Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Volume 43 , Issue 5
Showing 1-16 articles out of 16 articles from the selected issue
  • Ryozo YOKOSAWA, Shiro KUNINAGA
    1977 Volume 43 Issue 5 Pages 501-507
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The longevity and infectivity of zoospores of Aphanomyces euteiches and A. cochlioides in soil were studied. The motility of most zoospores was lost in soil within a day, but a small number of them kept for 5 days. The most of zoospores incubated in unsterilized soil disappeared within 5 days, but under low temperatures such as 13C to 20C, a small number of them still remained and kept germinability for 24 days. Zoospores of both fungi kept their infectivity in unsterilized soil for 20 or 30 days. Fifty zoospores per gram of soil were enough to cause damping off of the respective host plant seedling. The maximum zoospore production of A. euteiches per infected seedling attained 9×104 at 75-90% of maximum water-holding capacity of soil and 1.8×105 at 50-60%. Zoospores of A. euteiches and A. cochlioides which are produced on the infected plants survive for 3 to 4 weeks in soil, and surve as inocula of subsequent infections.
    Download PDF (1091K)
  • Shigehisa KIYOSAWA, Hiroyuki YASUDA, Isao SHINTANI
    1977 Volume 43 Issue 5 Pages 508-516
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Twelve rice varieties with and without a blast resistance gene, Pi-z, were tested for their field resistance in a paddy field in Takayama, Gifu Prefecture. It was attempted to evaluate the field resistance by estimating infection rate on each variety. A negative correlation was obtained between the number of lesions per plant, y, and the infection rate, r, calculated by the equation, r=(lny2-lny1)/(t2-t1), where y2 and y1 were the number of lesions at times t2 and t1, respectively. Taking this fact into consideration, corrected equations were proposed to estimate the infection rate: r=[ln{y2/(Y-y2)}-ln{y1/(Y-y1)}]/(t2-t1), and Y=y1/x1, where x1 was the proportion of diseased leaf-area at t1, and t2-t1 was the incubation period.
    Download PDF (874K)
  • Shigehisa KIYOSAWA, Hiroyuki YASUDA, Isao SHINTANI, Hitoshi KOIDE, Tak ...
    1977 Volume 43 Issue 5 Pages 517-523
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Eleven rice varieties with and without a resistance gene, Pi-z, were tested for their blast resistance in two blast nurseries in Takayama, Gifu Prefecture and Inabu, Aichi Prefecture. Disease severity was measured mainly by the number of lesions per plant and the proportion of diseased leaf-area in Takayama and Inabu, respectively. In both cases, field susceptibility was evaluated by estimating the infection rate on each variety. Infection rate was calculated by various methods. A significant varietal difference of infection rates was obtained in an experiment with three or four replications. The highest correlation coefficient between infecton rates of two nursery tests and that between those of the nursery tests and the field test in the previous paper were obtained when the infection rate was calculated using the equation, rx=(lnX2/1-x2-lnx1/1-x1)/(t2-t1). A low correlation coefficient was obtained between infection rates measured at different periods, indicating the importance of choice of dates for rating.
    Download PDF (652K)
  • Fumio OKADA
    1977 Volume 43 Issue 5 Pages 524-527
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Tea leaf galloyl - catechins, (-) -epicatechin gallate ((-) ECg) and (-) -epigallocatechin gallate ((-) EGCg) inhibited local lesion formation by tobacco mosaic virus (TMV) on Nicotiana glutinosa. In the present report, the amount of catechins necessary for inhibiting TMV infectivity and recovery of the infectivity after catechin removal by gelatin were investigated. When 0.1 and 0.2% (w/v) of (-) ECg were added to TMV solution (ca. 32μg/ml), the inhibition was estimated to be 90 and 99%, respectively. The same concentrations of (-) EGCg inhibited by 98 and 99%, respectively. When a definite concentration of gelatin was added to the mixture of (-) ECg and infected tobacco leaf extract, the number of local lesions increased as the period of incubation was prolonged. The addition of gelatin, however, did not cause any change in the inhibitory activity of (-) EGCg even after aprolonged incubation. The mode of inhibition by catechin of the local lesion formation was discussed in connection with the action of tannic acid.
