The Erwinia revolution 1
Group 5 Facultatively Anaerobic Gram-Negative Rods
The Erwinia revolution
Alphaproteobacteria – Rhizobiales Rhizobiaceae (Agrobacterium)
Betaproteobacteria – Burkholderiales Burkholderiaceae (Burkholderia,
Genera incertae sedis - (Xylophilus)
Gammaproteobacteria – Pseudomonadales - Pseudomonadaceae
Xanthomonadales – Xanthomonadaceae
Enterobacteriales - Enterobacteriaceae
Enterobacteriales – Gram-negative straight rods. Motile by peritrichous
flagella or nonmotile. Do not form endospores. Grow in presence or absence
Type genus - Escherichia
Much of information in this section extracted from:
S. H. De Boer, D. L. Coplin, and A. L. Jones. Erwinia and Pantoea. in: Laboratory rdguide for identification of plant pathogenic bacteria, 3 edition.
Erwinia, Brenneria, Pantoea, and Pectobacterium
Diseases caused by this group
； Soft rot
； Necrotic diseases
The Erwinia revolution 2
； Wilt diseases
The taxonomic position, nomenclature, and interrelationships of the members of the genus Erwinia have been the subject of diverse proposals. The broadest
classification is that of Dye (1968, 1969a, 1969b, 1969c), which separates Erwinia into
the pectolytic soft rot “carotovora” group, the yellow pigmented “herbicola” group,
the white nonpectolytic wilt-causing “amylovora” group, and the “atypical” Erwinia.
These have turned out to be valid clusterings based on DNA-DNA homology studies and 16S sequence homology (Hauben et al, 1998; Kwon 1997), but do not completely agree with purely phenetic groupings (Verdonck et al, 1987). Controversy remains on whether or not the differences are great enough to constitute new genera. On the basis of 16S rRNA sequence homologies, Hauben et al. (1998) recommended that these four groups be split into the genera Pectobacterium emend, Pantoea gen. nov., Erwinia emend., and
Brenneria gen. nov., respectively. For now the genus will remain intact with the exception of the group being placed in Pantoea.
The species and subspecies currently included in the pectolytic soft rot or
“carotovora” group have now been placed in Pectobacterium and include:
Pectobacterium carotovorum subsp. carotovorum, P. carotovorum subsp. atrosepticma, P.
carotovorum subsp. betavasculorum, P. carotovorum subsp. wasabiae, P. carotovorum
subsp. odoriferum, P. chrysanthemi, P. cypripedii, P. rhapontici and P. cacticida.
The species in the “amylovora” group will be considered together with the atypical erwinias and will include E. amylovora, E. persicina, E. pyrifoliae, E.
mallotivora, E. psidii, and E. tracheiphila.
E. alni, E. nigrifluens, E. paradisiaca, E. quercina, E. rubrifaciens, and E. salicis (24).
comprises the species included in the genus Brenneria.
It should be noted that G+C ratios do not entirely support the division of the Erwinia
species according to the presence or absence of pectolytic abilities, since they suggest a closer similarity between E. amylovora and E. chrysanthemi than between E. amylovora
and the other species of the “amylovora” group (21). Nevertheless, division of the
Erwinia genus on the basis of phenotypic characteristics is useful for grouping together those species that require similar protocols for their manipulation within the laboratory.
The “herbicola” group of yellow pigmented strains which consists of epiphytic
as well as plant pathogenic bacteria, has now been classified as Pantoea together with
some species of the genus Enterobacter (12, 16, 18). Initially, Ewing and Fife (1972)
using DNA-DNA homology data, recommended that Enterobacter agglomerans, E.
herbicola and E. milletiae be place in E. agglomerans. Gavini et al. in 1989
recommended that E. agglomerans (including the type species of E. herbicola and E.
milletiae) be transferred to the new genus Pantoea. Later, E. ananas and E. stewartii
The Erwinia revolution 3
were placed into Pantoea. The present genus Pantoea includes the phytopathogens P.
stewartii, P. ananas, P. citrea and P. agglomerans pvs. milletiae, gypsophilae and
Due to the heterogenity of the genus, a general description of Erwinia is
necessarily limited. As other members of the family Enterobacteriaceae, the erwinia occur
as straight rods (0.5-1.0 X 1-3 m) singly, in pairs, or sometimes in short chains, are
Gram negative and are motile by peritrichous flagella. They are facultatively
anaerobic, chemoorganotrophic, and grow optimally at 23-30?C. All species are
oxidase negative but catalase positive; nitrates are not reduced by most species. All
species catabolize glucose and various other carbohydrates with the production of acid but
usually without gas formation.
Much of information in this section extracted from:
De Boer, S. H. and A. Kelman.Erwinia soft rot group. in: Laboratory guide for rdidentification of plant pathogenic bacteria, 3 edition.
The species of the genus Pectobacterium comprise a distinct phylogenetic group as determined by 16S rRNA gene sequence comparisons
A. Erwinia Soft Rot Group
In 1945 Waldee stated that the soft-rot Erwinia species be placed in a separate genus, Pectobacterium although to date this has not been accepted. Other recommendations to place them in a
separate genus have lacked support (Mergaert et al, 1984). The soft rot or “carotovora” group
comprises those species which incite soft rot diseases of plants.
The following designations are used for the “carotovora” group:
- Pectobacterium carotovorum subsp. carotovorum * Widely distributed and most
- P. carotovorum subsp. atrosepticum * Primary cause of blackleg of potatoes.
- P. carotovora subsp. betavasculorum
- P. carotovorum subsp. wasabiae