• The Plant Pathology Journal
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• 제31권3호
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• pp.245-251
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• 2015

Alternative hosts increase the difficulty of disease management in crops because these alternate hosts provide additional sources of primary inoculum or refuges for diversity in the pathogen gene pool. Agropyron cristatum (crested wheatgrass), Bromus inermis (smooth bromegrass), Pascopyrum smithii (western wheatgrass), Stipa viridula (green needlegrass), and Thinopyrum intermedium (intermediate wheatgrass), commonly identified in range, prairie, verge, and soil reclamation habitats, serve as additional hosts for Pyrenophora tritici-repentis, the cause of tan spot in wheat (Triticum aestivum L.). A. cristatum (five lines), B. inermis (seven lines), P. smithii (four lines), S. viridula (two lines), and T. intermedium (six lines) were tested for their reactions to 30 representative P. tritici-repentis isolates from races 1-5. Plants were grown until the two-three-leaf stage in a greenhouse, inoculated individually with the 30 isolates, held at high humidity for 24 h, and rated after 7 days. All lines developed lesion types 1-2 (resistant) based on a 1-5 rating scale. Also, leaves from an additional plant set were infiltrated with two host selective toxins, Ptr ToxA as a pure preparation and Ptr ToxB as a dilute crude culture filtrate. All lines were insensitive to the toxins. Results indicate that these grass hosts have a limited or nonsignificant role in tan spot epidemiology on wheat in the northern Great Plains. Additionally, the resistant reactions demonstrated by the grass species in this research indicate the presence of resistance genes that can be valuable to wheat breeding programs for improving wheat resistance to P. tritici-repentis.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 춘계학술대회 및 임시총회
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• pp.60-60
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• 2015

Hybrid histidine kinase is a part of two-component system that is required for various stress responses and pathogenesis of pathogenic fungi. In the present study, Tco1, a homologue of human pathogen Cryptococcus neoformans Tco1 encoding a hybrid histidine kinase, was identified in corn smut pathogen Ustilago maydis by bioinformatic analysis. To explore the role of Tco1 in the virulence of U. maydis, mutants in which the tco1 gene was partially deleted were constructed by allelic exchange. The U. maydis tco1 mutants did show unaltered growth rate on axenic medium but were unable to produce conjugation tubes and develop fuzzy filaments, resulting in impaired mating of compatible strains. The expression levels of prf1, pra1, and mfa1 which are involved in the pheromone pathway significantly decreased in the tco1 mutants. In inoculation tests to host, the tco1 mutants showed significantly reduced ability in the production of anthocyanin pigments and tumor development on maize leaves. Overall, the combined results indicated that Tco1 plays important roles in sexual development and virulence of U. maydis by regulating the expression of the genes involved in the pheromone pathway.

• Journal of Microbiology and Biotechnology
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• 제17권3호
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• pp.474-480
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• 2007

Fusarium wilt of cucumbers was effectively controlled by Escherichia coli expressing an endochitinase gene (chiA), and the rate was as effective (60.0%) as the wild-type strain S. proteamaculans 3095 (55.0%) where the gene was cloned. However, live cells of soil inoculated E. coli host harboring the chiA gene did not proliferate but declined 100-fold from $10^8$ CFU during the first week and showed less than 10 cells after day 14, suggesting that E. coli was able to express and produce the chitinase enzyme to the soil even as the population was gradually decreasing. Because the majority of the strains was alive for only a short period of time and the Fusarium-affected seedlings showed symptoms of wilting within 7-10 days, it seems that the pathogen control was decided early after the introduction of the biocontrol agent, eliminating the survival of the antagonist. These results indicated that soil inoculated E. coli could sufficiently express and produce the recombinant protein to control the pathogen, and root or soil colonization of the antagonist might not be a significant factor in determining the efficacy of biological control.

