||Crop yields are largely dependent on their tolerances to environmental influences, including salinity. Previously, we have shown that the Arabidopsis synaptotagmin 1 (AtSYT1), the most abundantly expressed Arabidopsis ortholog of the well-known calcium sensors in animal neurons, is involved in responses to abiotic stresses. The general goal of this proposal is to reveal the mechanisms by which AtSYTs regulate the reactions to high salinity and other stresses. We wish to characterize AtSYTs expression, describe phenotype of Atsyts mutant lines, to study subcellular localisation of AtSYTs, and to monitor intracellular dynamics of AtSYT1. Additionally, we shall address the functional analysis of the interaction fished out in the yeast two hybrid assay connecting AtSYT1 to the MAPK cascade. Our study will contribute to the overall understanding of how membrane trafficking is involved in stress responses.