Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Volume 56 , Issue 1
Showing 1-18 articles out of 18 articles from the selected issue
  • Tsuneo NAMAI, Yoshio EHARA, Jiro TOGASHI
    1990 Volume 56 Issue 1 Pages 1-9
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    This paper deals with the changes in aggressiveness of the isolate belonging to race 337 of rice blast fungus, Pyricularia oryzae Cavara, which was re-isolated after successive passage on rice cultivars with a different single true resistance gene. An isolate (race 337) with wide spectrum of virulence was used as original inoculum for successive passage. The authors measured the rate of susceptible lesion per total lesions produced on a leaf blade and the number of conidia formed on a unit area of lesion (10mm2) on leaf of 4 rice cultivars possessing the same or different true resistance gene from that of passed cultivars as indicants for the aggressiveness. As the results, many isolates re-isolated after successive passage enhanced the aggressiveness to the rice cultivars with the same true resistance gene as that of passed cultivars. On the other hand, many isolates decreased the aggressiveness to the rice cultivars with different true resistance gene from that of passed cultivars.
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  • Isao MATSUMOTO, Yasuji ASADA
    1990 Volume 56 Issue 1 Pages 10-15
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Lignin formation in the Japanese radish root was not initiated by the lignification-inducing factor (LIF) alone but initiated with increase of L-phenylalanine ammonia-lyase (PAL) activity which was enhanced by the presence of ethylene released from 2-chloroethylphosphonic acid (CEPA). When cucumber leaves were treated with CEPA after the treatment with LIF obtained from the homogenate of diseased tissues, lignification of cell walls occurred immediately, and resistance against Colletotrichum lagenarium was induced in the leaf tissues. These results imply that the action of LIF was activated by the presence of ethylene and caused lignin induction, which resulted in the prevention of fungal development by the formation of lignified cell walls.
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  • Pyoyun PARK, Tohgo OHNO, Syoyo NISHIMURA, Kentaro TANABE, Keisuke KOHM ...
    1990 Volume 56 Issue 1 Pages 16-25
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Attempts were made to improve fixation and embedding methods for electron microscopy of Alternaria alternata spores. Among 16 methods tested, the ultrastructural images were greatly improved by the use of an en bloc alkaline bismuth stain or an osmium tetroxide-potassium ferrocyanide (reduced osmium) fixative. The cellular membranes were highly contrasted even in unstained sections obtained from en bloc alkaline bismuth-stained spores after prefixation in aldehyde and postfixation in potassium permanganate. The use of the reduced osmium, followed by en bloc uranyl acetate staining, resulted in fine and enhanced staining of cellular membranes after primary fixation of spores in aldehyde. An en bloc alkaline bismuth also selectively reacted with the cell wall and plasma membrane in aldehyde and osmium tetroxide-fixed spores. This indicates that the stain is useful for observation of cell wall and plasma membrane. Spores fixed with the reduced osmium always exhibited a poor infiltration of Spurr resin. This was considerably improved by placing the reduced osmium-fixed spores in a resin/propylene oxide mixture at 60C for 3hr, rinsing in propylene oxide, and performing the infiltration-process with prolonged exposure of the spores to resin.
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  • Tsuneo NAMAI, Tadahiro KATO, Yoshihiro YAMAGUCHI, Jiro TOGASHI
    1990 Volume 56 Issue 1 Pages 26-32
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    To reveal the relationship between the resistance to rice blast disease on rice plants and the amount of oxygenated C-18 unsaturated fatty acids isolated from rice plant as anti-blast substances, the change of the activity of lipoxygenase (LOX) which participates in the synthesis of these compounds in rice leaves was investigated. Although LOX activity in rice leaves was sensitive to the water-spraying resulted in a little increment, it has been clearly and largely enhanced by blast infection. The pattern of change in LOX activity with days after inoculation depended on the combination of rice cultivar and the race of rice blast fungus. In rice leaves shown incompatible reaction, LOX activity increased rapidly from the first day of spray-inoculation and reached to the maximum two or three days after, and declined thereafter. In the compatible combination, the highest activity was observed seven days after inoculation, although LOX activity rose temporarily in two or three days. Rice cultivars having higher level of field resistance showed higher LOX activity than that with low level of it. In addition, LOX activity in mature leaves was also greater than that of the just expanded young leaves of all cultivars examined.