• The Plant Pathology Journal
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• 제34권5호
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• pp.367-380
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• 2018

Stems and pods of hyacinth bean cultivated in a farmer's field in Gazipur District, Bangladesh, were found rotted in nearly 5% hyacinth bean plants. A fungus having fluffy mycelium and large sclerotia was isolated from affected tissues. Combined results of morphological, molecular and pathological analyses identified the fungus as Sclerotinia sclerotiorum (Lib) de Bary. Inoculating the fungus on healthy hyacinth bean plants and pods reproduced the symptoms previously observed in the field. The three isolates obtained from naturally infected plants were cross inoculated in hyacinth bean, okra and African-American marigold and they were pathogenic to these hosts. The optimum temperature and pH for its growth were $20^{\circ}C$ and pH 5.0, respectively. Sclerotial development was favored at pH 5.0. Sucrose and mannitol were the best carbon sources to support hyphal growth, while glucose was the most favourable for sclerotial development. The hyacinth bean genotypes, HB-82 (Rupban Sheem) and HB-102 were found highly resistant, while HB-94 (Ashina) was moderate resistant to the fungus. Finally, S. sclerotiorum was sensitive to Bavistin, Dithane M-45 and Rovral fungicides and Ca in the form of $CaCl_2$. This observation could possibly aid in eliminating field loss in hyacinth bean caused by an emerging pathogenic fungus S. sclerotiorum.

• 한국응용곤충학회지
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• 제19권4호
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• pp.228-233
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• 1980

The infection rate of soybean black root rot disease caused by Calonectria crotalariae was about $14\%$. The isolated fungi from the infected soybean roots and stems were Calonectria crotalariae, Fusarium solani, F. roseum, Phomopsis sojae, Pythium aphanidermatum, Rhizoctonia solani and Macrophomina sp. Among them, C. crotalariae was the most virulent pathogen under the laboratory conditions. Mycelial growth and microsclerotial formation were good on PSA containing 1000cc of water, 100g of potato and 20g of sugar. Mycelial growth, sporulation and microsclerotial formation were good on sterilized root. Perithecial formation was better in the dark condition than in the light. Survival of macroconidia was not available between $0\~25\%$ soil water content. Microsclerotia and mycelium in infected plant debris were survived for 4 months at to $8\%\;50\%$ soil water content. The plant height, when inoculated with $1.2\%$ inoculum density, reached approximately half of uninoculated plants. Disease severity was much higher at nonsterilized soil than completely sterilized soil. It was determined that the host range of this pathogen includes soybean, peanut, green bean and red bean.

• 동의생리병리학회지
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• 제26권4호
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• pp.409-417
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• 2012

External pathogens such as wind, cold can easily invade the external parts of the body when host's external defense ability is not secure. Herein, we consider the underlying mechanisms against the external contraction at the body surface. During the early period after primary invasion, external defense mechanisms are gradually activated. The classic clinical manifestations are aversion to cold, fever, headache, generalized pain, and nasal congestion. This condition is called by invasion of external pathogen into the body surface. As the disease progress, lung qi is stagnated and thereby up-outward and downward movement action of lung become disturbed. Therefore, when doctor administrate formula to treat the exterior syndrome, doctor must keep in mind not only materia medica, but also underlying mechanisms through which many clinical symptoms appear.

• 식물병연구
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• 제24권2호
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• pp.87-98
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• 2018

곰팡이 종들은 유전체내에 대략 10% 정도의 다양한 전이인자와 함께 반복적인 염기서열을 갖는다. 이러한 전이인자들의 대부분은 유전체내에서 활발히 전이되며 곰팡이 병원균의 기주 범위와도 연관성을 갖으며 분포하는 것으로 알려져있다. 화본과 작물에 병을 일으키는 도열병에 분포하는 전이인자들은 활발히 전이하는 것으로 보이며, 특정 기주에 감염하는 개체군에 특이적으로 분포하는 경우가 많았다. 다수의 연구 보고에서도열병균의 전이인자가 비병원성 유전자의 기능을 상실하는데 작용하여, 이로인해 저항성 품종에 병을 일으켰다. 따라서, 도열병균의 전이인자들은 식물-곰팡이 사이의 상호 진화를 유도하는 원동력 중 하나일 수 있다. 본 총설에서는 도열병균에 존재하는 전이인자들의 종류와 생물학적인 기능에 관해 정리하였다.

