Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Volume 61 , Issue 6
Showing 1-19 articles out of 19 articles from the selected issue
  • Masamichi ISOGAI, Fumio AZUHATA, Ichiro UYEDA, Eishiro SHIKATA, Ikuo K ...
    1995 Volume 61 Issue 6 Pages 513-518
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    By polyacrylamide gel electrophoresis (PAGE) and nucleic acid hybridization, the extent of genomic relatedness between rice black-streaked dwarf Fijivirus (RBSDV) and maize rough dwarf Fijivirus (MRDV) was investigated. It was previously reported that RBSDV S7 and S8 correspond to MRDV S6 and S7, respectively, based on nucleotide sequences (Marzachí et al., Virology, 1991). However, present comparison of the genomic segments of the two viruses in polyacrylamide gel electrophoresis together with the hybridization studies with the cDNA probes showed correspondence of the two virus segments as RBSDV S7-MRDV S7 and RBSDV S8-MRDV S8. Hybridization studies using cDNAs to all the RBSDV segments except for S3 as a probe showed that extent of sequence relatedness was found to differ among the segments. Partial cDNA clones to RBSDV S1, S4, S5 and S6 reacted substantially weaker to MRDV genome than those to the other segments tested. And the cDNAs to the RBSDV S5 and S6 were found to be useful to differentiate the two viruses.
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  • Kazuo NAKASHIMA, Takaharu HAYASHI, Witcha CHALEEPROM, Porntip WONGKAEW ...
    1995 Volume 61 Issue 6 Pages 519-528
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Sesame phyllody (SP) caused by phytoplasmas occurs in many countries in the tropics. DNA extracted from sesame plants with phyllody in Thailand, purified for the phyllody-specific fraction with repeated bisbenzimide-CsCl equilibrium density gradient centrifugation and fragmented by restriction enzyme HindIII was cloned into a plasmid-Escherichia coli system. Recombinant plasmids which reacted with the peroxidase-labeled DNA of SP-affected sesame plants but not with the labeled DNA of healthy sesame plants were selected. Southern analysis revealed that the inserts of some recombinant plasmids consisted of fragments of chromosomal DNA of the phytoplasma, whereas the inserts of the other recombinant plasmids consisted of fragments of two types of extrachromosomal DNAs of the phytoplasma. Hybridization using the cloned chromosomal and extrachromosomal DNA fragments associated with the SP phytoplasmas as probes as well as the PCR procedure to amplify the 16S rDNA of phytoplasmas was effective in assaying SP phytoplasmas in the field. Cloned DNA probes hybridized strongly with SP specimens whereas most of them hybridized weakly with rice yellow dwarf, sugarcane white leaf, gentian witches' broom, and tsuwabuki witches' broom specimens. Preferential dot hybridization and restriction enzyme cutting pattern analysis of the 16S rDNA of several phytoplasma isolates found in Northeast Thailand indicated that the SP phytoplasmas are more closely related to some phytoplasmas associated with phyllody and witches' broom type symptoms than to phytoplasmas associated with white leaf symptoms including sugarcane white leaf phytoplasma.
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  • Hiroshi YANO, Kazuyuki HIRAYAE, Tadaaki HIBI
    1995 Volume 61 Issue 6 Pages 529-535
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Restriction fragment length polymorphisms (RFLP) of phytopathogenic pseudomonads were analyzed by Southern hybridization using biotinylated Escherichia coli 16S+23S rRNA as a probe. HindIII digests of total DNAs from 58 isolates including 11 species and 13 pathovars of pseudomonads showed extensive diversity and specificity of the rRNA gene RFLP patterns for the individual species and pathovars. These results suggest that this nonradioactive, simple and rapid method can be used for the practical discrimination of phytopathogenic pseudomonads.
