• 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.

• The Plant Pathology Journal
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• v.24 no.2
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• pp.101-111
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• 2008

The fungal genus Alternaria is comprised of many saprophytic and endophytic species, but is most well known as containing many notoriously destructive plant pathogens. There are over 4,000 Alternaria/host associations recorded in the USDA Fungal Host Index ranking the genus 10th among nearly 2,000 fungal genera based on the total number of host records. While few Alternaria species appear to have a sexual stage to their life cycles, the majority lack sexuality altogether. Many pathogenic species of Alternaria are prolific toxin producers, which facilitates their necrotrophic lifestyle. Necrotrophs must kill host cells prior to colonization, and thus these toxins are secreted to facilitate host cell death often by triggering genetically programmed apoptotic pathways or by directly causing cell damage resulting in necrosis. While many species of Alternaria produce toxins with rather broad host ranges, a closely-related group of agronomically important Alternaria species produce selective toxins with a very narrow range often to the cultivar level. Genes that code for and direct the biosynthesis of these host-specific toxins for the Alternaria alternata sensu lato lineages are often contained on small, mostly conditionally dispensable, chromosomes. Besides the role of toxins in Alternaria pathogenesis, relatively few genes and/or gene products have been identified that contribute to or are required for pathogenicity. Recently, the completion of the A. brassicicola genome sequencing project has facilitated the examination of a substantial subset of genes for their role in pathogenicity. In this review, we will highlight the role of toxins in Alternaria pathogenesis and the use of A. brassicicola as a model representative for basic virulence studies for the genus as a whole. The current status of these research efforts will be discussed.

• Journal of Applied Biological Chemistry
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• v.42 no.1
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• pp.45-47
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• 1999

Two phytotoxic compounds were isolated from a culture of Exserohilum monoceras Inu-1, a fungal pathogen of Barnyard grass. The structure was determined by spectroscopic analyses including 2D NMR experiments. During the isolation procedure, the toxic components were monitored by the assay using Italian ryegrass (Lolium multiflorum Lam.), a host plant of the pathogen. The compounds inhibited the root growth of the host plant seedlings at a level of 100 ppm. While no substantial inhibition was observed even at 300 ppm in non-host plant seedlings such as lettuce and tomato.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.27-27
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• 2015

Clubroot (Plasmodiophora brassicae) is a serious agricultural problem affecting Brassica crop production worldwide. It also infects the model plant Arabidopsis thaliana. During infection, this biotrophic pathogen manipulates the development and metabolism of its host leading to the development of galls in the root and hypocotyl. In turn, its own development is strongly influenced by the host. The aim of this study is to investigate the metabolism of clubroot-infected plants using a combination of transcriptomic and metabolomic approaches. We have used direct injection mass spectrometry to obtain a metabolic fingerprint of when changes in the metabolome occur and linked this with changes in host and pathogen gene expression. We have identified alterations in carbohydrate metabolism that occur during P. brassicae infection of A. thaliana plants. Transcriptomic analysis showed that host genes associated with sugar transport and metabolism were induced during gall formation and that the pathogen also expresses genes associated with these processes. We have examined the impact of inactivating host sucrose synthase, cytosolic invertase and sugar permeases on gall formation, identifying host genes that are required for gall formation. We have also explored how sugar status is changed in root tissue, developing and mature leaf during infection of wild type and mutant plants.

• The Plant Pathology Journal
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• v.28 no.3
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• pp.322-329
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• 2012

This study was conducted to investigate host and non-host disease resistances of kimchi cabbage plants to bacterial infection. Kimchi cabbage leaves responded differently to infections with a virulent strain of Xanthomonas campestris pv. campestris (Xcc) 8004 and two strains (85-10 and Bv5-4a.1) of non-host bacteria X. campestris pv. vesicatoria (Xcv). Non-host bacteria triggered a rapid tissue collapse of the leaves showing as brown coloration at the infected sites, highly increased ion leakage, lipid peroxidation and accumulation of UV-stimulated autofluorescence materials at the inoculated sites. During the observed interactions, bacterial proliferations within the leaf tissues were significantly different. Bacterial number of Xcc 8004 progressively increased within the inoculated leaf tissues over time, while growths of two non-host bacteria Xcv strains were distinctly limited. Expressions of pathogenesis-related genes, such as GST1, PR1, BGL2, VSP2, PR4 and LOX2, were differentially induced by host and non-host bacterial infections of X. campestris pathovars. These results indicated that rapid host cellular responses to the non-host bacterial infections may contribute to an array of defense reactions to the non-host bacterial invasion.

