• The Plant Pathology Journal
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• v.36 no.5
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• pp.418-427
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• 2020

Xanthomonas campestris pv. campestris (Xcc), the pathogen of black rot which is the most destructive disease of Brassica vegetables throughout the world. Here, we reported two novel sequence-characterized amplified region (SCAR) markers (i.e., XccR6-60 and XccR6-67) for the detection of Xcc race 6 via re-alignment of the complete genome sequences of Xcc races/strains/pathovars. The specificity of SCAR primer sets was verified by mean of PCR amplification using the genomic DNA template of Xcc races/strains/pathovars and two other plant infecting bacterial strains. The PCR result revealed that the XccR6-60 and XccR6-67 primer sets amplified 692-bp and 917-bp DNA fragments, respectively, specifically from race 6, while no visible amplification was detected in other samples. In addition, the SCAR primers were highly sensitive and can detect from a very low concentration of genomic DNA of Xcc race 6. However, the complete genome sequence of Xcc race 6 is not yet publicly available. Therefore, the cloning and sequencing of XccR6-60 and XccR6-67 fragments from race 6 provide more evidence of the specificity of these markers. These results indicated that the newly developed SCAR markers can successfully, effectively and rapidly detect Xcc race 6 from other Xcc races/strains/pathovars as well as other plant pathogenic bacteria. This is the first report for race-specific molecular markers for Xcc race 6.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1269-1279
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• 2014

Xanthomonas oryzae pv. oryzae (Xoo) strains are plant pathogenic bacteria that can cause serious blight of rice, and their virulence towards plant host is complex, making it difficult to be elucidated. Caenorhabditis elegans has been used as a powerful model organism to simplify the host and pathogen system. However, whether the C. elegans is feasible for studying plant pathogens such as Xoo has not been explored. In the present work, we report that Xoo strains PXO99 and JXOIII reduce the lifespan of worms not through acute toxicity, but in an infectious manner; pathogens proliferate and persist in the intestinal lumen to cause marked anterior intestine distension. In addition, Xoo triggers (i) the p38 MAPK signal pathway to upregulate its downstream C17H12.8 expression, and (ii) the DAF-2/DAF-16 pathway to upregulate its downstream gene expressions of mtl-1 and sod-3 under the condition of daf-2 mutation. Our findings suggest that C. elegans can be used as a model to evaluate the virulence of Xoo phytopathogens to host.

• The Plant Pathology Journal
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• v.28 no.1
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• pp.68-74
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• 2012

Biocontrol microbes have mainly been screened among large collections of microorganisms $via.$ nutrient-rich $in$ $vitro$ assays to identify novel and effective isolates. However, thus far, isolates from only a few genera, mainly spore-forming bacilli, have been commercially developed. In order to isolate field-effective biocontrol microbes, we screened for more than 200 oligotrophic bacterial strains, isolated from rhizospheres of various soil samples in Korea, which induced systemic resistance against the soft-rot disease caused by $Pectobacterium$ $carotovorum$ SCC1; we subsequently conducted in $planta$ bioassay screening. Two oligotrophic bacterial strains were selected for induced systemic disease resistance against the $Tobacco$ $Mosaic$ $Virus$ and the gray mold disease caused by $Botrytis$ $cinerea$. The oligotrophic bacterial strains were identified as $Pseudomonas$ $manteilii$ B001 and $Bacillus$ $cereus$ C003 by biochemical analysis and the phylogenetic analysis of the 16S rRNA sequence. These bacterial strains did not exhibit any antifungal activities against plant pathogenic fungi but evidenced several other beneficial biocontrol traits, including phosphate solubilization and gelatin utilization. Collectively, our results indicate that the isolated oligotrophic bacterial strains possessing induced systemic disease resistance could provide useful tools as effective biopesticides and might be successfully used as cost-effective and preventive biocontrol agents in the field.

