Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Volume 58 , Issue 5
Showing 1-22 articles out of 22 articles from the selected issue
  • Henry NELSON, Seiji OUCHI, Tomonori SHIRAISHI, Hachiro OKU
    1992 Volume 58 Issue 5 Pages 659-663
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Fusarium wilt symptoms were reduced in tomato and cucumber plants when they were inoculated with Fusarium oxysporum f. sp. cucumerinum (non-pathogenic on tomato) and F. oxysporum f. sp. lycopersici (non-pathogenic on cucumber), respectively, prior to inoculation with the pathogenic formae speciales. The respective pathogenic forma specialis was isolated at a significantly high frequency from stem sections of symptomless plants which had been pre-inoculated with the respective non-pathogenic forma specialis or a mixture of the pathogenic and non-pathogenic formae speciales, but it was not isolated from symptomless plants which had been inoculated only with the pathogenic forma specialis. The respective non-pathogenic forma specialis was not isolated from stems of tomato or cucumber, irrespective of symptom development. The number of colony forming units per gram fresh weight of stem was less in pre-inoculated plants without symptoms than in pre-inoculated plants with symptoms. The reduction in symptoms observed in these plants following the induction of resistance by pre-inoculation with a non-pathogenic forma specialis may have been due to repressed proliferation of the pathogenic forma specialis.
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  • Leandro M. SANCHEZ, Yoshinori OHNO, Yoshio MIURA, Kazuhito KAWAKITA, N ...
    1992 Volume 58 Issue 5 Pages 664-670
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The suppressor action of water-soluble glucans (WSG) isolated from Phytophthora capsici, P. infestans and P. nicotianae var. nicotianae on hypersensitive cell death caused by elicitors was investigated using suspension-cultured of tomato (Lycopersicon esculentum Mill., L. peruvianum), sweet pepper (Capsicum frutescence L.) and tobacco (Nicotiana tabacum L.). The hypersensitive cell death was caused by elicitor of hyphal wall components (HWC) both from pathogenic and nonpathogenic Phytophthora spp. and depended on the concentration of the elicitor and duration of treatment. On the other hand, the WSG from respective species of Phytophthora suppressed the elicitor-induced cell death in the manner of host selectivity: the suppressor activity was specific only to its typical host (i.e., P. capsici for sweet pepper, P. infestans for tomato and P. nicotianae var. nicotianae for tobacco) and the common host (tomato). These results suggest that WSG from the above Phytophthora spp. may be involved in the determination of host-selectivity for the establishment of compatible interaction with their respective host plants.
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  • Hirosuke OGURA, Junrong MA
    1992 Volume 58 Issue 5 Pages 671-676
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    In the fields infested by cucumber wilt fusaria and cultured cucumber, soybean or sorghum for six years continuously, the persistence of the pathogen were observed. The pathogen survived in high population in cucumber and soybean fields, especially kept stable survival in the former field, but it population decreased at every cropping in sorghum field. Although the population decreased by crop conversion without regard to the kind of the crops, it turned to stable within one or two years. The fungus colonized at any time onto roots of cucumber from soil, but its colonization on soybean roots turned to be difficult with growth of the plant. The rhizosphere of sorghum offered uncomfortable condition for their colonization. There were many virulent strains for cucumber wilt from cucumber root colonizer. But many of the strains from other crop roots and field soils were in moderate or weak pathogenicities to cucumber. A lot of chlamydospore were formed by virulent strains in cucumber field and by weak strains in other two fields. It is considered that this characteristic and saprophytic or parasitic ability on root of each crop would send the pathogen toward dominant position in fusarial flora in each continuous cropping field.
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  • Tatsuji HATAYA, Katsuyuki HIKAGE, Narushi SUDA, Tatsuya NAGATA, Shifan ...
