Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Volume 52 , Issue 1
Showing 1-19 articles out of 19 articles from the selected issue
  • Shinichi KUSAKARI, Yutaka TANAKA
    1986 Volume 52 Issue 1 Pages 1-7
    Published: January 25, 1986
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    In hydroponics, the damping-off of spinach seedling by Pythium butleri was remarkably suppressed by highly concertrated nutrient solution (2-fold or 3-fold of standard solution). Zoospores of P. butleri encysted within a few minutes in highly concentrated nutrient solution, and they could not attach to the root surface of spinach. The zoospore encystment also occurred in the solutions of 0.02M each of calcium nitrate and calcium chloride, 0.05M of magnesium sulphate. and 0.2M each of mannitol, glucose and sucrose. These results indicated that the suppression of the damping-off in high concentration of nutrient solution was due to zoospore encystment induced by osmotic pressure of the nutrient solution.
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  • Masaki YAMAMOTO, Tsuneyoshi KUROIWA
    1986 Volume 52 Issue 1 Pages 8-14
    Published: January 25, 1986
    Released: February 19, 2009
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    Hypersensitive flecks were induced by a compatible race of Phytophthora infestestans on the leaves of potato cultivar Irish Cobbler (gene r) which had been rubbed with nuclear DNA from a resistant hybrid (cv. Greta, R1R3R4 genes) prior to inoculation. The hybrid nuclear DNA combined with propidiumiodide (PI) or 4'-6-diamidinophenylindole (DAPI) was taken up into potato cell nuclei 1 hr after rubbing on the epidermis, while chloroplast DNA was not incorporated into nuclei. DNA of molecular weight range 1, 750-2, 550kd separated by electrophoresis had ability to induce fleck formation. In order to know the size of DNA required for inducing fleck response against compatible race DNA was treated with restriction enzymes, EcoRI, SalI and/or KpnI. The EcoRI-SalI-treated DNA induced hypersensitive flecks and the EcoRI-KpnI-treated one did not.
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  • Kei OGAWA, Hajimu KOMADA
    1986 Volume 52 Issue 1 Pages 15-21
    Published: January 25, 1986
    Released: February 19, 2009
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    No antibiosis was observed in confronting plate culture between nonpathogenic Fusarium oxysporum, cross-protection agent, and F. oxysporum f. sp. batatas, pathogen of Fusarium wilt of sweet potato. Only pre-inoculation with live bud-cells of the agent brought about cross-protection. Neither paraffin plugging of the cut-ends of sweet potato sprouts nor dipping the cut-ends into heat- or ethanol-killed bud-cells of the agent caused any decrease of the disease incidence. Both natural infection and artificial inoculation with the pathogen at the distant portion on the sprout from the pre-inoculated cut-ends, brought about decrease of the disease incidence, suggesting induction of systemic resistance. Simultaneous inoculation with both the pathogen and agent also caused cross-protection. The agent previously inoculated existed at the cut-ends but little growth upwards through the vessels was observed. It multiplied locally in the cortex and parenchyma tissues at the cut-ends caused local le-sions. Excision of the cut-ends immediately after pre-inoculation with the agent nullified the cross-protective effect but excision at two days after the treatment did not. The filtrate of germinated bud-cell suspension of the agent brought about little decrease of the disease incidence. Thus, induction of systemic resistance in this cross-protection phenomenon is assumed to be caused by a slight and local infection with the agent previously inoculated at the cut-ends.
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  • Pissawan POOLPOL, Tadao INOUYE
    1986 Volume 52 Issue 1 Pages 22-30
    Published: January 25, 1986
    Released: February 19, 2009
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    Cucumber mosaic virus (CMV) and zucchini yellow mosaic virus (ZYMV) simultaneously inoculated on cucumber plants caused severer symptoms than those produced by CMV single infection, whilst weakened the symptoms caused by ZYMV. Determination of CMV concentration by infectivity assay indicated that concentration of CMV in doubly infected plants was higher than those in singly infected plants. On the contrary, ZYMV concentration significantly decreased after mixed infection as determined by enzyme-linked immunosorbent assay. Yields of CMV obtained by sucrose density gradient centrifugation from doubly infected cucumber plants were distinctly higher than those from singly infected ones about 3 weeks after inoculation. The enhanced multiplication of CMV was also found in doubly infected plants whether CMV was inoculated 1 or 2 weeks before or after ZYMV inoculation. Electron microscopy of doubly infected leaf cells revealed abundant masses of CMV aggregates in the cytoplasm. Examination of CMV infected protoplasts prepared from singly and doubly infected cucumber leaves suggested that higher concentration of CMV in double infection was due not only to the increase of CMV quantity in individual cells, but also to the increase in proportion of CMV infected cells.
