Drought stress signal is sensed either directly, e.g. in root cells, or indirectly through systemic spread of the signal by hormones and other messenger molecules, and the information is processed through complex signaling pathways to elicit growth adaptation responses. MAPK signalling pathways, a fundamental circuitry of stress signalling, constitute a hierarchical three-tiers system of protein kinases: MEKK, MEK and the MAPK, which phosphorylate specific substrate proteins, thereby changing cellular behavior. Both my lab in Szeged and the Bogre lab at Royal Holloway performed an- gene activation screening for stress-regulating processes, and found MKK7 and MKK9 and two downstream MAPKs, MPK3 and MPK6 to lead to stress adaptation and to regulate plant growth. The overall aim of the proposed research is to identify the targets of the MKK7/MKK9 – MPK3/MPK6 drought-responsive MAPK signaling pathway, and link these to the growth adaptation of plants under drought stress conditions. To do this we will perform: (i) unbiased phosphoproteomics screen for MAPK targets using mimicked drought conditions with mannitol treatment and the inducible MKK7/MKK9 lines, (ii) computational predictions of MAPK substrates involved in drought responses, (iii) targeted approaches to test MAPK phosphorylation of key regulators in plant growth regulation, the RBR transcriptional repressor complex. We aim to map the phosphorylation sites on RBR and DPB and on at least three newly identified MAPK substrates, mutate these sites and transform the mutant genes back to Arabidopsis wild type plants and into lines with altered MKK7/9 signaling pathway. Growth phenotyping of these lines under control and drought stress conditions should link this MAPK pathway to drought adaptation. In the course of the project I will obtain training in interdisciplinary research; proteomics, computational biology, and gain transferable skills to become an all rounded scientist.