THE GENOMIC SEQUENCE OF THE FIRE BLIGHT ANTAGONIST ERWINIA TASMANIENSIS COMPARED WITH VIRULENCE REGIONS OF E. AMYLOVORA

Erwinia tasmaniensis interferes with colonization of plant tissue by Erwinia amylovora. The first strains of this species were isolated from apple and pear flora in Australia. They belong to the genus Erwinia, produce levan and cause a hypersensitive response (HR) in tobacco leaves, especially when grown in HR-inducing medium. The genome of the E. tasmaniensis strain Et1/99 has been sequenced and annotated. The hrp/dsp-region, the ams/cps-region and the pst/glmS-region with the levansucrase gene were also characterized for the German E. amylovora strain Ea1/79 and the American Rubus-pathogenic strain MR1. Furthermore, these regions were sequenced for E. pyrifoliae strains from Korea and Japan and the epiphytic E. billingiae strain Eb661 from England. The lsc gene is not present in E. pyrifoliae and E. billingiae. All analyzed strains carry an EPS-encoding region with high homology to the ams-cluster of E. amylovora. Synthesis of the capsular EPS related to amylovoran of E. amylovora has not yet been found for strain Et1/99. Furthermore, E. tasmaniensis cannot metabolize sorbitol, and the corresponding gene cluster is completely missing in the genome. The hrp/dsp region is highly related among most of the analyzed Erwinia species but is absent in the genome of E. billingiae. Besides the 4 Mb chromosomal sequence, five plasmids were characterized for strain Et1/99, which encode gene functions for autonomous plasmid transfer, for bacteriocin-like proteins and for synthesis of antibiotic precursors. Besides two copies of hns-like genes on the chromosome of Et1/99, one plasmid carries a third gene of the global regulator.