• The Plant Pathology Journal
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• v.31 no.3
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• pp.299-304
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• 2015

Interaction of the the rust fungus Puccinia miscanthi with the biofuel plant Miscanthus sinensis during the teliospore phase was investigated by light and electron microscopy. P. miscanthi telia were oval-shaped and present on both the adaxial and abaxial leaf surfaces. Teliospores were brown, one-septate (two-celled), and had pedicels attached to one end. Transmission electron microscopy revealed numerous electron-translucent lipid globules in the cytoplasm of teliospores. Extensive cell wall dissolution around hyphae was not observed in the host tissues beneath the telia. Hyphae were found between mesophyll cells in the leaf tissues as well as in host cells. Intracellular hyphae, possibly haustoria, possessed electron-dense fungal cell walls encased by an electron-transparent fibrillar extrahaustorial sheath that had an electron-dense extrahaustorial membrane. The infected host cells appeared to maintain their membrane-bound structures such as nuclei and chloroplasts. These results suggest that the rust fungus maintains its biotrophic phase with most mesophyll cells of M. sinensis. Such a nutritional mode would permit the rust fungus to obtain food reserves for transient growth in the course of host alteration.

• Mycobiology
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• v.43 no.4
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• pp.444-449
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• 2015

Arbuscular mycorrhizal fungi (AMF) are ubiquitous in the rhizosphere and form symbiotic relationships with most terrestrial plant roots. In this study, four strains of Rhizophagus clarus were cultured and variations in their growth characteristics owing to functional diversity and resultant effects on host plant were investigated. Growth characteristics of the studied R. clarus strains varied significantly, suggesting that AMF retain high genetic variability at the intraspecies level despite asexual lineage. Furthermore, host plant growth response to the R. clarus strains showed that genetic variability in AMF could cause significant differences in the growth of the host plant, which prefers particular genetic types of fungal strains. These results suggest that the intraspecific genetic diversity of AMF could be result of similar selective pressure and may be expressed at a functional level.

• The Plant Pathology Journal
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• v.37 no.5
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• pp.494-501
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• 2021

Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However, the function of these effectors, including avirulence protein E1 (AvrE1), in the pathogenicity of P. cichorii, remains unexplored. In this study, to investigate the function of avrE1 in P. cichorii JBC1 (PcJBC1), we created an avrE1-deficient mutant (JBC1^ΔavrE1) using CRISPR/Cas9. The disease severity caused by JBC1^ΔavrE1 in tomato plants significantly decreased by reducing water soaking during early infection stage, as evidenced by the electrolyte leakage in infected leaves. The disease symptoms caused by JBC1^ΔavrE1 in the cabbage midrib were light-brown spots compared to the dark-colored ones caused by PcJBC1, which indicates the role of AvrE1 in cell lysis. The avrE1-deficient mutant failed to elicit cell death in non-host tobacco plants. Disease severity and cell death caused by JBC1^ΔavrE1 in host and non-host plants were restored through heterologous complementation with avrE1 from Pseudomonas syringae pv. tomato DC3000 (PstDC3000). Overall, our results indicate that avrE1 contributes to cell death during early infection, which consequently increases disease development in host plants. The roles of PcJBC1 AvrE1 in host cells remain to be elucidated.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.363-380
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• 2019

Previous studies on the host plant range of Metcalfa pruinosa were conducted without distinguishing between its stages of development. In this study, we investigated host plants by studying the nymph and adult development stages of M. pruinosa. M. pruinosa nymphs were found on host plants that belong to 78 families and 227 species, and, to the best of our knowledge, host plants that belong to 27 families and 38 species have been reported for the first time. The host plants were divided into woody and herbaceous at the nymph stage of M. pruinosa, and the nymphs were found in 110 herbaceous and 117 woody species. M. pruinosa adults were found on host plants that belong to 87 families and 233 species, and, host plants that belong to 26 families and 36 species have been reported for the first time. The host plants were divided into woody and herbaceous at the adult stage of M. pruinosa, and the adults were found in 105 herbaceous and 128 woody species. Therefore, the total domestic host plant of M. pruinosa was 98 families 345 species. The nymph and adult in preoviposition stage prefer Helianthus annuus and the adult in oviposition stage prefer Persicaria tinctoria and Rosa rugosa.

• Korean Journal of Veterinary Service
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• v.42 no.2
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• pp.73-83
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• 2019

Foot-and-Mouth Disease (FMD) is a highly contagious trans-boundary viral disease caused by FMD virus, which causes huge economic losses. FMDV infects cloven hoofed (two-toed) mammals such as cattle, sheep, goats, pigs and various wildlife species. To control the FMDV, it is necessary to understand the life cycle and the pathogenesis of FMDV in host. Especially, the protein-protein interaction between FMDV and host will help to understand the survival cycle of viruses in host cell and establish new therapeutic strategies. However, the computational approach for protein-protein interaction between FMDV and pig hosts have not been applied to studies of the onset mechanism of FMDV. In the present work, we have performed the prediction of the pig's proteins which interact with FMDV based on RNA-Seq data, protein sequence, and structure information. After identifying the virus-host interaction, we looked for meaningful pathways and anticipated changes in the host caused by infection with FMDV. A total of 78 proteins of pig were predicted as interacting with FMDV. The 156 interactions include 94 interactions predicted by sequence-based method and the 62 interactions predicted by structure-based method using domain information. The protein interaction network contained integrin as well as STYK1, VTCN1, IDO1, CDH3, SLA-DQB1, FER, and FGFR2 which were related to the up-regulation of inflammation and the down-regulation of cell adhesion and host defense systems such as macrophage and leukocytes. These results provide clues to the knowledge and mechanism of how FMDV affects the host cell.