• Title, Summary, Keyword: Plant pathogen

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The Hypersensitive Response. A Cell Death during Disease Resistance

  • Park, Jeong-Mee
    • The Plant Pathology Journal
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    • v.21 no.2
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    • pp.99-101
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    • 2005
  • Host cell death occurs during many, but not all, interactions between plants and the pathogens that infect them. This cell death can be associated with disease resistance or susceptibility, depending on the nature of the pathogen. The most well-known cell death response in plants is the hypersensitive response (HR) associated with a resistance response. HR is commonly regulated by direct or indirect interactions between avirulence proteins from pathogen and resistance proteins from plant and it can be the result of multiple signaling pathways. Ion fluxes and the generation of reactive oxygen species commonly precede cell death, but a direct involvement of the latter seems to vary with the plant-pathogen combination. Exciting advances have been made in the identification of cellular protective components and cell death suppressors that might operate in HR. In this review, recent progress in the mechanisms by which plant programmed cell death (PCD) occurs during disease resistance will be discussed.

Platform of Hot Pepper Defense Genomics: Isolation of Pathogen Responsive Genes in Hot Pepper (Capsicum annuum L.) Non-Host Resistance Against Soybean Pustule Pathogen (Xanthomonas axonopodis pv. glycines)

  • Lee, Sang-Hyeob;Park, Do-Il
    • The Plant Pathology Journal
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    • v.20 no.1
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    • pp.46-51
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    • 2004
  • Host resistance is usually parasite-specific and is restricted to a particular pathogen races, and commonly is expressed against specific pathogen genotypes. In contrast, resistance shown by an entire plant species to a species of pathogen is known as non-host resistance. Therefore, non-host resistance is the more common and broad form of disease resistance exhibited by plants. As a first step to understand the mechanism of non-host plant defense, expressed sequence tags (EST) were generated from a hot pepper leaf cDNA library constructed from combined leaves collected at different time points after inoculation with non-host soybean pustule pathogen (Xanthomonas axonopodis pv. Glycines; Xag). To increase gene diversity, ESTs were also generated from cDNA libraries constructed from anthers and flower buds. Among a total of 10,061 ESTs, 8,525 were of sufficient quality to analyze further. Clustering analysis revealed that 55 % of all ESTs (4685) occurred only once. BLASTX analysis revealed that 74% of the ESTs had significant sequence similarity to known proteins present in the NCBI nr database. In addition, 1,265 ESTs were tentatively identified as being full-length cDNAs. Functional classification of the ESTs derived from pathogen-infected pepper leaves revealed that about 25% were disease- or defense-related genes. Furthermore, 323 (7%) ESTs were tentatively identified as being unique to hot pepper. This study represents the first analysis of sequence data from the hot pepper plant species. Although we focused on genes related to the plant defense response, our data will be useful for future comparative studies.

INDUCTION OF SYSTEMIC RESISTANCE IN CUCUMBER AGAINST ANTHRACNOSE BY PLANT GROWTH PROMOTING FUNGI

  • Hyakumachi, Mitsuro
    • Proceedings of the Korean Society of Plant Pathology Conference
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    • pp.47-55
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    • 1997
  • Plant growth promoting fungi(PGPF) obtained from zoysiagrass rhizosphere offer dual advantages - induse systemic disease resistance response in cucumber to C. orbiculare infection and cause enhancement of plant growth and increase yield. PGPF protected plants either by colonizing roots or by their metabolites. PGPF offer an advantage by protecting plants for more than 9 weeks and 6 week in the greenhouse and field. PGPF-induced plants limited pathogen spore germination and decreased the number of infection hyphae on the leaf, and increased lignification at places of attempted pathogen infection, thus reducing the pathogen spread. PGPF elicited increased activities of chitinascs, glucanases, peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase to C. orbiculare infection in cucumber plants. The role of PGPF in elevating cucumber defense response to pathogen infection suggests potential application of PGPF as biological control agents.

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Toward Functional Genomics of Plant-Pathogen Interactions: Isolation and Analysis of Defense-related Genes of Rot Pepper Expressed During Resistance Against Pathogen

  • Park, Do-Il;Lee, Sang-Hyeob
    • The Plant Pathology Journal
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    • v.18 no.2
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    • pp.63-67
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    • 2002
  • To understand plant-pathogen interactions, a complete set of hot pepper genes differentially expressed against pathogen attack was isolated. As an initial step, hundreds of differentially expressed cDNAS were isolated from hot pepper leaves showing non-host resistance against bacterial plant pathogens (Xanthomonas campestris pv. glycines and Pseudomonas syringae pv. syringae) using differential display reverse transcription polymerase chain reaction (DDDRT-PCR) technique. Reverse Northern and Northern blot analyses revealed that 50% of those genes were differentially expressed in pepper loaves during non-host resistance response. Among them, independent genes without redundancy were micro-arrayed for further analysis. Random EST sequence database were also generated from various CDNA libraries including pepper tissue specific libraries and leaves showing non-host hypersensitive response against X. campestris pv. glycines. As a primary stage, thousands of cDNA clones were sequenced and EST data were analyzed. These clones are being spotted on glass slide to study the expression profiling. Results of this study may further broaden knowledge on plant-pathogen interactions.