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  • Hirokatsu UCHINO, Katsuichi KANZAWA, Tadao UI
    1986 Volume 52 Issue 1 Pages 31-38
    Published: January 25, 1986
    Released: February 19, 2009
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    A new leaf spot of sugar beet was detected in Tokoro-cho, Hokkaido in late July 1974. The disease was restricted to the sugar beet plants adjacent to garlic fields where garlic tip blight occurred severely. The causal fungus was identified as Pleospora herbarum (Fries) Rabenhorst (anamorph: Stemphylium botryosum Wallroth), and the name of “Stemphylium leaf snot” of sugar beet was proposed for this disease.
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  • Yutaka ARIMOTO, Yasuo HOMMA, Tomomasa MISATO
    1986 Volume 52 Issue 1 Pages 39-46
    Published: January 25, 1986
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A series of experiments were conducted to clarify the reason why the invading hyphae of Diaporthe citri (Faw.) Wolf is arrested and killed in melanose spot. After a melanose spot on citrus leaf was formed, pycnospore suspension of D. citri with 2% fructose was inoculated onto the melanose spot. The pycnospore germination was markedly inhibited and the germination rate was only 7%. On the healthy part of the leaf, the germination rate was 98%. The extract of melanose spot inhibited the pycnospore germination of D. citri. An antifungal substance was isolated from the extract of melanose spots by the chromatography on silica gel G layer. It was then crystallized from acetone-water, and needle-like crystal was obtained and named inhibitor D. Inhibitor D was not detected on the chromatogram of the extract of uninfected leaves and peels of citrus plant. It means that inhibitor D was produced in the plant post infectionally, and may be a phytoalexin. The extract of uninfected leaf also inhibited the pycnospore germination of D. citri. It seems that the inhibitory effect of the extract of uninfected leaf is caused by the action of pre-inhibitins such as citrinol, naringin and hesperidin in the uninfected tissues of citrus plant. These results explain the reason why the invading hyphae of D. citri into the citrus leaf and peel was arrested and then killed; namely, it is due to the antifungal action of pre-inhibitins and the phytoalexin-like substance. Therefore, this phenomenon seems to be a chemical defense reaction in citrus plant against invasion of pathogenic fungus. The phytoalexinlike substance was also detected from scab spot, canker spot, star melanose and oleocellosis on citrus fruits.
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  • Kenji KOIKE, Akio KOJIMA, Teruyoshi HASHIBA
    1986 Volume 52 Issue 1 Pages 47-52
    Published: January 25, 1986
    Released: February 19, 2009
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    The sample size needed to investigate the disease incidence of rice sheath blight disease was studied by using the relative height of the uppermost lesion to the plant height and the percentage of hills affected by the rice sheath blight disease, which were obtained in 3 fields with different degrees of incidence and 30 fields sampled randomly from an area of 1, 500 ha at Kubiki-mura, Niigata Prefecture from 1981 to 1983. The sample size (n) required was estimated from fluctuation of the confidence limits for the mean of relative height of the uppermost lesions to plant height, and from the Snedecor & Cochran's formula, n=t2σ2/L2 with allowable error (L) limited within±15% of the mean. The sample size required to estimate the percentage of affected hills and the relative height of the uppermost lesions to plant height in a single field were 10 and 100 hills, respectively. Twenty fields were required to estimate disease incidence of rice sheath blight disease in the area of 1, 500 ha. The sample of single hill was selected at random from A, B, C, D and E rows, and picked every fifteenth hill thereafter. The 20 hills were drawn from each row. This systematic sampling was the most efficient sampling method to investigate the rice sheath blight disease.
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  • Motohiro HIRAMATSU, Yuki ICHINOSE, Tomonori SHIRAISHI, Hachiro OKU, Se ...
    1986 Volume 52 Issue 1 Pages 53-58
    Published: January 25, 1986
    Released: February 19, 2009
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    Regulation of pisatin biosynthesis in naked mesophyll tissue of pea leaves by suppressor (F5) and elicitor isolated from Mycosphaerella pinodes was studied using a radioactive precursor of pisatin synthesis, 14C-phenylalanine. Incorporation of radioactivity became detectable 4.5-6 hr after elicitor treatment and increased thereafter. Concomitant presence of F5 inhibited the pisatin inducing activity of the elicitor completely. Treatment of pea leaves with F5 after elicitor-activation caused a reduction of pisatin synthesis and an increased accumulation of cinnamic acid, an intermediate of pisatin synthesis. F5 was found to inhibit in vitro the activity of phenylalanine ammonia-lyase and cinnamate 4-hydroxylase. The suppressing ability of F5 on pisatin synthesis seemed to be reversible.