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  • Ken'o OKAYAMA, Tomohiko NAKANO, Sachiko MATSUTANI, Teruhiko SUGIMURA
    1995 Volume 61 Issue 6 Pages 536-540
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A simple and reliable method was established for evaluating fungicide efficacy in the control of strawberry powdery mildew. The lower surface of newly developed leaflets of strawberry runner-tip plantlets was the best for assay inoculation, and disease severity could be visually evaluated with ease 7 days after inoculation. The youngest leaflets were more susceptible than the intermediate leaflets, and the oldest leaflets were hardly infected by the fungus. The colonies on the inoculated lower surface of runner-tip plantlets were observed clearly 7 days after inoculation and remained alive for 28 days. Disease severity was consistently high when sprayed with conidial suspension containing more than 5.0×104 conidia/ml. Maximum infection of inoculated leaflets was observed when incubated at near 20°C. Infection frequency at 15°C was greater than at 25°C. No disease development was observed at or above 30°C. When leaflets were sprayed with effective fungicides before inoculation, disease development was remarkably suppressed. The effects of fungicide were more clearly evaluated with leaflets in test tubes than those on whole plants in the vinyl-covered house. These results indicate the validity of this method for the accurate evaluating of fungicide effectiveness. This method will be adapted to the screening of fungicides for powdery mildew control.
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  • Toshiaki TAKEHARA, Katsuto KUNIYASU
    1995 Volume 61 Issue 6 Pages 541-548
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Properties of nitrate nonutilizing (nit) mutants of Fusarium oxysporum were compared to those of wild-type strains using F. oxysporum f. sp. raphani, f. sp. spinaciae, and a nonpathogenic strain of F. oxysporum (S-52). Most mutants showed the same growth as the wild-type strain on potato sucrose agar (PSA) medium, though some mutants from F. oxysporum f. sp. spinaciae showed slower growth. No difference was observed in the proliferation in liquid medium or sterilized soil between nit mutants and the wild-type strain for the strains tested. All of the 24 mutants from benomyl-sensitive F. oxysporum f. sp. raphani were also benomyl-sensitive. Most of the 43 mutants from f. sp. raphani and f. sp. spinaciae retained pathogenicity to their respective hosts, although two mutants from f. sp. spinaciae had clearly weakened pathogenicity. Among the total of 195 mutants from 10 formae speciales, most mutants retained their phenotypes at their formation even after three-year preservation by subculture on slanted PSA at room temperature, while 21 mutants (10.8%) changed their phenotypes and recovered the ability to utilize nitrate. When nit mutants of f. sp. raphani were inoculated into nursery soil and reisolated three years after inoculation by soil dilution plating, all of the reisolated F. oxysporum were still nit mutants and no phenotypic change was observed. Population densities of the mutants in the soil were at almost the same level as for the wild-type strain. When mutants of f. sp. spinaciae were inoculated to spinach, reisolated, and tested for their phenotypes, all of the mutants retained their original phenotypes. Thus, although some nit mutants had weakened pathogenicity or were unstable, most nit mutants had the same properties as wild-type strain and were stable over long periods of time. It is thus assumed that nit mutants can be used as markers in ecological studies of F. oxysporum.
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  • Yukio TOSA, Hitoshi NAKAYASHIKI, Hideyuki HYODO, Shigeyuki MAYAMA, Haj ...
    1995 Volume 61 Issue 6 Pages 549-554
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Distribution of retrotransposon MAGGY in Pyricularia species isolated from various monocot plants was investigated. MAGGY was present in a high copy number in isolates from rice, foxtail millet (Setaria italica), and green bristlegrass (S. viridis), but absent in those from wheat, finger millet, goosegrass, crabgrass, Digitaria horizontalis, and mioga. These results suggest that isolates from rice are phylogenetically close to those from Setaria species.
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  • Tomoki NISHINO, Seiko IMAIZUMI, Katsuhiro MIYABE, Masao YAMADA, Masao ...
    1995 Volume 61 Issue 6 Pages 555-561
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Annual bluegrass (Poa annua L.) samples were collected from several areas of Japan from 1991 to 1993. Eighty-nine isolates of Xanthomonas-like bacteria which caused wilting of annual bluegrass leaves upon artificial inoculation were isolated. Isolates were separated into two groups according to the pathogenicity demonstrated by leaf clipping inoculation. Ten isolates including JT-P482 as the representative isolate caused severe wilting of the whole plant, and 79 isolates including JT-P192 as the representative isolate caused mild wilt symptoms and/or pale-yellow discoloration limited to leaf blades. Pathogenicity and bacteriological properties of present isolates were compared with those of Xanthomonas campestris pv. graminis, X. c. pv. phlei, X. c. pv. arrhenatheri, X. c. pv. poae and X. c. pv. “poannua”. Regardless of differences in their pathogenicity, present isolates of both types were identified as X. c. pv. poae on the basis of host-specificity and bacteriological properties.
