• Title/Summary/Keyword: leaf inoculation

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Hydrogen Peroxide- and Nitric Oxide-mediated Disease Control of Bacterial Wilt in Tomato Plants

  • Hong, Jeum Kyu;Kang, Su Ran;Kim, Yeon Hwa;Yoon, Dong June;Kim, Do Hoon;Kim, Hyeon Ji;Sung, Chang Hyun;Kang, Han Sol;Choi, Chang Won;Kim, Seong Hwan;Kim, Young Shik
    • The Plant Pathology Journal
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    • v.29 no.4
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    • pp.386-396
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    • 2013
  • Reactive oxygen species (ROS) generation in tomato plants by Ralstonia solanacearum infection and the role of hydrogen peroxide ($H_2O_2$) and nitric oxide in tomato bacterial wilt control were demonstrated. During disease development of tomato bacterial wilt, accumulation of superoxide anion ($O_2{^-}$) and $H_2O_2$ was observed and lipid peroxidation also occurred in the tomato leaf tissues. High doses of $H_2O_2$ and sodium nitroprusside (SNP) nitric oxide donor showed phytotoxicity to detached tomato leaves 1 day after petiole feeding showing reduced fresh weight. Both $H_2O_2$ and SNP have in vitro antibacterial activities against R. solanacearum in a dose-dependent manner, as well as plant protection in detached tomato leaves against bacterial wilt by $10^6$ and $10^7$ cfu/ml of R. solanacearum. $H_2O_2$- and SNP-mediated protection was also evaluated in pots using soil-drench treatment with the bacterial inoculation, and relative 'area under the disease progressive curve (AUDPC)' was calculated to compare disease protection by $H_2O_2$ and/or SNP with untreated control. Neither $H_2O_2$ nor SNP protect the tomato seedlings from the bacterial wilt, but $H_2O_2$ + SNP mixture significantly decreased disease severity with reduced relative AUDPC. These results suggest that $H_2O_2$ and SNP could be used together to control bacterial wilt in tomato plants as bactericidal agents.

Effect of the Infection Times by Zucchini yellow mosaic virus on the Yield and Growth in Cucumber (ZYMV 감염시기가 오이 생육 및 수량에 미치는 영향)

  • Ko, Sug-Ju;Kim, Do-Ik;Kang, Beom-Ryong;Kim, Seon-Gon;Lee, Yong-Hwan;Choi, Hong-Soo
    • Research in Plant Disease
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    • v.15 no.3
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    • pp.175-182
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    • 2009
  • We investigated the effect of the infection times and infection degrees at transplanting time of Zucchini yellow mosaic virus (ZYMV) on the growth and yield of cucumber plants at the semi-forcing and the retarding culture in 2007. When cucumber was inoculated with ZYMV at transplanting time, 15, 30, 45, 60, and 75 days after transplanting, vine length, internode length, number of leaf of the plants and marketable yield largely decreased as the cucumber infected earlier. The regression models were obtained between the disease incidence levels at 20 days after transplanting as the inoculation degrees and the marketable yield of cucumber: y = $9333.1e^{-0.0317x}$ ($R^2$ = 0.8946) at the semi-forcing culture and y = $14695e^{-0.0303x}$ ($R^2$ = 0.8735) at the retarding culture. And the cucumber yield loss regression models between the symptoms incidence days from the final harvesting time and the rates of yield decrease were expressed as y=1.0851x - 6.7067 ($R^2$ = 0.9567) at the semi-forcing culture andy=1.0439x + 2.1321 ($R^2$ = 0.9674) at the retarding culture.

Ultra-structural Observations of Colletotrichum orbiculare on Cucumber Leaves Pre-treated with Chlorella fusca (Chlorella fusca를 전처리한 오이 잎에서 오이탄저병균의 초미세 감염구조 관찰)