    Download PDF (365K)
  • Tokuzo HIRAI, Toru TAKII, Kiyonori TAKII, Fukumi GOGA
    1977 Volume 43 Issue 5 Pages 528-536
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    An antibiotic, chromomycin A3 (CMA) which was isolated in Japan and has been known to inhibit DNA dependent RNA synthesis as actinomycin D (AMD) does, and tobacco mosaic virus (TMV) protein obtained by the acetic acid method were introduced through the roots or stems into tomato cultivars susceptible or resistant to TMV. TMV concentration in tomato leaves was determined by measuring OD260 of the resultant virus nucleoprotein that was precipitated by adding 0.25 saturated ammonium sulfate to the extract clarified by chloroform. Introduction of 5-30ppm of CMA for 7 days following TMV inoculation reduced the virus concentration in leaves of resistant cultivars as compared with those in untreated plants, but did not in the susceptible cultivar. Ten ppm of CMA introduced into the resistant cultivar for 1 day following inoculation was proved sufficient to induce resistance. By introducing 2-17μg of TMV protein into tomato plants through the roots or stems, TMV concentration in both susceptible and resistant cultivars was reduced below that in untreated plants, suggesting that TMV protein induced resistance. Polyacrylamide gel electrophoresis and isoelectric focusing for peroxidase (PO) isoenzymes revealed that, in the susceptible cultivar treated with CMA, number of bands in the gel and PO activity of each band decreased as compared with untreated control, while the resistant cultivar showed an increased PO activity. Introduction through the stems of TMV protein caused an increase in the activity of PO isoenzymes in both the susceptible and resistant cultivars. Especially, II group of isoenzymes which has an isoelectric point at pH 6.0 was increased in its intensity by TMV protein treatment. Based on these facts obtained, efficient inducers for resistance against virus in tomato cultivars and the relation between the induction of resistance and PO activity are discussed.
    Download PDF (970K)
  • Katsumi AKUTSU, Koji AMANO, Kiyoshi YORA
    1977 Volume 43 Issue 5 Pages 537-548
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Effects of L-methionine on the barley powdery mildew (Erysiphe graminis f. sp. hordei) were studied by electron microscopy. Barley leaves were treated with L-methionine (8×10-3M aqueous solution) 24hr before inoculation with the fungus. Primary haustoria formed in the treated leaves were examined under an electron microscope 24, 58, 96 and 168hr after inoculation. At early stages of infection, no degeneration was observed in the cytoplasm of the haustoria. Their sheath membranes were covered with electron-dense materials and their sheath matrix also contained electron-dense materials different from the former. At later stages, the haustorial content increased in electron-density, and large, more densely stained deposits were found in the cytoplasm. Epidermal cells of barley leaves treated with L-methionine before inoculation with the fungus usually became necrotic, accumulating electron -dense granules in the vacuoles. Since this phenomenon has been observed in leaves of barley varieties resistant to the barley powdery mildew, the inhibitory action of L-methionine on the fungus is thought to be due to the induction of resist ant reaction in barley leaves by L-methionine treatment. In hyphae of the fungus on barley leaves treated with L-methionine, degeneration of cell organelles could not be found, but large vacuoles with electron-dense deposits could. When barley leaves were inoculated with the fungus and treated with L-methionine 96hr after inoculation, abnormal conidia showing different stages of degeneration (partial expansion of cell wall, aggregation of the cytoplasm, and disappearance of the aggregated materials) were collected 72hr after treatment.
