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Erwinia is a genus of Enterobacteriaceae bacteria containing mostly plant pathogenic species which was named for the first phytobacteriologist, Erwin Smith. It is a gram negative bacterium related to E.coli, Shigella, Salmonella and Yersinia. It is primarily a rod-shaped bacteria. A well-known member of this genus is the species E. amylovora, which causes fireblight on apple, pear, and other Rosaceous crops. Erwinia carotovora is another species, which causes diseases in many plants. These species produce enzymes that hydrolyze pectin between individual plant cells. This causes the cells to separate, a disease plant pathologists term plant rot.
[edit] Erwinia carotovora
This bacteria is a plant pathogen with a wide host range (carrot, potato, tomato, leafy greens, squash and other cucurbits, onion, green peppers, etc.), able to cause disease in almost any plant tissue it invades. It is a very economically important pathogen in terms of postharvest losses, and a common cause of decay in stored fruits and vegetables. Decay caused by E. carotovora is often referred to as bacterial soft rot (BSR). Most plants or plant parts can resist invasion by the bacteria, unless some type of wound is present. high humidity and temperatures around 30C favor development of decay. Mutants can be produced which are less virulent. Virulence factors include: pectinases, cellulases, (which degrade plant cell walls), and also proteases, lipases, xylanases and nucleases (along with the normal virulence factors for pathogens – Fe acquisition, LPS integrity, multiple global regulatory systems).
