• Title, Summary, Keyword: 식물병원체

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Viroid-the Smallest Plant Pathogen (바이로이드-가장 작은 식물병원체)

  • Lee Jai Youl
    • Korean Journal Plant Pathology
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    • v.1 no.3
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    • pp.199-206
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    • 1985
  • Viroids are the smallest. well-characterized infectious agents presently known. and so far viroids have been found only in higher plants. The structures of viroid-molecules are single-stranded, covalently closed circular RNA molecules with a range of 240 to 380 nucleotides according to the various viroids. Viroids are remarkable not only as a new category of pathogen, which cause economically important diseases, but also as an excellent model system for biochemical and biophysical investigations because of their small size, relative stability and their self-replication. Four different patato spindle tuber viroid isolates, which express the different symptoms on the same host plant exchange only 2 to 6 nucleotides in the total number of 359 nucleotides, but now the mechanism of viroid pathogenicity is not explained fully. Viroid-melecules are replicated without any special viroid-associated proteins, and during the process of viroid replication oligomeric viroid-associated RNAs are detected at nuclei of viroid infected leaf tissue. The mechanism of viroid replication can now be illustrated according to a possible explanation of rolling-circle system. Although the rapid progress have been made in elucidation of the biochemical and biophysical properties of PSTV and other viroids, the mechanism of viroid replication and pathogenicity is less known and is still a matter of speculation. When these problems can be sufficiently explained, the viroid molecule could play an important role as an available vector in plant genetic engineering.

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Characteristics of Antifungal Bacterium, Bacillus subtilis YS1 and It′s Mutant Induced by Gamma Radiation (온천수로부터 분리한 항진균세균의 특성 및 감마선$(Co^{60})$ 조사를 이용한 돌연변이체 유기)

  • 이영근;김재성;송인근;정혜영;장화형
    • Korean Journal of Microbiology
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    • v.37 no.4
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    • pp.305-311
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    • 2001
  • Antifungal bacterium, Bacillus subtilis YS1 was isolated from Yusong hot spring showed broad antifungal spectrum against 12 kinds of plant pathogenic fungi and Candida albicans, animal pathogen. From the gamma($Co^{60}$) radiation sensitivity test, $D_10$ value was 2.08 kGy and it survived above 20 kGy of radiation dose. Several mutants were induced by gamma radiation. Among them, YS1-1009 mutant showed resistance against tebuconazole of herbicide, increased activity against Botryoshaeria dothidea and ligninase activity. YS67 mutant was antifungal deficient auxotrophic mutants(trp-pro-or arg-ura-). From this results, it suggested that gamma irradiation could be useful method for mutant induction.

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Structure-activity Analysis of Benzylideneacetone for Effective Control of Plant Pests (벤질리덴아세톤 화학구조 변이에 따른 생리활성 변화 분석 및 식물 병해충 방제 효과)

  • Seo, Sam-Yeol;Jun, Mi-Hyun;Chun, Won-Su;Lee, Sung-Hong;Seo, Ji-Ae;Yi, Young-Keun;Hong, Yong-Pyo;Kim, Yong-Gyun
    • Korean journal of applied entomology
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    • v.50 no.2
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    • pp.107-113
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    • 2011
  • Benzylideneacetone (BZA) is a compound derived from culture broth of an entomopathogenic bacterium, Xenorhabdus nematophila (Xn). Its immunosuppressive activity is caused by its inhibitory activity against eicosanoid biosynthesis. This BZA is being developed as an additive to enhance control efficacy of other commercial microbial insecticides. This study was focused on the enhancement of the immunosuppressive activity of BZA by generating its chemical derivatives toward decrease of its hydrophobicity. Two hydroxylated BZA and one sugar-conjugated BZA were chemically synthesized. All derivatives had the inhibitory activities of BZA against phospholipase $A_2$ ($PLA_2$) and phenoloxidase (PO) of the diamondback moth, Plutella xylostella, but BZA was the most potent. Mixtures of any BZA derivative with Bacillus thuringiensis (Bt) significantly increased pathogenicity of Bt. BZA also inhibited colony growth of four plant pathogenic fungi. However, BZA derivatives (especially the sugar-conjugated BZA) lost the antifungal activity. These results indicated that BZA and its derivatives inhibited catalytic activities of two immune-associated enzymes ($PLA_2$ and PO) of P. xylostella and enhanced Bt pathogenicity. We suggest its use to control plant pathogenic fungi.

Plant Cell Wall as an Inducer of Pectate Lyase of Erwinia rhapontice (Erwinia rhapontici의 Pectate Lyase를 유도하는 식물 세포벽)

  • 최재을;한광섭
    • Korean Journal Plant Pathology
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    • v.12 no.1
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    • pp.129-131
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    • 1996
  • Pecatate lyase(Pel)는 펙틴과 펙틴산을 분해하며, 기주식물의 감염에 관여한다. Erwinia rhapontici에 있어서 기주와 병원균이 병원성과의 상호관계를 구명하기 위하여 pectate lyase(Pel) 활성에 미치는 식물체 추출물과 세포벽의 효과를 검토하였다. 본 균은 glycerol이 포함된 minimal salts(MSG) 배지와 식물체 추출물이 첨가된 MSP 배지에서는 Pel 활성이 검출되지 않았다. 그러나 배추, 상추 잎, 감자 괴경, 셀러리 잎자루, 양파 인경, 당근 뿌리의 세포벽이 첨가된 MSP 배지에서는 Pel의 활성이 검출되었다. Pel을 유도하는 식물 인자는 불용성이고, 열처리에 불안전하였다.