  • Lee, Yun Ju;Kim, Su Jeong;Jeun, Yong Chull
    • Research in Plant Disease
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    • v.23 no.1
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    • pp.42-48
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    • 2017
  • Chlorella is one of the microorganisms which can live autotrophically by their own photosynthesis. It was previously revealed that pre-treatment of Chlorella fusca caused a suppression of appressorium formation on the cucumber leaves after inoculation with Colletothrichum orbiculare. In this study, the ultrastructures of C. orbiculare on the cucumber leaves pretreated with C. fusca were observed using both scanning electron microscope (SEM) and transmission electron microscope (TEM). The SEM images revealed that most fungal conidia and hyphae were attached with lots of C. fusca cells. Also, the conidia could germinate but not form appressorium, which is necessary to penetrate into host tissue. These observations suggested that C. fusca adjoined to the fungus may play a role in suppression of the appressorium formation. On the other hand, the observations of TEM showed no remarkable cytological differences on the ultrastructures of the intracellular hyphae between in the pre-treated and untreated leaves. It seemed that the fungus could grow in the pre-treated plant tissues as in the untreated one. Based on these observations, it is suggested that the suppression of appressorium on the leaf surfaces by the C. fusca cells may be a main cause of the reduction of the anthracnose disease.

Races and Dominant Population of Chinese Cabbage Clubroot Pathogen, Plasmodiophora brassicae in Korea (국내 배추 뿌리혹병균, Plasmodiophora brassicae의 race와 그 우점 양상)

  • Jang, Se-Jeong;Heo, Seung-Hwan;Jang, Chang-Soon;Kang, Sung-Woo;Lim, Yong-Pyo;Kim, Hong-Gi
    • Research in Plant Disease
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    • v.13 no.1
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    • pp.45-49
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    • 2007
  • Single spores were isolated from infected roots of Chinese cabbage with a typical clubroot symptom, collected from different Chinese cabbage cultivation areas in Korea. When the single spore isolates were inoculated on Chinese cabbage, radish, turnip, kale, leaf mustard and Williams' differential varieties, among 321 roots harvested two weeks after inoculation, a visual symptom was observed on only one root and light/uncommon symptoms were done on 70 roots. These 71 individuals were homogenized and used as inocula. These inocula caused generally higher pathogenicity than that of single spore. Finally 15 isolates, with enough growth for conducting further experiment, were selected. These 15 individuals were grouped four, seven, two and two into race 1, race 4, race 9 and race 11, respectively, using Williams' differential set. It was confirmed that race 4 were dominantly present in Korea. These 15 had been obtained from roots of Chinese cabbages, radishes and turnips inoculated with single resting spores and had shown pathogenicity to Laurentian and Wilhelmsburger belong to Rutabaga in Williams' differential variety set. Therefore, we assume that such characteristic pathotypes including race 4, especially, of P. brassicae showing strong pathogenicity to Chinese cabbage, radish and turnip may be dominant in Korea.

Root and Basal Stem Rot of Moth Orchid (Phalaenopsis spp.), Pung-nan (Neofinetia falcata) and Nadopung-nan (Aerides japonicum) Caused by Fusarium spp. (Fusarium spp.에 의한 호접란과 풍란류에 발생하는 뿌리 및 줄기기부썩음병)

  • Kim, Jin-Won;Chun, Se-Chul
    • Research in Plant Disease
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    • v.13 no.1
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    • pp.6-14
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    • 2007
  • Root and basal stem rot disease occurred on moth orchid (Phalaenopsis spp.), Pung-nan (Neofinetia falcata) and Nadopung-nan (Aerides japonicum) grown in the farmers' greenhouses located in Namyangju Kyonggi province, Korea during 2005 to 2006. Wilting symptoms occurred on these orchard plants at initial stage and the infected plant leaves turned yellow to red. The discolored leaves were fallen down to lead to eventual death of the entire plant. A total of 59 isolates of Fusarium spp. was obtained from roots and leaf bases of the diseased plants. The cultural and morphological characteristics of isolated Fusairum spp. were identified as Fusarium oxysporum, F. proliferatum and F. solani. F. oxysporum and F. proliferatum were isolated from all these orchard plants but F. solani was isolated only from Phalaenopsis spp. Pathogenicity of the three Fusarium spp. was confirmed by artificial inoculation. Although F. oxysporum, F. proliferatum and F. solani cusing root rot disease in Phalaenopsis spp. have been reported in Korea, the pathogens in N. falcata and A. japonicum were not reported yet. Therefore, this is the first report on the root and stem rot of N. falcata and A. japonicum caused by F. oxysporum and F. proliferatum in Korea.

