor kinases and small GTPases, into changes in gene expression, thus providing the cell receiving a signal with novel gene functions. In this project we will investigate the signaling circle of a novel class of small peptides involved in abscission and related processes in the model plant Arabidopsis thaliana. The INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) protein and five IDA-LIKE (IDL) proteins have been suggested to act as peptide ligands. We aim at identifying their biological function, their receptors, their transport routes, their downstream signaling cascade and their influence on gene expression. The two collaborating groups hav e complementary expertise which makes it possible to enter a more holistic study of the signal transduction module. Aalen group has for some time been studying the genetic and developmental control of floral abscission and have identified a family of smal l peptides that may act as ligands. Bones group has studied the genetics and molecular function of the RAC/ROP GTPases, interacting partners and their role in intracellular transport. Both groups have used a genetic approach, but in addition Boneslab has expertise in transcriptional profiling, bioinformatics and intracellular transport, and Aalen lab has expertise in protein-protein interaction studies (yeast two hybrid). The project will take advantage of the expertise and services of the Norwegian Arabi dopsis Research Center (FUGE-NARC) which are hosted by the applicants. It is our opinion that joining forces will advance Norwegian functional genomics.