Research Abstract |
A new bacterial disease with gall formation on either trunks or twigs was found on Sharinbai(Rhaphiolepis umbellate Makino) trees growing in Okinawa and Kagoshima Prefecture, Japan. The surface of young galls was relatively smooth and light-green in color, but they became rough and light-brown to dark-brown with age. A pathogenic bacterium isolated from these galls was gram-negative rod with 1 to several polar flagella, aerobic and metabolized glucose oxidatively. Negative results were obtained with the tests such as kovacs oxidase, levan production, potato soft rot, hydrolysis of esculin and starch, arginine dihydrolase, production of H_2S, nitrate reduction, KCN inhibition, indole production, gelatin liguefaction, methyl-red and Voges-Proskauyer tests and growth at 41゜C and 4゜C. Positive results were obtained with the tests such as catalase, tobacco hypersensitive reaction, hydrolysis of Tween 80, reducing substances from sucrose and fluorescent pigment production. Following organic compounds were utilized as a sole source of carbon : ribose, glucose, D-mannose, D-xylose, fructose, glycerol, D-sorbitol, mannitol, citrate, succinate, L-malate and L-, meso-tartrate. Followings were not utilized : sucrose, D-,L-arabinose, L-rhamnose, Dk-galactose, lactose, maltose, D-cellobiose, melibiose, D-trehalose, dextrin,glycogen, maltose, starch, inulin, inositol, adonitol, dulcitol, salicin, malonate, lactate, L-Valine, L-Arginine and <beta>-Alanine. Inoculation tests for the host range of the Sharinbai pathogen were conducted on trees of 105 species belonging to 44 families. The disease development was confirmed only on Rhaphiolepis umbellata, but not on other trees, From these results, the Sharinbai pathogen was identified as a new pathovar of Pseudomonas syringae. The name of P. syringae pv. rhaphiolepidis Pv. nov. will be soon proposed to ATCC, NCPPB, PDDCC and the strain RU 2 will be designated as the pathotype strain.
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