EFFECT OF SEVERAL CHLOROPLAST ELECTRON TRANSPORT CHAIN INHIBITORS ON INTERACTION OF Erwinia amylovora WITH SUSCEPTIBLE AND TOLERANT APPLE AND PEAR CULTIVARS

Fire blight is important disease of pome fruit trees. The role of mitochondrial electron transport chain in interaction of host-pathogen has been verified. The purpose of this research was to study the role of chloroplast electron transport chain in this interaction and to determine the eventual site of pathogen effecter protein(s) influence. For this, effects of several chloroplasts electron transport chain inhibitors including Methylviologen, Glutaraldehyde and Diuron, with various sites of inhibition was evaluated on symptoms progress. All tests were performed and compared on in vitro shootlets of apples, MM-111 (tolerant) and MM-106 (susceptible) and pears, Harrow Sweet (tolerant) and Spadona (susceptible). For distinctness of necrosis causes by inhibitory effects inhibitors from those from pathogen, in a series of primary experiments, the effects of inhibitors concentrations were evaluated on shootlets in absence of pathogen and provided at least 168 h without necrosis of inhibitors. Subsequently, effects of inhibitors were evaluated on necrosis of pathogen after shootlets inoculation. The results showed that chloroplasts electron transport chain inhibitors retarded symptom progress in all tested cultivars. The results confirm previous results observed by uracil inhibition of chloroplasts and represent more evidence for role of this chain in host/E. amylovora interaction. In addition, according to impeding site of inhibitors, NADP reduction complex is the most probable site of effecter proteins interaction in host chloroplasts.