Abstract
Following to the previous studies on bacterial canker of Japanese apricot (Prunus mume Sieb. et Zucc.), 31 pathogens isolated from shoots and fruits of Japanese apricot were compared their bacteriological characters with Pseudomonas syringae pv. syringae NCPPB 524 and P. syringae pv. morsprunorum NCPPB 330. All the isolates were short rod-shaped, aerobic, Gram-negative and motile by one to several polar flagella. They metabolized glucose oxidatively and showed catalase activity, and produced levan. They showed negative reaction on VP-MR tests, oxidase and arginine dihydrolase activities, and did not produce hydrogen sulfide or indole. They produced acid from arabinose, xylose, mannose, fractose, glucose, sucrose, cellobiose, ribose, glycerol, mannitol, sorbitol and inositol, but not from maltose, melezitose, dextrin, galactitol, adonitol, α-methylglucoside or salicin. They were divided into three groups (A, B and C) by the differential tests for distinguishing P. syringae pv. syringae and P. syringae pv. morsprunorum which consist of bacteriological tests such as growth in sucrose broth, longevity on nutrient sucrose agar, liquefaction of gelatin, hydrolysis of aesculin and arbutin, pigment on tyrosine, pigment on King's B and utilization of lactic acid and tartaric acid. Group C bacteria (27 isolates) were characterized to be quite similar to those of pv. morsprunorum in differential tests and pv. morsprunorum NCPPB 330, a check strain. The other two groups bacteria (A and B, 2 isolates respectively) were different from group C in some bacteriological characters. The 31 isolates and the 2 check strains were proved to show virulence to immature green fruits of Japanese pear and overwintered twigs of Japanese apricot, but to be avirulent to lilac leaves. On the basis of bacteriological characters and pathogenicity, group C bacteria were identified as Pseudomonas syringae pv. morsprunorum (Wormald 1931) Young, Dye and Wilkie 1978, and group A and B bacteria as its strain.
