Articles
CHARACTERIZATION OF BACTERIA THAT CAUSE “BACTERIAL SHOOT BLIGHT OF PEARD” IN JAPAN
Several reports describing the disease were made in the Japanese literature starting in the early 1900’s (reviewed by Keil and van der Zwet, 1979). However, the Japanese Government stated (Anon, 1974) that previous reports of the occurrence of fire blight had been based on faulty identification and the disease had never existed in Japan.
Thus, fire blight workers have considered Japan together with South Africa, Australia, China and Chile, as important pome-fruit growing countries that should guard against introduction of the disease (Deckers, 1993).
The question of the possible existence of fire blight in Japan arose anew following the publication of an English translation of a Japanese textbook (Goto, 1992). Goto described a disease, similar to fire blight, called "bacterial shoot blight of pear" (BSBP) that occurred on the northern Japanese island of Hokkaido.
The symptoms of the disease were described as "identical to those of fire blight", and the disease reportedly was caused by a bacterium that "is identical to Erwinia amylovora except for some bacteriological and serological properties". The pathogen was said to infect only certain cultivars of oriental pear and not apple.
We studied the only known surviving strain from the 1970’s epidemic of "bacterial shoot blight" and several other strains isolated more recently from symptomatic pear blossoms, fruits and shoots on Hokkaido.
Our studies included tests of microbiological, serological, and molecular genetic properties and the host-specificity of the strains.
The BSBP strains were tested in comparison with several authentic strains of E amylovora from Europe, North America, New Zealand and the Middle East.
The results of some of these studies are included in other reports in this volume (Kim et al., 1996; Momol et al., 1996) and are summarized here.
Based on traditional bacteriological tests, carbon source utilization as determined with the BiOLOGTM system (Bochner, 1989), hybridization of genomic DNA with the cloned hrp gene cluster of E. amylovora, we concluded [as did Tanii and co-workers earlier (Tanii et al., 1981)] that the “bacterial shoot blight” pathogen is E. amylovora. The strains from Hokkaido clearly had properties in common with the 76 other strains of E. amylovora included in our studies.
These had been isolated from a variety of hosts and