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  • Takashi KOBAYASHI, Tsutomu IJIRI, Twng Wah MEW, Gerard MANINGAS, Teruy ...
    1995 Volume 61 Issue 6 Pages 562-568
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A computerized forecasting system (BLIGHTASIRRI) was constructed to estimate the development of rice sheath blight disease and the yield loss associates with the disease in the Philippines. This system which describes disease development as vertical and horizontal development, was incorporated into all known data acquired from previous epidemiological studies. Vertical development expressed by the relative height of the uppermost lesions to the plant height was estimated on the basis of temperature, relative humidity and the susceptibility of rice sheath to the rice sheath blight fungus. On the other hand, horizontal development expressed by the percentage of diseased hills was determined from the combination of temperature, relative humidity and the number of sclerotia and tillers. Whole disease incidence was calculated from vertical and horizontal development by Hashiba's formula. Furthermore, to estimate the final yield loss, the relation between disease incidence and fully ripened kernels was analyzed. The model curve of vertical and horizontal development estimated by BLIGHTASIRRI was slightly different from actual development in paddy fields in the wet season of 1993 and 1994. Development of this system should enable to determine the need for fungicide application.
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  • Yafeng ZHU, Katsunori TAMURA, Minoru WATANABE, Izumi MATSUDA, Mamoru S ...
    1995 Volume 61 Issue 6 Pages 569-574
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Pseudomonas syringae pv. maculicola produces the chlorosis-inducing phytotoxin coronatine. The strain H3-6 isolated from Chinese cabbage harbored five indigenous plasmids. The strain H3-6 was treated with acridine orange (75 to 200ppm) and four coronatine-defective (Cor-) mutants were obtained. All Cor- mutants had lost the largest 83kb plasmid designated pMAC1. The presence of the region of cfl, one of coronatine-biosynthesis genes (Cor-genes) was determined by PCR amplification using cfl specific primers. An expected specific DNA of 0.65kb was amplified only in a plasmid DNA sample from the wild type, but not in any plasmids from Cor- mutants. Moreover, a similar PCR product was obtained in all plasmid DNA samples from three other Cor+ wild strains. A probe of the PCR product from H3-6 strain labeled with digoxigenin-dUTP hybridized to the largest plasmids including pMAC1 in all Cor+ wild strains, but did not hybridize to any other plasmids from tested bacterial strains including Cor- mutants. The 0.65-kb PCR product from H3-6 strains was cloned and sequenced. The PCR product contains almost identical DNA sequences to that of previously reported P. syringae pv. glycinea PG4180. These results reveal that the largest plasmids including pMAC1 of P. syringae pv. maculicola contain at least a part of Cor-genes (cfl) and probably a large region of clusters of Cor-genes. Thus, plasmid-mediated coronatine production in P. syringae pv. maculicola was indicated.
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  • Masamichi ISOGAI, Ichiro UYEDA, Ikuo KIMURA
    1995 Volume 61 Issue 6 Pages 575-577
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Toshiyuki MORIKAWA, Yoshikuni NOMURA, Takashi YAMAMOTO, Tomohide NATSU ...
    1995 Volume 61 Issue 6 Pages 578-581
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Motoichiro KODAMA, Kiyoshi INOUE, Hiroshi OTANI, Keisuke KOHMOTO
    1995 Volume 61 Issue 6 Pages 582-585
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Kunihei KISHI, Takao KOBAYASHI
    1995 Volume 61 Issue 6 Pages 586-589
    Published: December 25, 1995
    Released: February 19, 2009
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  • Masato IKEGAMI, Tsutou MORINAGA, Hiroyuki KAGAWA
    1995 Volume 61 Issue 6 Pages 590-592
    Published: December 25, 1995
    Released: February 19, 2009
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  • 1995 Volume 61 Issue 6 Pages 593-599
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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  • 1995 Volume 61 Issue 6 Pages 600-611
    Published: December 25, 1995
    Released: February 19, 2009
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  • 1995 Volume 61 Issue 6 Pages 612-636
    Published: December 25, 1995
    Released: February 19, 2009
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  • 1995 Volume 61 Issue 6 Pages 637-645
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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  • 1995 Volume 61 Issue 6 Pages 646-653
    Published: December 25, 1995
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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