    1992 Volume 58 Issue 5 Pages 677-684
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A viroid-like RNA was detected in low molecular weight RNAs extracted from virus-free hops by two-dimensional polyacrylamide gel electrophoresis (PAGE). It migrated considerably faster than hop stunt viroid in 5% PAGE containing 8M urea under a denaturing condition. A cDNA fragment was amplified from the low molecular weight RNAs containing the viroid-like RNA by reverse transcription and polymerase chain reaction (RT-PCR) using a pair of hop latent viroid (HLVd) specific primers. The amplified cDNA product of expected size was detected by agarose gel electrophoresis. The full-length cDNA of the viroid-like RNA in RT-PCR products was cloned and sequenced. The established nucleotide sequence of the inserted cDNA was completely identical to that previously reported for HLVd. The total nucleic acids were extracted from hops cultivated in Japan, and the presence of HLVd were examined by dot blot hybridization and RT-PCR. In a hop sample, HLVd was not detected by dot blot hybridization, but detected by RT-PCR. The result indicates that RT-PCR is potentially more sensitive than dot blot hybridization using a radioactive probe. HLVd was detected in all mother cultivars tested. However, the two virus-free clones obtained by meristem culture showed negative reaction in both dot blot hybridization and RT-PCR detection methods. It is also shown that HLVd probably can be eliminated by meristem culture as indicated in several plant viruses and viroids
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  • Reiko SHIGEMOTO, Tetsuro OKUNO, Kazuho MATSUURA
    1992 Volume 58 Issue 5 Pages 685-690
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Trehalose was the main sugar accumulated in the mycelia of Rhizoctonia solani and the trehalose content was 8% and more in dry weight mycelia irrespective of the sugar sources used for incubation. The addition of validamycin A (VM-A), an inhibitor of trehalases, increased the trehalose content even more. The inhibition of growth of the mycelia of R. solani by VM-A occurred when the fungus was incubated in a medium containing trehalose as the sole carbon source but not when incubated in a medium containing various sugars and carbohydrate polymers. The results indicated that trehalose was used as a storage molecule to supply glucose required for growth of R. solani and that the anti-fungal activity of VM-A resulted from the anti-trehalase activity of the chemical.
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  • Hirotaka TAKANO, Satoru INOUE, Hiromichi OSHIO, Katsuzo KAMOSHITA, Kir ...
    1992 Volume 58 Issue 5 Pages 691-698
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The (R)-(-)-isomer of diniconazole showed strong antifungal activity against Gibberella fujikuroi in a liquid medium at more than 10-5M, whereas another isomer, (S)-(+) exhibited no effect on fungal growth even at 10-4M. Gas-liquid chromatographic analysis of sterols revealed that the (R)-(-)-isomer potently inhibited C-14 demethylation during ergosterol biosynthesis in G. fujikuroi at more than 10-6M. The (S)-(+)-isomer showed slight inhibition on it at more than 10-5M. Bioassay of gibberellins extracted from culture filtrates of G. fujikuroi with or without the fungicide revealed that the (R)-(-)-isomer almost completely inhibited a biosynthesis of gibberellins of the fungus at 10-5M and it was much stronger than that of the (S)-(+). Incorporation of 14C-mevalonic acid into fractions of gibberellin precursors revealed that the (R)-(-)-isomer inhibited the oxidation of ent-kaurene to ent-kaurenol during the gibberellin biosynthetic pathway of the fungus. These results indicated that the (R)-(-)-isomer of diniconazole is a strong inhibitor of both biosyntheses of ergosterol and gibberellins of G. fujikuroi compared with the (S)-(+).