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  • Wei Qin WANG, Tomohide NATSUAKI, Seiichi OKUDA, Michiaki TERANAKA
    1990 Volume 56 Issue 1 Pages 33-38
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Cucumber mosaic virus satellite RNA (CARNA5) was used to investigate the usefulness of replicative form double-stranded RNAs as nonradioactive photobiotin-labelled probes in hybridization studies. In dot-blot hybridization using purified dsCARNA5 labelled with photobiotin as the probe, as little as 2pg of dsCARNA5 was detected. The sensitivity for detecting dsCARNA5 was higher on nylon membranes than on nitrocellulose filters, and dot-blot hybridization was more sensitive than gel electrophoresis with silver staining. CARNA5 in partially purified total nucleic acids extracted from CMV-infected tobacco leaves was readily detected by dot-blot hybridization. Preparations from healthy leaves gave no hybridization signal. In this study three types of CARNA5 were detected and separated by electrophoresis. The three types of CARNA5 hybridized with each other, however, the strongest hybridization signal was obtained with the homologous type of CA-RNA5.
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  • Satomi HIRAI, Yoshimiki AMEMIYA
    1990 Volume 56 Issue 1 Pages 39-46
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    RNA profiles of cucumber mosaic virus (CMV) propagated in a resistant melon (Cucumis melo L. var. makuwa cv. Kohimeuri) and a susceptible melon (C. melo L. var. reticulatus cv. Earl's) were analyzed by 2.5% polyacrylamide gel electrophoresis. Relative amount of RNA 1 in RNAs of virus from Kohimeuri melon was markedly reduced in comparison with that from Earl's melon. Moreover, specific infectivity of virus particle and its total RNA from the former was less than that from the latter. Infectivity of total virus RNA from Kohimeuri, however, increased by addition of RNA 1 separated from original CMV. When leaves of Xanthi-nc tobacco were inoculated with virus from Kohimeuri or Earl's melons, the pattern of virus multiplication, symptom expression and RNA profiles in the progeny virus in the leaves were similar each other. When CMV-inoculated Kohimeuri leaves were treated with actinomycin D (10μg/ml), the virus multiplication was stimulated and the deficiency of RNA 1 in the multiplied virus did not occur. These results suggest that the unbalanced synthesis of CMV-RNAs (deficiency of RNA 1) is related to the resistance mechanism of Kohimeuri melon to CMV.
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  • Fumiyoshi FUKUMOTO, Hiroshi TOCHIHARA
    1990 Volume 56 Issue 1 Pages 47-55
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The infectivity of purified southern bean mosaic virus (SBMV) in 10mM sodium phosphate buffer, pH 7.0, decreased to 11% after freeze-drying. Such partially swollen virions were found to be markedly susceptible to RNase and sodium dodecyl sulfate (SDS). However, in the preparations supplemented with 0.5% lysine prior to freeze-drying the conformational changes of the virions were suppressed and the effect of RNase and SDS was well tolerated. On the other hand, there were little differences in infectivity of extracted RNA from virions between the preparations with or without lysine. It was suggested that the alterations of the conformation of the SBMV virions caused mainly the decrease of the infectivity of the virus preparations. During storage at 65C, the preparations of freeze-dried viruses lost their infectivity within one day and all the virions became markedly swollen. RNA extracted from such virions was degraded completely and did not display any infectivity. On the other hand, the virions of the preparations supplemented with 0.5% lysine retained their conformation and a high level of infectivity was maintained in both the preparations of virions and RNA extracted from the virions compared with the preparations without any additives. In the freeze-dried preparations of SBMV-RNA, lysine showed a protective effect during storage. Freeze-dried preparations of carnation mottle virus during storage at 65C showed a response similar to that of SBMV.