Anthracnose of Pepper seedling caused by Colletotrichum coccodes (Wallr.) Hughes (Colletotrichum coccodes(Wallr.) Hughes에 의(依)한 고추 유묘탄저병(幼苗炭疽病))

  • Oh, In-Seok;In, Moo-Seong;Woo, In-Shik;Lee, Sung-Koo;Yu, Seung-Hun
    • The Korean Journal of Mycology
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    • v.16 no.3
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    • pp.151-156
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    • 1988
  • A leaf anthracnose disease of pepper(Capsicum annuum L.) seedling caused by Colletotrichum coccodes was found in fields of Chungnam District for the first time in 1988. Initial symptom of the disease was spotting on leaves and stems of the seedlings. The spots became sunken and gradually increased in size and coalesced to form bigger irregular spots and blights on the leaves. In severely affected fields, many pepper seedlings were defoliated and lodged. Field survey revealed that the infection rate of anthracnose ranged form 15.3% to 92.3%. Conidia from lesions on seedlings were hyaline, aseptate, straight, cylindrical with obtuse ends, $115-25(av.\;19.\;5){\times}2.5-4.8{\mu}m(av.\;3.3{\mu}m)$ and setaes were straightly extended above the acervuli, $41.3-136.3\;{\um}m(av.\;85.0{\mu}m)$ long. The fungus produced abundant sclerotia on PDA when it was cultured under darkness. In the inoculation experiments, the fungus was found to infect pepper seedlings and fruits, and fruits of tomato and egg plant.

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STUDIES ON THE TISSUE CULTURE OF PANAX GINSENG

  • Harn C
    • Proceedings of the Ginseng society Conference
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    • 1974.09a
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    • pp.9-22
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    • 1974
  • Unlike the tissue culture in animals and human being, in higher plants various parts of the plant are cultured for varied purposes, and they are named variously depending on which parts are used as explants or what purposes they are cultured for. Followings are some of the names of culture used frequently: organ culture, tissue culture, callus culture, single cell culture, meristem culture, mericlone culture, ovary culture, ovule culture, embryo culture, endosperm culture, anther culture, pollen culture, protoplast culture, etc.. As the names of the culture indicate, in some kinds of culture the explants used for culture are actually not tissues, but organs, single cells, or protoplasts. It seems, however, convenient to call all of the above-mentioned cultures grossly as tissue culture. Several kinds of tissue culture were attempted using Panax ginseng as material and some of the results were summarized below. 1. Callus culture After dormancy of the sed was broken, whole embryo or parts (hypocotyl, cotyledon and epicotyl) of partly grown embryo were cultured in the media supplemented with growth regulators. Rapid swelling occurred in a few weeks, but most of the swelling was observed only in the basal part of epicotyl, changes in the other parts of embryo appearing in much later stages. The swelling or increase in size, however, was resulted not from the divisions of cells, but from the mere expansion of cell. Real calli were formed about two months after inoculation of explants. Callus tissues developed from cortex, pith, and vascular bundle in the cases of hypo- and epicotyl, from mesophyl tissue in the case of cotyledon. Shoots developed more easily from cotyledons regardless of whether they are detached from or attached to the embryo proper. 2. Culture in the Knudson C medium When cotyledons, detached from or attached to the embryo proper, were cultured in the growth regulator-free Knudson C medium comprision only several kinds of mineral compounds and sucrose, shoot primordium or callus developed profusely and finally plantlets were produced directly from shoot primordium or indirectly through callus. In this medium epidermal cells as well as mesophyl cells of the cotyledon became meristematic and divided, changing into multinucleate cells or multicellular bodies, developing eventually into either shoot primordia or calli. 3. Anther culture Anthers were cultured in the media supplemented with various growth regulators applied singly or in combinations. Callus was formed mostly in the connective tissue of anther. Cells of anther wall layers changed in appearance, but no division occurred. Microspores of all stages in development were not changed, ruling out the possibility that microspore-originated callus might be formed. 4. Isolation of protoplast Protoplasts were isolated from young root, leaf, and epicotyl, using 0.7M D-mannitols as osmoticum and using macerozyme and cellulase respectively for maceration and digestion of the cell wall. Production in large number of naked intact protoplast was rather difficult as compared with other plant species. Fusion of protoplasts occurred infrequently mainly due to the fewer number of naked protoplasts in the solution.