• Journal of Applied Biological Chemistry
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• 제50권4호
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• pp.227-233
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• 2007

We characterized a full-length cDNA of CaCOP1 from pepper. Phylogenetic analysis based on the deduced amino acid sequence of CaCOP1 cDNA revealed high sequence similarity to the COP1 gene in Oryza sativa (84% identity). CaCOP1 shares high sequence identity with regulatory protein in Arabidopsis (84%), constitutively photomorphogenic 1 protein in Pisum sativum (81%) and COP1 homolog in Lycopersicon esculentum (79%). CaCOP1 gene exists single copy in the chili pepper genome. Expression of CaCOP1 was reduced in response to inoculation of non-host pathogens. The expression of this gene under abiotic and oxidative stresses was investigated, including 200 mM NaCl, 200 mM mannitol, cold ($4^{\circ}C$), 100 ${\mu}M$ abscisic acid (ABA), and 10 mM hydrogen peroxide ($H_2O_2$). CaCOP1 was induced significantly 3 h after low temperature treatment but not by dehydration or high salinity. Moreover, CaCOP1 was not induced by plant hormone ABA. These observations suggest that CaCOP1 gene plays a role in abiotic stress and may be belong to ABA-independent regulation system.

• 미생물학회지
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• 제38권1호
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• pp.19-25
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• 2002

Colletotrichum spp.는 광범위한 기주범위를 갖는 다범성균으로 각종작물에 피해를주는 중요한식물병원진균이다. 최근 국내에서 널리 재배되고 있는 단감, 사과, 복숭아, 포도 등에 탄저병 이 발생하여 많은 경제적 손실을 초래하고 있다. 탄저병원균의 경우 기존에는 주로 형태적 특징이나 배지 상에서의 특성, 기주에 대한 병원성의 차이에 의존하여 분류를 해 왔다. 그러나 최근에는 병원균의 분류에 있어 문제점을 해결하기 위하여 분자생물학적 방법을 이용하고 있다. 이에 본 실험에서는 Random Amplified Polymorphism DNAs (RAPD)와 Ploymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) 기법을 이용하여 단감나무에 탄저병을 일으키는 균들 간에 유연관계를 밝혔다. 유연관계 분석결과 크게는2개의 그룹으로 나뉘었고 작게는5개의 그룹으로 나뉘는 것을 알 수 있었다.

• The Plant Pathology Journal
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• 제17권1호
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• pp.45-51
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• 2001

A root rot/vine decline disease occurred naturally on bottle gourd-stocked watermelon, melon, oriental melon and squash grown in greenhouses, but not on these plants grown in fields. Self-rooted watermelon, cucumber, pumpkin and luffa were also proven to be hosts of the pathogen by artificial inoculation in this experiment. The pathogen was identified as Monosporascus cannonballus by comparing microscopic characteristics of fungal structures with those of previously identified fungal strains. Our field investigations showed that the temperature and electric conductivity of soil in infected greenhouses were higher and the soil moisture content was lower than in noninfected greenhouses. To investigate soil-environmental factors affecting disease development, greenhouse trials and inoculation experiments were conducted. The host plants inoculated and grown under conditions of high soil temperature and electrical conductivity ($35\pm2^{\circ}$, 3.2-3.5 mS) and with low soil moisture content (pF 3.0-4.5) were most severely damaged by the fungal disease. Since plants growing in greenhouses ae usually exposed to such environmental conditions, this may be the reason why the monosporascus root rot/vine decline disease has occurred only on cucurbits cultivated in greenhouses but not in field conditions.