EXTRACELLULAR ENZYMES AND PATHOGENESIS OF SOFT-ROT ERWINIA

Abstract

Historically the genus Erwinia has served as a repository for plant-pathogenic or plant-associated bacteria (25, 96, 128). Consequently, diverse bacteria that occupy different habitats on or within plants and plant remains have been lumped into this genus. Their diversity is also reflected in the range of symp­ toms, i.e. necrosis, wilts, galls, and rots elicited in a wide range of plants. This diversity notwithstanding, these bacteria are related genetically to other en­ terobacteria such as Escherichia coli and Salmonella typhimurium that have served well as model systems for genetic and physiological studies. Microbi­ ologists and plant pathologists alike were initially attracted to Erwinia because of the potential for the use of genetic tools developed for the E. coli system. Thus, several Erwinia species were selected as model systems for the analysis