    Download PDF (4385K)
  • Takuji KOZAKA, Toru TERAOKA
    1977 Volume 43 Issue 5 Pages 549-556
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The rice plants treated with pulp-masses containing ethrel at more than 30ppm by spotting on leaves showed symptoms quite similar to the stunting of blast diseased plants, i.e., shortened new leaf blades and sheaths that emerged after infection, hastened leaf emergence period and epinasty of infected leaves. The ethylene evolution in susceptible cultivar inoculated with the blast fungus occurred immediately after infection and increased considerably toward eleventh day reaching the maximum level of 2.7nl/g/h, but decreased rapidly thereafter. Stunting of the plants was also induced as early as the latent period, becoming more conspicuous with disease development. In resistant cultivar the temporal evolution could be detected only two days after inoculation, resulting in no stunting. The leaves bearing acute type lesions with waterly greenish grey color produced much more ethylene than those with chronic type lesions with grey center and brown margin. There was no significant difference in the amounts of ethylene during the first 14 days that required for 1% inhibition of plant growth between the infected and the ethrel-treated plants. These facts suggest that ethylene may be a major factor for stunting of blast infected rice plants.
    Download PDF (885K)
  • Hideo ISHII, Akira YAMAGUCHI
    1977 Volume 43 Issue 5 Pages 557-561
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    In 1975, spray applications of thiophanate-methyl and benomyl failed to control scab in several Japanese pear orchards. Mycelia of Venturia nashicola isolates, obtained from these orchards, developed normally on PDA supplemented with 50-800ppm of thiophanate-methyl or benomyl. Sensitive isolates did not grow even at 1ppm. However, conidia, formed in vitro, germinated in suspensions of these fungicides, irrespective of tolerant or sensitive isolate. Tolerant isolates exhibited vigorous germ tube elongation, but sensitive isolates produced only short germ tubes in these suspensions. In a protection test on Japanese pear treated with 100ppm of each fungicide, tolerant isolates developed sporulating lesions. Tolerance of V. nashicola to thiophanate-methyl and benomyl in the field was therefore demonstrated.
    Download PDF (874K)
  • Hiroshi OTANI, Michiaki MORIKAWA, Syoyo NISHIMURA, Keisuke KOHMOTO
    1977 Volume 43 Issue 5 Pages 562-568
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The host-specific toxin (AK-toxin) of Alternaria kikuchiana caused rapid increases in efflux of K+ from susceptible leaves of Japanese pear (Pyrus serotina). On the contrary, toxin caused a decrease in effluxes of Na+, Mg2+ and Ca2+ from susceptible tissues, as compared to efflux from control tissue. Toxin-induced loss of K+ was much greater in the presence of Na+, Mg2+ or Ca2+ in the ambient solution. Stimulation of toxin-induced leakage was evident immediately after adding these cations to toxin-treated tissues; when these cations were removed, loss of K+ reverted to the lower level. The stimulative effect of Na+ and Mg2+ increased as the concentrations were increased from 0.01 to 10mM; the effects of Ca2+ reached a plateau at 0.1 to 1.0mM and then rapidly decreased. Susceptible tissues, in the presence of Mg2+ at 10mM, lost most of their K+ by 3hr after exposure to toxin. When toxin-induced K+ efflux was stimulated by other cations, the tissues took up such cations. Na+ and Mg2+ uptakes by toxin-treated tissues continued to increase at a constant rate, but Ca2+ uptake leveled off gradually with time. These data show that AK-toxin affects permeability of susceptible plasma membrane to K+; the loss of K+ may be associated with the presence of certain other inorganic cations.
    Download PDF (738K)
  • Tokito TOMINAGA, Koushi NISHIYAMA, Tsutomu YAMAMOTO
    1977 Volume 43 Issue 5 Pages 569-574
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A new bacterial disease was found on leaves of egg plant grown under vinyl-house condition in winter of 1969 in Tokushima prefecture, Japan. The disease usually occurred on leaves, peduncles, and buds, and rarely occurred on stems, petioles, and fruit. The small necrotic spots appeared at first and they fused into large lesions with irregular margin. From this symptom, “necrotic leaf spot of egg plant” was proposed as the disease name.