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First Report of Summer Patch Caused by Magnaporthiopsis poae on Cool Season Grass (Magnaporthiopsis poae에 의한 한지형 잔디의 여름잎마름병 보고)

  • Han, Ju Ho;Ahn, Chang Hyun;Lee, Seung-Yeol;Back, Chang-Gi;Kang, In-Kyu;Jung, Hee-Young
    • The Korean Journal of Mycology
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    • v.44 no.3
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    • pp.196-200
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    • 2016
  • Symptoms of summer patch were observed on Kentucky bluegrass (Poa pratensis L.) cv. "Midnight II" from mid-June in 2015 in Seoul, Korea. The symptoms appeared as leaf blight, root rot, and frog-eye patch, which are typical of summer patch. To identify the causal agent of these symptoms, a pathogen was isolated from diseased leaves and roots, and the cultural, morphological, and phylogenetic characteristics were analyzed. The isolate reached 50-60 mm on potato dextrose agar (PDA) after 10 days as a white-grey mycelium with septa, and became olive-green or brown from the center. Phialide-like structures were observed at the ends of hyphae, and conidia were rarely observed. A phylogenetic analysis was conducted based on large subunit (LSU) and RNA polymerase II large subunit (RPB1) sequences. According to this analysis, the isolated pathogen was confirmed to be Magnaporthiopsis poae. In a pathogenicity test, summer patch symptoms were observed at 20 days after inoculation using the same grass cultivar. This is the first report of summer patch disease caused by M. poae on cool season grass in Korea.

Gall formation on different age, habitat, and parasite position in Rhus javanica L. (붉나무의 수령, 서식지 및 기생위치에 따른 오배자 형성)

  • Jo, Hyeong-Chan;Han, Kwang-Soo;An, Eun-Yong
    • Korean Journal of Medicinal Crop Science
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    • v.8 no.4
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    • pp.304-311
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    • 2000
  • This study was conducted to investigate the ratio and number of the Rhus javanica gall formed by chinese sumac aphid, Scheleechtendalia chinensis, in several different conditions in which R. javanica lives. The density of 11 to 15-year-old R. javanica was more higher and the number of galls was also higher than 1 to 5- or over 16-year-old one at these sites. The formed gall according to four directions such as the East, West, South and North was founded the highest at the East and followed South, North, and West order. The formative rate of R. javanica gall did not differ in the mixture forest, and in the habitat having a heap of a little stone and mosses near a valley was better than in the site of road perimeter. Through an index of the gall diameter and the number of chinese sumac aphid, we evaluated the gall processing and development formed by the aphid. As the density of aphids increase, the size of the gall was also more plumped. The part of phyllotaxy of R. javanica gall in leaf and pinnate of was increased in the middle and upper part of terminal leaflet and leaflet was more occupied than wing. R. javanica which did not form a gall in natural environmental, formed gall by a artificial inoculation of S. chinensis. Some gall disappeared during a gall development from various environmental conditions.

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Brown Ring Spot on Leaves of Kiwifruit Caused by Alternaria alternata (Alternaria alternata에 의한 참다래 갈색둥근무늬병)

  • Jeong, In-Ho;Kim, Gyung-Hee;Lim, Myoung-Taek;Hur, Jae-Seoun;Shin, Jong-Sup;Koh, Young-Jin
    • Research in Plant Disease
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    • v.14 no.1
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    • pp.68-70
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    • 2008
  • Brown leaf spots on leaves of kiwifruit(Actinidia deliciosa) were observed at farmers' orchards in Suncheon and Goheung, Jeonnam Province, Korea in June, 2006. They developed to form dark brown ring spots and severely infected leaves resulted in defoliation during the growing season of kiwifruit. Alternaria sp. was isolated from the diseased leaves repeatedly and was identified as Alternaria alternata on the basis of its mycological characteristics on potato dextrose agar and its pathogenicity was confirmed by wound inoculation on healthy leaves of kiwifruit. A. alternata formed gray to dark sooty gray colony and produced numerous conidia on potato dextrose agar. The conidia, commonly in long chains of 5 or more produced on conidiophores, have $3{\sim}5$ transverse and $1{\sim}2$ longitudinal septa and mostly ovoid or obclavate in shape and were pale brown golden brown in color. The condia were $16.5{\sim}42.1{\times}6.7{\sim}19.5\;{\mu}m$ in size and conidiophores were $8.6{\sim}112.7\;{\mu}m$ in length. This is the first report on the brown ring spot on leaves of kiwifruit caused by A. alternata in Korea.