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  • Ken SUZUKI, Eri MATSUMIYA, Yoshikazu UENO, Junya MIZUTANI
    1992 Volume 58 Issue 5 Pages 699-705
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A highly germinative resting spore specimen of Plasmodiophora brassicae was obtained through a preparation procedure which involved rotting clubroot galls prior to purification process using Ficoll-400 discontinuous density gradient centrifugation. More than 60% resting spores thus prepared germinated at maximum. By using this specimen, the existence of a germination-stimulating factor (GSF) in some plants' root exudates was verified. The GSF was not lost by autoclaving, removed easily by dialysis, adsorbed partially to XAD-4 resin, and not extractable with diethyl ether and ethyl acetate. The GSF was therefore presumed to be a heat stable, fairly polar and low molecular weight compound. Since the GSF was found not specifically in root exudate of a clubroot-susceptible crucifer but also in that of a resistant crucifer and lettuce, the GSF was considered to be a factor not relating to clubroot resistance and host recognition.
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  • Jun SHIMOYAMA, Mituro KAMEYA-IWAKI, Kaoru HANADA, Takashi GUNJI
    1992 Volume 58 Issue 5 Pages 706-712
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    In 1986, two potyviruses were detected from konjak plants (Amorphophallus konjac) showing mosaic symptoms in Gunma Prefecture, in Japan. One was identified as dasheen mosaic virus (DasMV), and the other was found different from DasMV in host range, symptom induction on Philodendron selloum, and serological properties. Out of 17 species in five families tested for susceptibility by sap inoculation, only three species in Araceae were infected by the virus, suggesting a narrow host range of the virus. The virus was infective when diluted up to 10-2 but not at 10-3, after heating for 10min at 55°C but not 60°C and storing for 2 days but not 4 days at room temperature. The virus was transmitted through corm of konjak and also by aphid, Aphis gossypi. Filamentous virus particles of about 800nm in length were detected in crude sap of infected P. selloum. The virus was serologically distinguished from DasMV, as far as investigated by double antibody sandwich-ELISA, immunodiffusion test and immunoelectron microscopy. The virus was concluded to be a new member of the potyvirus group, and was designated as konjak mosaic virus (KMV). KMV was detected from aroid plants, except Arisaema serratum and Colocasia esculenta, which were naturally infected.
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  • Jun SHIMOYAMA, Kaoru HANADA, Shinya TSUDA, Mituro KAMEYA-IWAKI, Takash ...
    1992 Volume 58 Issue 5 Pages 713-718
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The physicochemical and serological properties of konjak mosaic virus (KMV) and dasheen mosaic virus (DasMV) were studied. The molecular weight (MW) of nucleic acid of each virus was estimated to be 3.21×106 for KMV, and 3.42×106 for DasMV under denaturing conditions. While KMV had a single coat protein with MW of 35.5K, DasMV had two coat proteins with MWs of 32.5K and 40.0K. The 32.5K polypeptide was assumed to be derived from proteolytic degradation of the 40.0K protein, since both the proteins showed almost identical peptide patterns when analyzed by reverse phase high performance chromatography after treatment with Lysyl endopeptidase. ELISA showed that KMV was serologically related to soybean mosaic virus (SoyMV) and watermelon mosaic virus-2 (WMV-2) but unrelated to other six potyviruses including DasMV. Also, SoyMV and WMV-2 reacted with anti-KMV antibody by double immunodiffusion and western blotting analyses.
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  • Noemi P. OROLAZA, Kazuhito KAWAKITA, Noriyuki DOKE
    1992 Volume 58 Issue 5 Pages 719-725
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    AL-toxin, a host specific toxin produced by Alternaria alternata tomato pathotype, had been reported to cause accumulation of ethanolamine (EA) and phosphoethanolamine (PEA) in susceptible tomato leaves. In this connection, the effect of AL-toxin on the metabolism of phospholipids, particularly on the biosynthetic pathway of phosphatidylethanolamine (PtdEA) was investigated. [14C] EA was fed in leaf discs in both susceptible and resistant cultivars, Mie First and Saturn, respectively. The incorporation of [14C] EA into both tomato leaf discs similarly increased with incubation time, regardless of AL-toxin treatment, while significant inhibition of its incorporation into PtdEA was only found in susceptible leaf discs treated with the toxin. In a comparative study on the effect of AL-toxin on the biosynthesis of phosphatidylcholine (PtdC), the inhibition of incorporation of [14C] choline into PtdC in susceptible leaf discs was very low as compared to that of [14C] EA into PtdEA. Results from the present work indicate that AL-toxin have a greater inhibitory effect on the biosynthesis of PtdEA through EA in the leaves of susceptible cultivar, but not in resistant one.
