Pathogenicity, preservation and role of bacteriophage of Xanthomonas campestris pv. phaseoli (Simth) Dye
1986
Anong Jankittivong
Four isolates such as 002 and 008 from Thailand and 023 and 036 from Japan, which were characterized and identified virulent were inoculated on 6 varieties of soybean to test their pathogenicity. The result showed that 4 varieties from Japan, Yukimusume, Tamasudare no.2, Sosei edamame and Bien green, were highly tolerant with few pustule lesion per leaf, while 2 varieties from Thailand, S.J.4 and S.J.5 were moderately susceptible when compared 3 tolerant Japanese varieties including the susceptible one, Bien green. Comparative study on 5 methods for preservation of the pathogen by mean of survival and virulence during 6 months was conducted. The investigation revealed that lyophilization was the most effective preservation while the others skim milk, mineral oil and distilled water gave sequentially good result , except sterile soil which failed to preserve this pathogen since the bacteria was inactivated after 3 months of preservation. The role of bacteriophage by mean of isolation of bacteriophage from infected soybean leave and growing diseased soybean soil, was also studied. Three type of plaques with 2.5-3.0 mm, 1.5-2.0 mm and very small plaques in diameter were discovered. The effect of temperature, pH condition and alcohol on the inactivated point of phage was investigated. The results showed no difference due to the mentioned factors between Thai and Japanese phage. Both of them were completely inactivated in 10 minutes under 60 deg. celsius, pH 7.0 and 90 % ethyl alcohol.
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