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  • Masao GOTO, Kunihiko MATSUMOTO
    1986 Volume 52 Issue 1 Pages 59-68
    Published: January 25, 1986
    Released: February 19, 2009
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    Phoma sp., Erwinia and Pseudomonas soft rot bacteria, and a coryneform bacterium were isolated from rhizomes of wasabi (Eutrema wasabi Maxim.) with the internal black rot syndrome. These pathogens were also isolated in fibrous roots with black necrotic steles which are commonly found on the rhizomes with or without the internal black rot syndrome. The isolation frequencies of these pathogens were significantly different depending on various factors such as growing seasons, localities, or mountain streams in which the wasabi fields are laid. The cultures of Phoma sp. were identified as P. wasabiae Yokogi, the causal agent of black leg disease, on the basis of morphological and pathological characteristics. Soft rot bacteria were isolated in association with saprophytic bacteria at a significantly low level from the tissues of rhizomes and roots which seldom exhibited soft rot symptoms. They were sometimes isolated in association with Phoma wasabiae. Soft rot bacteria showed distinct seasonal alternation, erwinias being prevalent in summer and pseudomonads in winter. Soft rot erwinias and pseudomonads were isolated from water flowing on crop beds or in drainage canal. Soft rot pseudomonads were also isolated from water flowing out of a spring. A coryneform bacterium showed a very high population in the diseased tissues so that it grew singly on the isolation plates. In some rhizomes and fibrous roots with the same syndrome, no microorganisms but some saprophytic bacteria were isolated, suggesting that the disorder may also be caused by factors other than microbial infection.
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  • Masao GOTO, Kunihiko MATSUMOTO
    1986 Volume 52 Issue 1 Pages 69-77
    Published: January 25, 1986
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Various kinds of soft rot bacteria were isolated from rhizomes of wasabi or Japanese horse radish (Eutrema wasabi Maxim.) with the internal black rot syndrome as well as from fibrous roots showing black stele symptoms. These bacteria included Erwinia spp. and Pseudomonas spp. Based on the bacteriological characteristics, Erwinia soft rot bacteria were divided into 4 groups. The strains of group 1 were identified as E. rhapontici which failed to produce pink diffusible pigment on any kinds of media used in the study. The strains of group 4 were identified as E. carotovora subsp. carotovora. The strains of group 3 were also identical with subsp. carotovora although they differed from the former in a few phenotypic characters. The strains of group 2 differed from subsp. carotovora in properties such as delayed acid production from lactose, absence of β-galactosidase, inability to utilize melibiose and raffinose, absence of growth in KCN broth, in 5% NaCl broth and at 36 C. This group should be classified as a new taxon in the genus Erwinia. Pseudomonas soft rot bacteria were divided into 5 groups by the bacteriological tests. The strains of groups 1, 2, and 5 were identified as P. marginalis (=biovar II of P. fluorescens) based on their overall similarity of phenotypic characteristics. The strains of group 4 were identified as P. viridiflava although they differed from the description of the bacterium in the literature in some minor characters. The strains of group 3 were also identical to P. viridiflava in the characteristics of the LOPAT test. However, the physiological and biochemical properties were significantly different from those of any of the soft rot pseudomonads hitherto described. Therefore, the taxonomic attributes of this group remain to be determined by more detailed comparative studies in future.
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  • Kaoru OHMORI, Yutaka WATANABE
    1986 Volume 52 Issue 1 Pages 78-81
    Published: January 25, 1986
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A new soil fungicide, methasulfocarb [S-(4-methylsulfonyloxyphenyl) N-methylthiocarbamate, Kayabest®, NK-191] 10% dust was good for control of bacterial seedling rot of rice caused by Pseudomonas glumae Kurita et Tabei. Better control effect was obtained when the air temperature was suitable for rice seedlings during the nursery period or when inoculum concentration was low. The soil application procedure was the same as that for control of the seedling blight of rice plant caused by several different pathogens.
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  • Susumu TAKAMATSU, Takio ICHITANI
    1986 Volume 52 Issue 1 Pages 82-85
    Published: January 25, 1986
    Released: February 19, 2009
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  • Yuzo NOZU, Tomio USUGI, Kei NISHIMORI
    1986 Volume 52 Issue 1 Pages 86-89
    Published: January 25, 1986
    Released: February 19, 2009
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  • 1986 Volume 52 Issue 1 Pages 90-103
    Published: January 25, 1986
    Released: February 19, 2009
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  • 1986 Volume 52 Issue 1 Pages 104-111
    Published: January 25, 1986
    Released: February 19, 2009
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  • 1986 Volume 52 Issue 1 Pages 112-120
    Published: January 25, 1986
    Released: February 19, 2009
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  • 1986 Volume 52 Issue 1 Pages 121-136
    Published: January 25, 1986
    Released: February 19, 2009
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  • 1986 Volume 52 Issue 1 Pages 137-144
    Published: January 25, 1986
    Released: February 19, 2009
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  • 1986 Volume 52 Issue 1 Pages 145-154
    Published: January 25, 1986
    Released: February 19, 2009
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