BACTERIAL CANKERS CAUSED BY PSEUDOMONAS SYRINGAE ON STONE FRUIT SPECIES WITH SPECIAL EMPHASIS ON THE PATHOVARS SYRINGAE AND MORSPRUNORUM RACE 1 AND RACE 2
A. Bultreys, M. Kaluzna
Bacterial canker of stone fruits caused by Pseudomonas syringae pv. syringae and pv. morsprunorum has been studied for a century now and this research brought decisive advances in the understanding of the epidemiology of foliar bacterial diseases and epiphytic stages in the life cycles of plant pathogenic bacteria. The economic importance of the disease and lack of effective control measures stimulated recent studies on the ecology of the pathogens and their characterization and identification. New techniques of identification are based on the ecologically and pathologically important siderophores pyoverdine and yersiniabactine, and phytotoxins including coronatine and toxic lipodepsipeptides. Genetic methods based on total DNA homology, repeated sequences (rep- PCR), melting profiles (PCR MP) and DNA sequencing (MLST) proved the existence of three distinct pathogens: races 1 and 2 of pathovar morsprunorum, each genetically homogenous, and pathovar syringae, highly heterogeneous. In both pathovars, genetic groups differing in their pathogenicity were determined and isolate-host relationships pointed out.