Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Volume 64 , Issue 6
Showing 1-15 articles out of 15 articles from the selected issue
  • Yasufumi HIKICHI, Kazumi SUZUKI, Kazuhiro TOYODA, Mamoru HORIKOSHI, Ta ...
    1998 Volume 64 Issue 6 Pages 519-525
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Pseudomonas cichorii SPC9001 was transformed with plasmid pNP126 containing luxCDABE operon of Vibrio fisheri, and bioluminescent IBRC82 was obtained. Growth and movement of IBRC82 and the response of host tissue were successively observed in the same lettuce leaf using the video-intensified microscopy (VIM) camera equipped with the ARGUS 50. Bacterial bioluminescence conferred by the lux operon was first observed at inoculated sites 2 days after inoculation and then in the surrounding region. It then moved along the leaf veins. Browning symptoms appeared in areas where bioluminescence had been detected and developed into bacterial rot. Microscopic observation showed that P. cichorii colonized the intercellular spaces of the epidermis and mesophyll and then moved into the vascular bundle. These results suggest that the disease symptom appears and develops, following the bacterial growth and movement in a lettuce leaf. In leaf disks infiltrated with the bioluminescent bacteria, bioluminescence was observed in the whole tissue 12hr after inoculation, and the disks then collapsed 36hr after inoculation. Cycloheximide, a eukaryote-specific protein synthesis inhibitor, completely suppressed the collapse of infiltrated disks, but had no effect on bacterial bioluminescence. These results demonstrate that the collapse of infiltrated disks following bacterial bioluminescence requires protein synthesis in the lettuce leaf. Therefore, the disease symptom appears and develops depending on the response of host tissues, including de novo protein synthesis, corresponding to the bacterial growth and movement in a lettuce leaf.
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  • Hiroshi TSUKAMOTO, Mitsuya TSUDA, Masatoshi GOHBARA, Takane FUJIMORI
    1998 Volume 64 Issue 6 Pages 526-531
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Factors affecting the herbicidal activity of Exserohilum monoceras JTB-808 against Echinochloa oryzicola young seedlings were examined using a drop inoculation method under greenhouse conditions. The herbicidal activity of the fungus correlated with water management practices. High herbicidal activity was produced by increasing the depth and duration of water flooding. When 105 conidia/100cm2 were introduced to a pot filled with water to a depth of 7cm or 9cm, more than 95% of plants were killed, and the dry weight of the plants was reduced by over 95% at 21 days after inoculation. A water depth of 7cm with 7 or more days of flooding gave almost the same results at 21 days after inoculation. When the flooding was prolonged to 14 days, the plants were completely destroyed. Shallow depths or short flooding duration were not effective. Lesion development under submergence was examined on the first leaf of E. oryzicola after inoculation with conidia embedded in low melting-temperature agarose gel. When inoculated leaves were kept under submergence for 1, 2 or 3 days, collapsed lesions enlarged to 14.3, 78.7 and 95.3% of the leaf area of each sample, respectively, by 10 days after inoculation. The results show that submergence of the host plants promoted lesion development, which led to high mycoherbicidal activity.
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  • Kenji NAKAHARA, Tatsuji HATAYA, Ichiro UYEDA, Hiroyuki IEKI
    1998 Volume 64 Issue 6 Pages 532-538
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    When detecting viroids in citrus tissues, contaminating polysaccharides and phenolic compounds often make it difficult to consistently extract nucleic acids. To extract the nucleic acids consistently, the method was improved as follows: the contaminants were removed by differential 2-butoxyethanol precipitation instead of a combination of 2-methoxyethanol extraction and cetyltrimethylammonium bromide precipitation. In contrast to the conventional method, the modified one consistently extracted some citrus viroids, i.e., citrus exocortis viroid (CEVd), group I citrus viroid (CVd-I) and hop stunt viroid-citrus isolate, which is a variant of group II citrus viroid (CVd-II), after they were sufficiently subjected to sequential polyacrylamide gel electrophoresis (sPAGE) and dot blot hybridization using digoxigenin (DIG)-labeled cRNA probes. A viroid-like RNA presumed to be a group III citrus viroid (CVd-III) was detected in nucleic acids extracted from Japanese citrus samples by sPAGE. The cDNA fragments of the viroid-like RNA were cloned and sequenced. The nucleotide sequences of the cDNAs were completely identical to those reported previously for CVd-IIIa and CVd-IIIb abroad. CVd-III was detected from several other Japanese citrus samples using the DIG-labeled cRNA probe prepared from the cloned cDNA. Many of these samples were also co-infected with other citrus viroids.
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  • Yoshihiro OHTSU, Kazuo NAKASHIMA, Maitree PROMMINTARA, Yuichi TOMIYASU
    1998 Volume 64 Issue 6 Pages 539-545
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Citrus greening disease caused by greening organisms (GOs; Liberobacter spp.) is one of the most destructive diseases of citrus in Nepal and Thailand. The 16S rDNA fragments of the GOs were detected by PCR in leaves showing one of the seven typical symptoms: mottling (type I), chlorosis with green netlike veins (type II), severe chlorosis with green main veins (type III), pale green on young leaves (type IV), vein yellowing (type V), vein corking (type VI) and yellow blotching (type VII). Leaves were collected from GO-infected ‘Suntala’ mandarin trees in Nepal. Sequence analysis of the 16S rDNA fragments and the 16S/23S intergenic spacer regions of Nepalese and Thai isolates of GOs indicated that these isolates were closely related to Indian and Chinese isolates of L. asiaticum. Symptom types III, V and VI were considered to be optimum for PCR diagnosis because of the high amount of GO DNA amplified. The accuracy of diagnosis by the naked eye can be improved by observing as many leaves as possible with all seven typical symptoms of greening on the same mandarin tree. Symptom types III, V and VII may be common to mandarin and sweet orange, because these symptoms are very similar to those reported on sweet orange in South Africa.
