• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1026-1035
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• 2011

Vibrio parahaemolyticus, which owes its origin to the marine environment, is considered as one of the most common causes of infectious diarrhea worldwide. The present study investigated the pathogenicity of V. parahaemolyticus against the model organism, Caenorhabditis elegans. Infection in the host was localized with GFP-tagged V. parahaemolyticus using confocal laser scanning microscopy. The times required for causing infection, bacterial load in intestine, chemotactic response, and alteration in pharyngeal pumping were analyzed in the host system. In addition, the regulation of innate immune-related genes, lys-7, clec- 60, and clec-87, was analyzed using real-time PCR. The role of immune-responsible pmk-1 was studied using mutant strains. The pathogenicity of environmental strain CM2 isolated from the Gulf of Mannar, India was compared with that of a reference strain obtained from ATCC. The pathogen infected animals appeared to ward off infection by up-regulating candidate antimicrobial genes for a few hours after the exposure, before succumbing to the pathogen. For the first time, the pathogenicity of V. parahaemolyticus at both the physiological and molecular levels has been studied in detail using the model organism C. elegans.

• Asian-Australasian Journal of Animal Sciences
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• 제16권9호
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• pp.1247-1253
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• 2003

Selection for increased milk production in dairy cows has often resulted in a higher incidence of disease and thus incurred a greater health costs. Considerable interests have been shown in breeding dairy cattle for disease resistance in recent years. This paper discusses the limitations of breeding dairy cattle for genetic resistance in six parts: 1) complexity of disease resistance, 2) difficulty in estimating genetic parameters for planning breeding programs against disease, 3) undesirable relationship between production traits and disease, 4) disease as affected by recessive genes, 5) new mutation of the pathogens, and 6) variable environmental factors. The hidden problems of estimating genetic and phenotypic parameters involving disease incidence were examined in terms of categorical nature, non-independence, heterogeneity of error variance, non-randomness, and automatic relationship between disease and production traits. In light of these limitations, the prospect for increasing genetic resistance by conventional breeding methods would not be so bright as we like. Since the phenomenon of disease is the result of a joint interaction among host genotype, pathogen genotype and environment, it becomes essential to adopt an integrated approach of increasing genetic resistance of the host animals, manipulating the pathogen genotypes, developing effective vaccines and drugs, and improving the environmental conditions. The advances in DNA-based technology show considerable promise in directly manipulating host and pathogen genomes for genetic resistance and producing vaccines and drugs for prevention and medication to promote the wellbeing of the animals.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.70.1-70
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• 2003

It was investigated whether culture filtrates produced by X. fastiduosa could be used to determine varietal susceptibility in grape cultivars to anthracnose as a substitute for pathogen inoculation or field screening. Bioassay of grape leaves with culture filtrates showed that their phytotoxicities were active and host-selective. Ethyl acetate extracts from those also showed the toxicities and host selectivity among grape cultivars. The sensitive range of plants to culture filtrates and their ethyl acetate extracts was consistent with the host range to the pathogen. Susceptible cultivars were sensitive to even highly diluted culture filtrates but resistant cultivars were not affected even at original culture filtrates. Susceptible cultivars were sensitive to the undiluted culture filtrates than highly diluted culture filtrates and the younger leaves were the more sensitive to the culture filtrates and their ethyl acetate extracts in grapes.

• The Plant Pathology Journal
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• 제36권1호
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• pp.98-105
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• 2020

Venturia nashicola is a fungal pathogen causing scab disease in Asian pears. It is particularly important in the Northeast Asia region where Asian pears are intensively grown. Venturia nashicola causes disease in Asian pear but not in European pear. Due to the highly restricted host range of Venturia nashicola, it is hypothesized that the small secreted proteins deployed by the pathogen are responsible for the host determination. Here we report the whole genome based phylogenetic analysis and predicted secretomes for V. nashicola isolates. We believe that our data will provide a valuable information for further validation and functional characterization of host determinants in V. nashicola.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2004년도 The 2004 KSPP Annual Meeting & International Symposium
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• pp.65-67
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• 2004

During initial interactions of bacteria with their host plants, most plants recognize the bacterial infections and repel the pathogen by plant defense mechanism. The most active plant defense mechanism is the hypersensitive response (HR) which is the localized induced cell death in the plant at the site of infection by a pathogen. A primary locus induced in gram-negative phytopathogenic bacteria during this initial interaction is the Hrp locus. The Hrp locus is composed of a cluster of genes that encodes the bacteral Type 111 machinery that is involved in the secretion and translocation of effector proteins to the plant cell. DNA sequence analysis of hrp gene in phytopathogenic bacteria has revealed a Hrp pathogenicity is]and (PAI) with a tripartite mosaic structure. For many gram-negative pathogenic bacteria, colonization of the host's tissue depends on the type III protein secretion system (TTSS) which secrets and translocates effector proteins into the host cell. Effectors can be divided into several groups including broad host range effectors, host specific effectors, disease specific effectors, and effectors inhibit host defenses. The role of effectors carrying LRR domain in plant resistance is very elusive since most known plant resistance gene carry LRR domain. Host specific effectors such as several avr gene products are involved in the determination of the host specificity. Almost all the phytopathogenic Xanthomonas spp. carry avrBs1, avrBs2, and avrBs3 homologs. Some strains of X. oryzae pv. oryzae carry more than 10 copies of avrBs3 homologs. However, the functions of all those avr genes in host specificity are not characterized well.;

• Journal of Plant Biotechnology
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• 제36권3호
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• pp.244-254
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• 2009