• The Plant Pathology Journal
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• v.33 no.4
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• pp.370-381
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• 2017

Rathayibacter tritici, which is a Gram positive, plant pathogenic, non-motile, and rod-shaped bacterium, causes spike blight in wheat and barley. For successful pathogenesis, R. tritici is associated with Anguina tritici, a nematode, which produces seed galls (ear cockles) in certain plant varieties and facilitates spread of infection. Despite significant efforts, little research is available on the mechanism of disease or bacteria-nematode association of this bacterium due to lack of genomic information. Here, we report the first complete genome sequence of R. tritici NCPPB 1953 with diverse features of this strain. The whole genome consists of one circular chromosome of 3,354,681 bp with a GC content of 69.48%. A total of 2,979 genes were predicted, comprising 2,866 protein coding genes and 49 RNA genes. The comparative genomic analyses between R. tritici NCPPB 1953 and R. toxicus strains identified 1,052 specific genes in R. tritici NCPPB 1953. Using the BlastKOALA database, we revealed that the flexible genome of R. tritici NCPPB 1953 is highly enriched in 'Environmental Information Processing' system and metabolic processes for diverse substrates. Furthermore, many specific genes of R. tritici NCPPB 1953 are distributed in substrate-binding proteins for extracellular signals including saccharides, lipids, phosphates, amino acids and metallic cations. These data provides clues on rapid and stable colonization of R. tritici for disease mechanism and nematode association.

• Research in Plant Disease
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• v.17 no.1
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• pp.44-51
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• 2011

The aim of this study was to develop specific and sensitive PCR-based procedures for simultaneous detection of economically important plant seed infection pathogenic bacteria and virus, Xanthomonns campestris pv. vesicatoria (Xcv), Clavibacter michiganensis subsp. michiganensis (Cmm), Erwinia carotovora subsp. carotovora (Ecc), Pepper mild mottle virus (PMMoV) and Tobacco mild green mosaic virus (TMGMV) in pepper and tomato seeds. Most of pepper and tomato bacterial and virus diseases are responsible for germination and growth obstruction. PCR with arbitral primers: selection of specific primers, performance of PCR with specific primers and determination of the threshold level for pathogens detection. To detect simultaneously the Xcv, Cmm, Ecc, PMMoV and TMGMV in pepper and tomato seeds, five pairs (Cmm-F/R, Ecc-F/R, Xcv-F/R, PMMoV-F/R, TMGMV-F/R) of specific primer were synthesized by primer-blast program. The multiplex PCR for the five pathogens in pepper and tomato seeds could detect specially without interference among primers and/or cDNA of plant seeds and other plant pathogens. The PCR result for pathogen detection using 20 commercial pepper and 10 tomato seed samples, Ecc was detected from 4 pepper and 2 tomato seed samples, PMMoV was detected from 1 pepper seed sample, and PMMoV and TMGMV were simultaneously detected from 1 pepper seed sample.

• Food Science of Animal Resources
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• v.32 no.1
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• pp.103-111
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• 2012

This study was carried out to examine foodborne pathogenic contamination from 1,080 samples of cooked hams and sausages at 10 Korean processing facilities in 2010. The samples were collected from the six primary and additional sterilization products in same lot. To detect Salmonella spp., Staphylococcus aureus, Listeria monocytogenes and Clostridium perfringens in those products (n=1,080), the domestic standard method for Processing and Ingredients Specification of Livestock Products was used. As a result, Salmonella spp. was not detected in all 636 ham and 444 sausage samples. However, L. monocytogenes was detected in four (0.6%) ham and eight (1.8%) sausage samples from five manufactures. S. aureus was also only detected in 4 (0.6%) ham samples from two manufacturers, and C. perfringens was detected in 3 (0.5%) ham samples from three manufacturers, the contamination levels of these pathogens were less than 100 CFU/g. In conclusion, the results of this study indicate that the additional sterilization step of processing manufacturers could not assist to control the foodborne pathogenic bacteria.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.945-955
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• 2016

