1988 Volume 54 Issue 2 Pages 189-197
The ice nucleation-active bacteria (INAB) isolated from gemmisphere of tea plants belonged to three genera; Erwinia (23 strains), Xanthomonas (44 strains), and Pseudomonas (1 strain). The strains of Erwinia isolated from tea fields in Shizuoka prefecture in 1978-1980, and in Kagawa pref. in 1987 were identified as E. ananas. An ice nucleation-active xanthomonad detected with a high frequency in Shizuoka pref. and Tokushima pref. in 1986-1987 was, however, identified as a strain of X. campestris from morphological, physiological, and biochemical traits. The bacterium was also found on some vegetables in Shizuoka pref. with a low frequency, but it was not pathogenic to any carrier plants from which it was isolated. The taxonomic affiliation of this bacterium was left for future study, although the new subspecific rank was suggested to be more eligible than the pathovar rank. The strains of INAB isolated from flowers of Magnolia denudata and leaves of various vegetables in Shizuoka pref. and a strain isolated from tea gemmisphere in Kagawa pref. were identified as P. syringae. Although they were identical either with P. syringae pv. delphinium (17 strains) or P. syringae pv. syringae (1 strain) in biochemical tests, all strains were not pathogenic to any carrier plants and Delphinium spp. as well. However, all of six strains that were arbitrarily selected, formed water-soaked lesions on the leaves of lilac (Syringa vulgaris L.) through stomata and wounds. Therefore, these strains were identified as P. syringae pv. syringae. A strain of INAB isolated from Wasabi petiole was a non-fluorescent pseudomonad with positive tobacco HR. Although the diagnostic traits of the bacterium were similar to those of P. cichorii, it showed no pathogenicity to any plants tested including Wasabi and lettuce. Therefore, its taxonomic affiliation was left for future study. All INAB mentioned above showed the type A ice nucleation-activity, i.e. the supercooling temperature was between -2.8 and -3 C except for the Wasabi pseudomonad at -4 and -5 C.