Final Activity Report Summary - SECRETION IN PLANTS (Development of new molecular tools to study secretion in plant cells) The goal of the project was the development of new molecular tools for the study of secretion in plant cells. The research work focused essentially on the characterisation of exocytose using exogenous molecular markers such as 'Intrinsically fluorescent proteins' (IFP) and enzymes (mannosidase and glucuronidase). Various aspects of protein sorting were considered, to the plasma membrane as well as to the alternative destination to the tonoplast. Collected data provided new information about the entire network of cell endomembranes.The new molecular tools developed during this project were of two kinds: new fluorescent markers, obtained as IFP chimeras, and new process-specific inhibitory molecules.The last kind of molecular tool consists of Dominant negative (DN) mutants obtained from Snares and Rabs involved in the different processes studied. The idea behind this move from the observation that inhibitory drugs specificity is dose dependent and difficult to establish in new systems. The use of a DN mutant can bypass the need of inhibitory drugs in studying secretory processes. In fact the expression in the cell system of a DN mutant can block the activity of proteic partners of the native protein with high efficiency and possibly no undesired effects.The use of DN mutants in other laboratories increased during the last years but the present project not only followed the most promising trend in this kind of studies but moved further validating with an original approach the use of more than one DN mutant at once.