The hypersensitive reaction (HR) is the most common plant defense reaction against pathogens. HR is produced during both host- and nonhost-incompatible interactions. Several reports suggest that similarities exist between host and nonhost resistances. We assayed the pattern of generation of reactive oxygen species (ROS) and scavenging enzyme activities during nonhost pathogen-plant interactions (Xanthomonas campestris pv. campestris/Capsicum annuum L.) and incompatible host pathogen-plant interactions (Xanthomonas campestris pv. vesicatoria race1/Capsicum annuum L.). Both ${O_2}^-\;and\;H_2O_2 $ accumulated much faster during nonhost resistance when compared to the host resistance. The scavenging enzyme activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were also different during the host- and nonhost-incompatible interactions. CAT activity was much higher during nonhost resistance, and several new isozymes of SOD and POX were detected during nonhost resistance when compared to the host resistance. Lipoxygenase (LOX) activity was higher in host resistance than nonhost resistance during the early stages of infection. Interestingly, the nitric oxide (NO) radical accumulated equal amounts during both host and nonhost resistance at early stages of infection. Further studies are needed to determine the specific pathways underlying these differences between host and nonhost resistance responses.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.151-152
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• 2002

Bacterial infection is a very complex process in which both pathogenic microorganisms and host cells play crucial roles, and it is the outcome of interactions between the two participants. To elucidate the bacterial pathogenesis mechanisms, therefore, it is essential to understand the cellular and systemic responses of the host as well as the virulence factors of the pathogen. Infection of a host by pathogenic bacteria causes drastic changes in the physiology of host cells, leading to activation of a program of various gene expression. (omitted)

• 식물병과 농업
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• 제5권2호
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• pp.69-76
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• 1999

Acidovorax avenae subsp. avenae is the causal pathogen of several hosts including oats corn foxtail millet wheatgrass sugarcane and rice. The pathogen is a seedborne pathogen of rice and known to occur widely in rice growing countries. The pathogen cause inhibition of germination brown stripe on the leaf curling of the leaf sheath and abnormal elongation of the mesocotyl of irce. Bacterial colonies grow slowly and are convex circular and creamy with tan to brown center. The causal baterium is Gram-negative and rod shape with a single polar flagellum Nonfluorescence poly-$\beta$-hydroxybutyrate accumulation and precipitate formation around the colony on the medium are useful in the differentiation of this bacterium from other subspecies of A. avenae as well as nonfluorescent bacteria pathogenic to rice. This bacterium has belonged to the genus of Psdeudomonas but recently was transferred to the new genus Acidovorax on the basis of bacteriological and molecular biological data. However the difference of biochemical characteristics protein profile of the cell and host range among strains should be more clarified. To develop an effective control strategy for this disease understanding of detailed life cycle of the disease ritical environmental factors affecting disease development on each host and relationship to grain discoloration of rice are prerequisite. Although the affected area has been world-widely reported there is on recent progress on the understanding of the bacteriological and ecological characteristics of the causal bacterium and control means of the disease.

• ALGAE
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• 제32권1호
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• pp.29-39
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• 2017

Geographic distributions of pathogens are affected by dynamic processes involving host susceptibility, availability and abundance. An oomycete, Pythium porphyrae, is the causative agent of red rot disease, which plagues Pyropia farms in Korea and Japan almost every year and causes serious economic damage. We isolated an oomycete pathogen infecting Pyropia plicata from a natural population in Wellington, New Zealand. The pathogen was identified as Pythium porphyrae using cytochrome oxidase subunit 1 and internal transcribed spacer of the rDNA cistron molecular markers. Susceptibility test showed that this Pythium from New Zealand was able to infect several different species and genera of Bangiales including Pyropia but is not able to infect their sporophytic (conchocelis) phases. The sequences of the isolated New Zealand strain were also identical to Pythium chondricola from Korea and the type strain from the Netherlands. Genetic species delimitation analyses found no support for separating P. porphyrae from P. chondricola, nor do we find morphological characters to distinguish them. We propose that Pythium chondricola be placed in synonymy with P. porphyrae. It appears that the pathogen of Pyropia, both in aquaculture in the northern hemisphere and in natural populations in the southern hemisphere is one species.

• The Plant Pathology Journal
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• 제38권2호
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• pp.102-114
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• 2022

Pectobacterium carotovorum subsp. carotovorum (Pcc) is a gram-negative, broad host range bacterial pathogen which causes soft rot disease in potatoes as well as other vegetables worldwide. While Pectobacterium infection relies on the production of major cell wall degrading enzymes, other virulence factors and the mechanism of genetic adaptation of this pathogen is not yet clear. In the present study, we have performed an in-depth genome-wide characterization of Pcc strain ICMP5702 isolated from potato and compared it with other pathogenic bacteria from the Pectobacterium genus to identify key virulent determinants. The draft genome of Pcc ICMP5702 contains 4,774,457 bp with a G + C content of 51.90% and 4,520 open reading frames. Genome annotation revealed prominent genes encoding key virulence factors such as plant cell wall degrading enzymes, flagella-based motility, phage proteins, cell membrane structures, and secretion systems. Whereas, a majority of determinants were conserved among the Pectobacterium strains, few notable genes encoding AvrE-family type III secretion system effectors, pectate lyase and metalloprotease in addition to the CRISPR-Cas based adaptive immune system were uniquely represented. Overall, the information generated through this study will contribute to decipher the mechanism of infection and adaptive immunity in Pcc.