A high correlation was found between rotting ability of potato tuber and polygalacturonase (PG) production in Burkholderia glumae. PG was always detected in rotted potato tissues infected with virulent strains. For isozyme analysis of PG produced by B. glumae, proteins obtained from potato rotting tissues and culture filtrates were subjected to native-polyacrylamide gel electrophoresis and assayed with an ultrathin polygalacturonic acid-agarose overlay stained with ruthenium red. Two bands of hydrolytic activity were detected, indicating that B. glumae produces at least two isozymes of PG.

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Restriction fragment length polymorphism (RFLP) analysis for an internal transcribed spacer region (5S plus ITS 1 and ITS 2) of ribosomal DNA (rDNA) repetitive units amplified by the polymerase chain reaction (PCR) was used for rapid distinction of Burkholderia glumae, B. gladioli, B. plantarii and B. vandii, causal agents of various diseases. The RFLP profiles obtained after digestion of the ITS regions amplified by PCR with Hha I and Sau 3AI seemed useful for rapid distinction of these species. PCR-RFLP with Hha I and Sau 3AI for DNA samples from rice leaf-sheath tissues inoculated with B. glumae or B. gladioli and the corresponding bacterial cells cultured showed identical polymorphisms. The possibility of direct distinction of these pathogenic bacteria from naturally infected rice plant tissues by this method was demonstrated.

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To investigate the genetic variation among Japanese isolates of the southern rust pathogen of corn, Puccinia polysora UNDERWOOD, the RFLP of the 5.8S rDNA plus ITS1 and ITS2 regions was analysed. The ITS regions of 14 P. polysora isolates and a P. sorghi isolate were succesfully amplified with whole DNAs extracted from infected leaves. When the ITS regions of the P. polysola isolates were restricted with Hae III, Mbo I, Nla III or Taq I, two RFLP patterns were detected. Results suggest there were at least two genetic groups in Japanese P. polysola. Each group consisted of isolates from different locations and dates of collected. P. polysola could easily be distinguished from P. sorghi by the RFLP patterns of the ITS regions.

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The pathogenesis of twenty-eight isolates of Plasmodiophora brassicae WORONIN obtained from thirteen prefectures, to the WILLIAMS' race differential hosts and clubroot-resistant (CR) cultivars of Chinese cabbage were investigated. The pathogenesis of seven isolates from Chugoku and Kyushu areas were tested also to CR cultivars of cabbage. Twenty-six isolates were identified as race 4, suggesting that race 4 is the most dominant in Japan. Remaining two isolates were race 9 (or race 3) and race 1, respectively. Seven race 4 and one race 9 (or 3) isolates showed pathogenicity to CR cultivars of Chinese cabbage, Kukai 70 and/or Horai San-go, whereas nineteen race 4 and one race 1 isolates hardly showed pathogenicity to these cultivars. Of seven isolates from Chugoku and Kyushu areas, three (race 4) were moderately pathogenic to CR cultivars of cabbage, YCR Tae and YCR Tamu; three isolates (race 4) were moderately pathogenic to YCR Tae but non-pathogenic to YCR Tamu; and one (race 9 or 3) was non-pathogenic to both cultivars. The results indicate that race 4 isolates are not uniform in pathogenicity to CR cultivars of Chinese cabbage and CR cultivars of cabbage.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Seven types of plastic soft drink bottles were utilized as traps for the golden apple snail, Pomacea canaliculata (LAMARCK). The number of snails caught using the bottle traps were compared with the number of snails caught using the box type trap manufactured by Kyushu Sankyo Co. Ltd. The traps were installed 14 times in a paddy rice field in Koushi, Kyushu, southern Japan from June to July 1997. A total of 424 snails were trapped. The FRIEDMAN statistical test showed no significant difference in the number of snails caught using the two types of trap. Incidentally, there is a wide fluctuation in daily snail catch. The number of snails caught in plastic bottle traps were greater than those caught in box type trap. Moreover, the bottle type trap was simpler than the box type trap. Hence, the bottle trap may be recommended as a practical means of trapping snails in the field.

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Conditions in the extraction of DNA and amplification of DNA fragments were determined in the golden apple snail Poinacea canaliculata (LAMARCK) (Gastropoda: Ampullariidae). Using random primers of 10 nucleotides, DNA fragments were successfully amplified with template DNAs from both fresh and ethanol (99%)-preserved snails. A high interspecific variation was detected when the random amplified polymorphic DNA (RAPD) profiles of P. canaliculata were compared with those of the other ampullariid Pila conica (GRAY) and the vivipariid Cipangopaludina japonica (MARTENS). RAPD profiles were also different among populations of P. canaliculata collected from Kumamoto, Iriomote Island and Luzon Island and among individuals in the same populations. The techniques developed in this study are useful in elucidating phylogenetic relationships among apple snails and in analyzing their mating systems and population structures.

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[in Japanese]

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Control of the root-knot nematode, Meloidogyne incognita race 1 was conducted by the nematode-parasitic bacterium, Pasteuria penetrans in sweet potato field plots. The plots were enriched with P. penetrans for five consecutive cropping seasons. The sweet potato cultivars tested include the moderately resistant Beniazuma and the highly susceptible Kokei 14. P. penetrans significantly inhibited the propagation of the root-knot nematodes. Marketable yields of fleshy storage root increased remarkably in the P. penetrans enhanced plots: 4 to 5 times greater than the control treatments for Beniazuma, and 10 to 13 times greater than the control treatments for Kokei 14. The controlling efficacy of P. penetrans was almost equivalent to that of 1, 3-D, particularly for Beniazuama.

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The distribution of two weevil species, Cylas formicarius FABRICIUS and Euscepes postfasciatus FAIRMAIRE, and their damage to sweet potato were investigated in the Amami Islands in 1997. The population density of C. formicarius male adults was determined using synthetic sex pheromone traps at 127 sites in November. The weevil density was higher in Amami-Ooshima Island and Kikai Island than in the other islands. The infestation of sweet potato by C. formicarius and E. postfasciatus were investigated at 148 fields from October 1997 to March 1998. An average of 18.8% sweet potato tuberous roots were infested with weevils. Tuberous root damage were more serious in Okierabu Island and Yoron Island. Both weevil species were found in all towns of the Amami Islands.

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[in Japanese]

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