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  • Tohru TERAOKA, Yoshinobu SHIMURA, Daijiroh HOSOKAWA, Minoru WATANABE
    1992 Volume 58 Issue 5 Pages 726-733
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Protoplasts of Pyricularia oryzae, which were isolated from mycelium or germ-tube by 1% Cellulase “Onozuka” R-10 and 1% Driselase, kept spherical shape and sensitivity to osmotic change, and became larger in size when incubated in potato sucrose broth or the synthetic medium containing 0.6M sucrose and also the enzymes. Twenty-four hr after incubation, more than half of the protoplasts became double or more in size. The formation of the giant protoplasts was inhibited by adding IBP or kasugamycin, but not by adding polyoxin D. The incubated protoplasts were fractionated to the giant-rich fraction and the original-size fraction by the two phase system with 0.6M mannitol and 0.6M sucrose. The giant protoplasts kept their viability as well as the original-size did, and had higher metabolic activity in all biosynthesis of protein, DNA, RNA, lipid and cell wall than the original-size had. These results suggest that this protoplast incubation system with the enzymes may be not so poisonous that the protoplasts could keep viability and grow without cell wall, and consequently become giant.
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  • Noriki HAYASHI, Mikihiro YAMAMOTO, Takashi TSUGE, Syoyo NISHIMURA
    1992 Volume 58 Issue 5 Pages 734-740
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Attempts were made to examine whether the strawberry pathotype of A. alternata could inhabit in the orchards of Japanese pear cv. Nijisseiki as a causal agent of black spot of the pear. First, black necrotic lesions that naturally occurred on Nijisseiki leaves were collected from the 3 pear orchards in Aichi Prefecture in 1983 and 1984. Field isolates from the 1219 lesions were assayed for their pathogenicity to leaves of Japanese pear and strawberry, but no isolate identified as the strawberry pathotype was detected. Secondly, the pathogen-free nursery plants of strawberry cv. Morioka-16, which were from the meristem-tip cultures, were transplanted in a Nijisseiki pear orchard as effective traps of air-borne spores of the strawberry pathotype during May, 1983 to September, 1984. From lesions that appeared on some leaves of the strawberry plants, an Alternaria fungus was isolated and identified as the strawberry pathotype, suggesting that the strawberry pathotype is inhabiting in Nijisseiki pear orchards at much lower density than the Japanese pear pathotype. In a simulation model experiment, parasitic fitness of the two pathotypes to the pear leaves was compared using highly virulent strains of the respective pathotypes. The results showed that the strawberry pathotype was inferior to the Japanese pear pathotype in parasitic fitness, judged by lesion number and lesion size, on the pear leaves under laboratory, phytotron and field conditions.
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  • Naoyuki MATSUMOTO, Akitoshi TAJIMI
    1992 Volume 58 Issue 5 Pages 741-751
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Low-temperature fungi were collected from plants just after snowmelt, and their antagonistic activity against Typhula ishikariensis, a snow mold fungus, was determined using orchardgrass seedlings. Isolates from gramineous plant debris, considered to beT. phacorrhiza, suppressed the disease caused by T. ishikariensis biotype A or B. Antagonists differed in their effectiveness against these biotypes. Isolates antagonistic to biotype A, which is the principal snow mold of perennial ryegrass in northern Hokkaido, were localized in this district. Despite prolonged snow, susceptible, perennial ryegrass is successfully grown there. These findings suggest the natural occurrence of biological control of the disease in perennial ryegrass pastures in northern Hokkaido. Ground tissues of orchardgrass or alfalfa reduced activities of antagonists when mixed in the inoculum. Plant litter such as fallen maple leaves and rice straw favored antagonism. Application of the antagonists in a naturally infested field planted with perennial ryegrass resulted in an yield increase of 26.5% compared with the untreated control where fall cutting favored the occurrence of snow mold. Where plants were not cut in fall and snow mold damage was slight, yield increase was insignificant.