    The pathogen attacked egg plant, pot marigold, lettuce, and tomato by artificial spraying inoculation. The bacteriological and serological characteristics of the pathogen were determined. The bacterium was aerobic, Gram negative, and motile by 1 to 7 polar flagella. It produced acid on Hugh-Leifson medium only under aerobic condition. It grew Uschinsky's and Cohn's solution, and did not change Litmus milk. It showed positive reaction in the test of production of green fluorescent pigment, Kovacs' oxidase, and β-glucosidase, while negative in arginine dihydrolase, hydrolysis of margarine, and potato rot. It did not produce hydrogen sulfide, levan, and 2-keto gluconate. It produced acid from glucose, fructose, galactose, glycerol, and mannitol, but no acid from sucrose, maltose, lactose, and salicin. It produced alkali from tartrate, malonate, and citrate. It could not grow at 35C. Optimum temperature for growth was 25C and thermal death point was 48C. Antiserum made from living whole cells of the isolate Ep-1, reacted to all of the 5 isolates of the pathogen tested in agar gel diffusion method, but did not react to other pseudomo-nads. On the basis of bacteriological and serological characteristics and pathogenicity, the present bacterium was identified as Pseudomonas cichorii (Swingle) Stapp 1928. This is the first report of this bacterium to occur on egg plant in the field. Pseudomonas calendulae (Takimoto) Dowson 1943 is thought to be synonym of P. cichorii.
    Download PDF (1240K)
  • Kensuke NABETA, Genichi KADOTA, Toshikazu TANI, Hiroshi SHIGA
    1977 Volume 43 Issue 5 Pages 575-582
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Two antifungal steroids were isolated from the water homogenate of oat primary leaves and were identified as 26-desglucoavenacosides (26-DGA) A and B, respectively. O"-Rhamnosylisoswertisin (RIS) and unidentified flavonoid (UF) were also isolated as inhibitors. Inhibition tests to germ tube growth of Puccinia coronata avenae showed that 26-DGA A and B were potent inhibitors (ED80=14μg/ml), compared with RIS and UF (ED50=1, 500 and 500μg/ml, respectively). The contents of 26-DGA A and B in the water homogenate from 1g fresh leaves were 280 and 930μg, respectively, while only trace amounts of 26-DGAs were detected in the hot methanol extract of intact leaves. In contrast, the contents of RIS and UF were 750 and 300μg/ml, respectively, in both the water homogenate and hot methanol extract. No inhibitor other these four substances could be obtained. It was indicated that antifungal activity of the water homogenate is mainly attributable to 26-DGAs, whereas that in intact leaves is due to RIS and UF. No participation of these four inhitors as preformed substances was suggested in the species-species specificity in oat-rust combinations.
    Download PDF (803K)
  • Ichiro FUJISAWA, Toshiya SUGIMOTO
    1977 Volume 43 Issue 5 Pages 583-586
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (825K)
  • Sakari KATO
    1977 Volume 43 Issue 5 Pages 587-589
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (344K)
  • Toshihiro KATSUBE, C.R. de VAZ
    1977 Volume 43 Issue 5 Pages 590-592
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (238K)
  • Kokichi TAKAHASHI, Mamoru SATO
    1977 Volume 43 Issue 5 Pages 593-597
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    A new type of disease of mulberry, necrotic spot with halo on leaves and generalchlorosis of young shoots, was found in Shimane Prefecture in 1971. The bacteriumisolated from infected leaves was similar to Pseudomonas mori in its bacteriologicaland serological properties and in its host range, hence was identified as a new strainof Ps. mori causing halo blight by means of its halo-inducing toxin.
    Download PDF (936K)
  • Norio SATO, Kohei TOMIYAMA
    1977 Volume 43 Issue 5 Pages 598-600
    Published: December 28, 1977
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (278K)
feedback
Top