To date, chemical managements of plant bacterial diseases are complicated by limitations on use of antibiotics in agriculture, antibiotic resistance development, and limited efficacy of alternative control agents. In this study, thus, we performed screening of eco-friendly farming material (notice no. 2-4-064) containing tannic acid as new antibacterial-activity against 7 plant bacterial pathogens: Pectobacterium carotovorum subsp. carotovorum (Pcc), Ralstonia solanacearum (Rs), Acidovorax avenae subsp. citrulli (Aac), Xanthomonas cirti pv. citri (Xcc), Erwinia pyrifoliae (Ep), Clavibacter michiganensis subsp. michiganensis (Cmm), and Streptomyces scabies (Sc), Initial screening of antibacterial effects of eco-friendly farming material was performed using the paper disk diffusion method and co-cultivation in broth culture. Tannic acid based eco-friendly farming material showed inhibitory effect against Pcc, Rs, Aac, Xcc, Cmm, and Ss, whereas it did not show inhibition zone against Ep. However, when it tested by co-cultivation in broth culture, it showed strong inhibition effect against all pathogens that declined growth curve compared to bacterial pathogen only. Interestingly, when we observed morphological changes on those pathogens by SEM, cell morphologies of 7 pathogens were slightly changed that seem to be malfunction in their cell envelope.

• BMB Reports
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• v.41 no.3
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• pp.259-265
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• 2008

Three peroxidase (POD) cDNAs were isolated from dehydration-treated fibrous roots of sweetpotato (Ipomoea batatas) plant via the screening of a cDNA library, and their expressions were assessed to characterize functions of each POD in relation to environmental stress. Three PODs were divided into two groups, designated the basic PODs (swpb4, swpb5) and the anionic PODs (swpa7), on the basis of the pI values of mature proteins. Fluorescence microscope analysis indicated that three PODs are secreted into the extracellular space. RT-PCR analysis revealed that POD genes have diverse expression patterns in a variety of plant tissues. Swpb4 was abundantly expressed in stem tissues, whereas the expression levels of swpb5 and swpa7 transcripts were high in fibrous and thick pigmented roots. Swpb4 and swpa7 showed abundant expression levels in suspension cultured cells. Three POD genes responded differently in the leaf and fibrous roots in response to a variety of stresses including dehydration, temperature stress, stress-associated chemicals, and pathogenic bacteria.

• Journal of Life Science
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• v.23 no.12
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• pp.1415-1419
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• 2013

Electron beam (EB) irradiation was tested to determine the dose required to eradicate plant pathogens, such as Botrytis cinerea and Agrobacterium rhizogenes, from the infected seeds without affecting the germination rate of the irradiated vegetable seeds, including crown daisy, cucumber, hot pepper, green onion, leaf lettuce, and radish seeds. EB irradiation of 1.5 kGy and 2 kGy was sufficient to kill 100% of hairy root disease bacteria and gray mold conidia, respectively. EB irradiation showed no effect or minimal effect on the germination rate of the crown daisy, cucumber, green onion, and radish seeds. However, the germination rate of the hot pepper and leaf lettuce seeds was significantly reduced by using 2 kGy of EB irradiation. Difference in susceptibility to EB irradiation appears not to be related to the weight of each seed, but to the intrinsic characteristic of each plant. Conclusively, EB irradiation might be a useful way to decontaminate crown daisy, cucumber, green onion, and radish seeds.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.445-458
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• 2019

The lipopolysaccharide (LPS) composed of lipid A, core, and O-antigen is the fundamental constituent of the outer membrane in gram-negative bacteria. This study was conducted to investigate the roles of LPS in Burkholderia glumae, the phytopathogen causing bacterial panicle blight and seedling rot in rice. To study the roles of the core oligosaccharide (OS) and the O-antigen region, mutant strains targeting the waaC and the wbiFGHI genes were generated. The LPS profile was greatly affected by disruption of the waaC gene and slight reductions were observed in the O-antigen region following wbiFGHI deletions. The results indicated that disruption in the core OS biosynthesis-related gene, waaC, was associated with increased sensitivity to environmental stress conditions including acidic, osmotic, saline, and detergent stress, and to polymyxin B. Moreover, significant impairment in the swimming and swarming motility and attenuation of bacterial virulence to rice were also observed in the waaC-defective mutant. The motility and virulence of O-antigen mutants defective in any gene of the wbiFGHI operon, were not significantly different from the wild-type except in slight decrease in swimming and swarming motility with wbiH deletion. Altogether, the results of present study indicated that the LPS, particularly the core OS region, is required for tolerance to environmental stress and full virulence in B. glumae. To our knowledge, this is the first functional study of LPS in a plant pathogenic Burkholderia sp. and presents a step forward toward full understanding of B. glumae pathogenesis.