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  • S.M. Khorshed ALAM, Jiro TOGASHI, Tsuneo NAMAI, Koushi UEDA
    1998 Volume 64 Issue 6 Pages 546-551
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The role of the soft rot bacterium, Erwinia carotovora subsp. carotovora (Jones) Bergey et al., as a source of inoculum for soft rot of Chinese cabbage was examined by spraying a rifampicin-resistant strain (RRS) on spring and summer-sown Chinese cabbage (cv. Matsushima-kohai W-1116) leaves. The organism was then suspended in sterilized water at a concentration of 106cfu/ml and 2.0ml per plant was sprayed on the leaves at 20, 33, 47 and 60 days after seeding. In addition, 2.0ml/plant of the suspension at 108, 106, 104, 102 or 100cfu/ml were sprayed on the leaves at 45 days after seeding, respectively. The RRS sprayed on leaves of Chinese cabbage survived until harvest, but most of the plants were diseased, at 50-60 days after seeding both in the sprayed and control plants. Disease severity did not differ between the sprayed and control plants in the spring- and the summer-seeded crops except for the middle growing stage of the spring crop. The RRS from soft, rotten petioles and rhizosphere soil of diseased plants were reisolated by dilution plating onto modified Drigalski's medium containing rifampicin (RMDM). The RRS was predominantly reisolated from rotten tissues and rhizospheres of the diseased plants, irrespective of the spraying time and concentration of the used strain. Naturally occurring soft rot bacteria were detected on leaf surfaces of the plant at a population level of 105-106cfu/g of fresh tissue at 76 days after seeding in the spring crop and at 33 days after seeding in the summer crop. Soft rot bacteria artificially sprayed on leaves of Chinese cabbage survived until harvest and played a role as a source of inoculum for soft rot disease of Chinese cabbage in the field.
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  • Kimihiko KATO, Masatoshi ONUKI, Shinichi FUJI, Kaoru HANADA
    1998 Volume 64 Issue 6 Pages 552-559
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A new virus disease occurred in tomato in Shizuoka and Aichi prefectures. The virus from Shizuoka was transmitted by Bemisia tabaci of B biotype, but not by sap. Its narrow host range was restricted to five species from two families. Geminate particles were observed in partially purified virus preparation from infected leaves of Datura stramonium. Specific DNA bands were detected from infected plants by polymerase chain reaction using two sets of primers designed for DNA A component of geminiviruses. The viruses from Shizuoka and Aichi had extremely high degrees of nucleotide sequence similarities (98%) with a mild isolate of tomato yellow leaf curl virus from Israel (TYLCV-Is-M). Their genomic organization of DNA A was the same as that of TYLCV. The amino acid sequence similarity between six ORFs of TYLCV-Is-M and the equivalent ORFs of the virus isolates from Shizuoka and Aichi was over 95%. From these results, the two virus isolates were identified as TYLCV and were closely related to TYLCV-Is-M from Israel. This report is the first on the occurrence of TYLCV in tomato in Japan.
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  • Takumi MATSUMOTO, Satoshi T. OHKI
    1998 Volume 64 Issue 6 Pages 560-564
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Shigeo NAKAMURA, Takayoshi IWAI, Ryoso HONKURA
    1998 Volume 64 Issue 6 Pages 565-568
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Shoko ORIHARA, Takashi YAMAMOTO
    1998 Volume 64 Issue 6 Pages 569-573
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Hiroshi HAGIWARA, Kazuo ABIKO, Satoshi IZUTSU, Tokiya SHIMIZU, Hideki ...
    1998 Volume 64 Issue 6 Pages 575-578
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    In November 1997 powdery mildew of cyclamen was found in Nagano prefecture, Japan. White, powdery mycelial colonies appeared on petals. Artificial inoculation with the fungus was successful on cyclamen petals, but not on primula or begonia plants. Conidia were cylindric to doliform, 31-51×14-20μm, formed singly on conidiophores erected on aerial mycelium. Base of the conidiophores were almost straight but sometimes slightly curved. Lobed appressoria differentiated on germ tubes from conidia. No cleistothecium was observed. On the basis of the conidial stage, the fungus was identified as an Oidium sp. of the Erysiphe polygoni type.
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  • 1998 Volume 64 Issue 6 Pages 579-584
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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  • 1998 Volume 64 Issue 6 Pages 585-592
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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  • 1998 Volume 64 Issue 6 Pages 593-604
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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  • 1998 Volume 64 Issue 6 Pages 605-614
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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  • 1998 Volume 64 Issue 6 Pages 615-635
    Published: December 25, 1998
    Released: February 19, 2009
    JOURNALS FREE ACCESS
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