Xanthomonas euvesicatoria Causes Bacterial Spot Disease on Pepper Plant in Korea

  • Kyeon, Min-Seong;Son, Soo-Hyeong;Noh, Young-Hee;Kim, Yong-Eon;Lee, Hyok-In;Cha, Jae-Soon
    • The Plant Pathology Journal
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    • v.32 no.5
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    • pp.431-440
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    • 2016
  • In 2004, bacterial spot-causing xanthomonads (BSX) were reclassified into 4 species-Xanthomonas euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri. Bacterial spot disease on pepper plant in Korea is known to be caused by both X. axonopodis pv. vesicatoria and X. vesicatoria. Here, we reidentified the pathogen causing bacterial spots on pepper plant based on the new classification. Accordingly, 72 pathogenic isolates were obtained from the lesions on pepper plants at 42 different locations. All isolates were negative for pectolytic activity. Five isolates were positive for amylolytic activity. All of the Korean pepper isolates had a 32 kDa-protein unique to X. euvesicatoria and had the same band pattern of the rpoB gene as that of X. euvesicatoria and X. perforans as indicated by PCR-restriction fragment length polymorphism analysis. A phylogenetic tree of 16S rDNA sequences showed that all of the Korean pepper plant isolates fit into the same group as did all the reference strains of X. euvesicatoria and X. perforans. A phylogenetic tree of the nucleotide sequences of 3 housekeeping genes-gapA, gyrB, and lepA showed that all of the Korean pepper plant isolates fit into the same group as did all of the references strains of X. euvesicatoria. Based on the phenotypic and genotypic characteristics, we identified the pathogen as X. euvesicatoria. Neither X. vesicatoria, the known pathogen of pepper bacterial spot, nor X. perforans, the known pathogen of tomato plant, was isolated. Thus, we suggest that the pathogen causing bacterial spot disease of pepper plants in Korea is X. euvesicatoria.

Roles of Plant Proteases in Pathogen Defense

  • Baek, Kwang-Hyun;Choi, Do-Il
    • The Plant Pathology Journal
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    • v.24 no.4
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    • pp.367-374
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    • 2008
  • The genomes of plants contain more than 600 genes encoding a diverse set of proteases and the subunits of proteasomes. These proteases and proteasomes consist of plant proteolytic systems, which are involved in various cellular metabolic processes. Plant proteolytic systems have been shown to have diverse roles in defense responses, such as execution of the attack on the invading organisms, participation in signaling cascades, and perception of the invaders. In order to provide a framework for illustrating the importance of proteolytic systems in plant defense, characteristics of non-proteasome proteases and the 26S proteasome are summarized. The involvement of caspase-like proteases, saspases, apoplastic proteases, and the 26S proteasome in pathogen defense suggests that plant proteolytic systems are essential for defense and further clarity on the roles of plant proteases in defense is challenging but fundamentally important to understand plant-microbe interactions.

Isolation and Characterization of Pathogen-Inducible Putative Zinc Finger DNA Binding Protein from Hot Pepper Capsicum annuum L.

  • Oh, Sang-Keun;Park, Jeong-Mee;Jung, Young-Hee;Lee, Sanghyeob;Kim, Soo-Yong;Eunsook Chung;Yi, So-Young;Kim, Young-Cheol;Seung, Eun-Soo
    • Proceedings of the Korean Society of Plant Pathology Conference
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    • pp.79.2-80
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    • 2003
  • To better understand plant defense responses against pathogen attack, we identified the transcription factor-encoding genes in the hot pepper Capsicum annuum that show altered expression patterns during the hypersensitive response raised by challenge with bacterial pathogens. One of these genes, Ca1244, was characterized further. This gene encodes a plant-specific Type IIIA - zinc finger protein that contains two Cys$_2$His$_2$zinc fingers. Ca1244 expression is rapidly and specifically induced when pepper plants are challenged with bacterial pathogens to which they are resistant. In contrast, challenge with a pathogen to which the plants are susceptible only generates weak Ca1244 expression. Ca1244 expression is also strongly induced in pepper leaves by the exogenous application of ethephon, an ethylene releasing compound. Whereas, salicylic acid and methyl jasmonate had moderate effects. Pepper protoplasts expressing a Ca1244-smGFP fusion protein showed Ca1244 localizes in the nucleus. Transgenic tobacco plants overexpressing Ca1244 driven by the CaMV 355 promoter show increased resistance to challenge with a tobacco-specific bacterial pathogen. These plants also showed constitutive upregulation of the expression of multiple defense-related genes. These observations provide the first evidence that an Type IIIA - zinc finger protein, Ca1244, plays a crucial role in the activation of the pathogen defense response in plants.

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