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  • Takashi OKU, Tsuneo TSUCHIZAKI
    1992 Volume 58 Issue 5 Pages 752-756
    Published: December 25, 1992
    Released: February 19, 2009
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    Mobile nurseries were used to determine the virulence frequencies of wheat powdery mildew, Erysiphe graminis f. sp. tritici in fields. Test plants were exposed for 24hr in diseased wheat plots in Hokkaido, Tokyo and Okayama Prefectures in 1987-88. Nurseries consisted of eight lines with different resistance genes and a susceptible control line. Virulence was detected for all the eight genes tested: Pm1, Pm2, Pm3a, Pm3b, Pm4a, Pm5, a gene of Sapporo-haru-komugi (PmSh1) and Mli of cv, Ibis, but there were differences in frequency among regions. There was no clear relationship between previous use of a particular resistance gene and detected frequency of virulence to the gene. Mobile nursery method is a simple and efficient way to detect rare but dangerous races of virulent pathogens, and useful for finding important sources of resistance to powdery mildew. The method has considerable merit over conventional method in determining the variability and potential virulence of wheat powdery mildew. It should be helpful in similar studies with other air-borne plant pathogens.
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  • Akiko MURAYAMA, Ryoji AOSAKI, Masato IKEGAMI
    1992 Volume 58 Issue 5 Pages 757-760
    Published: December 25, 1992
    Released: February 19, 2009
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  • Hiroyuki SAWADA, Hiroshi OYAIZU, Satoshi MATSUMOTO, Hiroyuki IEKI
    1992 Volume 58 Issue 5 Pages 761-765
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Yukio HARADA, Seiko IMAIZUMI, Hiroshi TANAKA, Hideaki NEGISHI, Takane ...
    1992 Volume 58 Issue 5 Pages 766-768
    Published: December 25, 1992
    Released: February 19, 2009
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  • Yoshikuni NOMURA
    1992 Volume 58 Issue 5 Pages 769-772
    Published: December 25, 1992
    Released: February 19, 2009
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    Twenty-two isolates of the bottle gourd Fusarium wilt organism (Fusarium oxysporum f. sp. lagenariae) were collected from 22 regions of 8 prefectures in Japan and examined for their pathogenicity to pumpkins and bottle gourds. Some isolates had pathogenicity to Cucurbita ficifolia of a pumpkin plant, but some didn't. They were classified into 4 groups according to the pathogenicity decided on the basis of disease incidence days of the pumpkin; strong, moderate, weak and no pathogenicity. All of them had pathogenicity to bottle gourds, but had no pathogenicity to C. moschata and C. maxima×C. moschata.
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  • Daijiro HOSOKAWA, Kappei KOBAYASHI, Mamoru HORIKOSHI, Iwao FURUSAWA
    1992 Volume 58 Issue 5 Pages 773-779
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Seishi IKEDA, Hideyoshi TOYODA, Kenji YOSHIDA, Kazuharu KOREEDA, Kazuy ...
    1992 Volume 58 Issue 5 Pages 780-783
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Koji KAKUTANI, Hideyoshi TOYODA, Kazuhiko MATSUDA, Takatsugu NISHIDA, ...
    1992 Volume 58 Issue 5 Pages 784-788
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Shuu HASE, Akira KARASAWA, Hideki TAKAHASHI, Yoshio EHARA
    1992 Volume 58 Issue 5 Pages 789-793
    Published: December 25, 1992
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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