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  • Hai Ru CHEN, Daijiro HOSOKAWA, Minoru WATANABE
    1990 Volume 56 Issue 1 Pages 56-62
    Published: January 25, 1990
    Released: February 19, 2009
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    The growth curve of tobacco mosaic virus (TMV) in inoculated leaves of tobacco cv. Ambalema was far low compared to that of susceptible cv. Xanthi. The virus concentration in Ambalema leaves at 12 days after inoculation is one-eighth or less of the level attained in Xanthi leaves. The amount of TMV in Ambalema leaves increased 2.5- to 3-fold when actinomycin D was applied immediately or 1 day after inoculation, but not increased by the application at 10 days or later after inoculation, suggesting that the virus resistance of Ambalema may depend on transcription from host DNA. Ambalema protoplasts isolated from the inoculated leaves at various time showed a steady increase in the fraction of infected cells (as judged by TMV-specific fluorescent antibody staining) to a value of approximately 31.5% at 15 days after inoculation, but in the protoplasts from Xanthi, the fraction of infected cells rapidly increased to value of approximately 80% at 7 days after inoculation and remain close to that value thereafter. In this case, the level of virus accumulation per infected protoplast of Ambalema was far less than that of Xanthi. When these protoplasts were incubated for 72hr, the level of virus accumulation per infected protoplast increased 3.4- to 5.0-fold in Ambalema and 1.7- to 2.1-fold in Xanthi. The increase of the fraction of infected protoplasts and the amounts of virus were observed in protoplasts isolated from the leaves which virus multiplication were increased by treatment with actinomycin D. When protoplasts isolated from healthy leaves were infected with TMV, protoplasts from Ambalema had a percentage of infection similar to and supported a slightly lower accumulation of virus than Xanthi protoplasts. Actinomycin D did not effect the multiplication of TMV in the protoplasts isolated from both tobacco cultivars. It was concluded that the resistance of Ambalema tobacco to infection by TMV involves the reduced accumulation in cell and spread of the virus in host tissues, but this ability to reduce virus accumulation were not formed in protoplasts.
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  • Masuhiro ISHIMOTO, Yoshitaka SANO, Makoto KOJIMA
    1990 Volume 56 Issue 1 Pages 63-72
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    In Japanese radish plants infected with both cucumber mosaic virus (CMV) and turnip mosaic virus (TuMV), the concentration of CMV was significantly higher than in plants inoculated only with CMV. The distribution of viruses or viral antigens in inoculated plants was examined by electron microscopy and enzyme-immunohistochemistry. These observations indicated that the increase of CMV concentration was mainly due to an increase in the number of CMV-infected cells. Co-infection with TuMV had little effect on the cell-to-cell transport of CMV but significantly enhanced the long-distance transport of this virus.
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  • Nobuya TASHIRO, Kiyotaka MIYASHITA, Takahito SUZUI
    1990 Volume 56 Issue 1 Pages 73-82
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Taxonomic studies were made on Streptomyces species, causal organisms of potato common scab, isolated from lesions of potato tubers and sugar beet roots in Japan. They were divided into two groups based on the spore chain morphology: spiral spore chain isolates (SI) group and rectiflexible spore chain isolates (RFI) one. Although the two groups did not significanlty differ each other in their physiological and biochemical characteristics, DNA homology study further divided them into four distinct groups: SI from potato, RFI from potato, SI from sugar beet, and RFI from sugar beet. Because of the low DNA homology values among the four groups, they should be considered as separate species. Present study confirm that the potato common scab is caused by at least four genetically distinct species of Streptomyces.
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  • Tokuji KAGIWATA, Keiko T. NATSUAKI, Hiroshi FUJII, Hideo MUKOO
    1990 Volume 56 Issue 1 Pages 83-87
    Published: January 25, 1990
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Pseudomonas syringae pv. syringae isolated from lilac was inoculated to 133 species of economic woody plants and the symptoms of each plant were surveyed. Severe necrotic symptoms were formed on twigs or leaves of 36 species. The symptoms with extended necrosis were observed on 38 species and stationary necrotic spots on 57 species. No symptom occurred on 2 species. The early defoliation occurred on 26 species. From these results, the parasitism of the present bacterium was recognized on 74 species.
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  • Tsuneo WATANABE
    1990 Volume 56 Issue 1 Pages 88-91
    Published: January 25, 1990
    Released: February 19, 2009
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  • 1990 Volume 56 Issue 1 Pages 92-102
    Published: January 25, 1990
    Released: February 19, 2009
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  • 1990 Volume 56 Issue 1 Pages 103-109
    Published: January 25, 1990
    Released: February 19, 2009
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  • 1990 Volume 56 Issue 1 Pages 110-115
    Published: January 25, 1990
    Released: February 19, 2009
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  • 1990 Volume 56 Issue 1 Pages 116-136
    Published: January 25, 1990
    Released: February 19, 2009
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  • 1990 Volume 56 Issue 1 Pages 137-145
    Published: January 25, 1990
    Released: February 19, 2009
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  • 1990 Volume 56 Issue 1 Pages 146-157
    Published: January 25, 1990
    Released: February 19, 2009
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