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Effects of Lichen Colonization of Dirinaria applanata on the Death of Rhododendron schlippenbachii (철쭉나무(Rhododendron schlippenbachii)에 대한 엽상 지의류 Dirinaria applanata의 병원성 조사)

  • Oh, Soon-Ok;Koh, Young-Jin;Hur, Jae-Seoun
    • Research in Plant Disease
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    • v.13 no.1
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    • pp.34-39
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    • 2007
  • Lichen thalli of Dirinaria applanata heavily colonized on the twigs of dead or dying Rhododendron trees in Solok island, Jeonnam province in Korea. Pathogenesis of the lichen on the trees was investigated to find out the possibility of lichen as a causal agent. Histological examination of the lichen colonized twigs was attempted with differential staining technique. Lichen-forming fungus colonized only on the surface of bark and there was no direct penetration of fungal hyphae into the plant tissues. Symbiotic algae of the lichen was also examined. The isolated algal cells were inoculated on artificially induced wounds of the healthy trees. Histological examination of the inoculated tissues showed that some algal cells were successfully colonized inside the tissues without any pathogenic symptoms, even 2 months later, The extract of the lichen thalli was also examined using 10% of DMSO solution. Treated tissues showed no pathogenic symptoms, even 4 weeks later. The results suggested that the lichen was not directly involved in the death of the trees.

Occurrence and Distribution of Crop Diseases Caused by Invasive Alien Pathogens in Korea (외래침입 병원체에 의한 작물 병 발생 및 분포)

  • Cho, Weon-Dae;Hong, Sung-Kee;Kim, Wan-Gyu;Jee, Hyeong-Jin;Lee, Young-Kee;Choi, Hong-Soo;Kim, Chung*Hoe
    • Research in Plant Disease
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    • v.11 no.1
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    • pp.1-9
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    • 2005
  • Occurrence and distribution of crop diseases caused by invasive alien pathogens were surveyed in Korea from 2001 to 2003. Of 22 species of invasive alien pathogens surveyed, 18 species were found on their host plants but 4 species were not. Scientific names of the alien plant pathogens introduced into Korea in the past were reviewed. Revised scientific names of 10 species including anthracnose pathogens were amended in the list. Host ranges of invasive alien pathogens were investigated. Eight species of the invasive alien pathogens were found on new host plants as well as their host plants recorded in the past.

Fungicidal Activity of Domestic Plant Extracts against Six Major Phytopathogenic Fungi (국내산 식물체 추출물의 여섯 가지 주요 식물병원권에 대한 살균활성)

  • Park, Il-Kwon;Lee, Sang-Gil;Park, Ji-Doo;Shin, Sang-Chul;Ahn, Young-Joon
    • The Korean Journal of Pesticide Science
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    • v.7 no.2
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    • pp.83-91
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    • 2003
  • Methanol extracts from 207 samples of 118 plant species in 44 families were tested for their fungicidal activities against six phytopathogenic fungi. Extracts of Thuja orientalis leaf, Cinnamomum loureirii leaf, Lindera erythrocarpa barks and leaf, Pinus koraiensis wood, Hovenia dulcis wood, Koelreuteria paniculata barks, Styrax japonica wood, Camelia japonica leaf and Cleyera japonica leaf showed very strong fungicidal activity against more than two phytopathogenic fungi at a concentration of 2000 ppm. As a naturally occurring fungicide, these plants could be useful as new fungicidal products against various plant diseases induced by plant pathogens.

Occurrence and Distribution of Monosporascus Root Rot and Pathogenicity of Monosporascus cannonballus on Cucurbitaceae Plants (박과류 검은점뿌리썩음병의 발생분포 및 분리병원균의 병원성)

  • 허노열;류경열;현익화;권진혁
    • Research in Plant Disease
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    • v.7 no.1
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    • pp.11-15
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    • 2001
  • Root rot of Cucurbitaceae plants, caused by Monosporascus cannonballus, is one of the recently described diseases in Korea. The distribution and pathogenicity of M. cannonballus were examined by field and in vitro experiments. Root rot caused by M. cannonballus occurred on melon, oriental melon, watermelon and cucumber plants. In two years of disease survey, the disease occurred at 10 and 32 fields in 1997 and 1998, respectively, which were located at Kimhae, Chinju, and Namhae in Kyeongnam province, at Kwangyang in Chonnam province, at Kwangju city, and at Yeoju and Inchon in Kyeonggi province. The disease progress in a melon field at Namhae was not observed until the middle stage of plant growth, but rapidly increased at the fruit maturing stage, resulting in more than 50% yield loss. Isolation rate of M. cannonballus was 36.7% from wilted hosts. Fusarium oxysporum and Rhizoctonia solani were also frequently isolated. In vitro test, seedlings wilted after 7∼14 days of inoculation, and perithecia were formed in infected roots 21 days later. Two cucumber cultivars, Baekbong and Eunhwa, were resistant to the disease.

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The Bacterial Gall of Wistaria floribunda Caused by Pantoea agglomerans pv, milletiae (Pantoea agglomerans pv. milletiae에 의한 등나무 혹병)

  • 김종완;임진우
    • Research in Plant Disease
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    • v.7 no.3
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    • pp.145-149
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    • 2001
  • A pathogenic bacterium was isolated from galls on Wistaria floibunda at Jinryang of Kyungsan, Kyungbuk, Korea in May, 2000. This bacterium was cultured and tested for pathogenicity on the host. Also its morphological and physiological characteristics were examined. Inoculation with the bacterium isolated from the gall caused the same symptoms as those under natural conditions. On the basis of bacteriological characteristics and pathogenecity on the host plant of the organism, the causal bacterium was identified as Pantoea agglomerans pv. milletiae. This is the first report of this bacterium to occur on W. floribunda plant in Korea. Therefore we proposed to name the disease as "bacterial gall of Wistaria floribunda" by P. agglomerans pv. milletiae.milletiae.

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