• The Plant Pathology Journal
• /
• v.17 no.2
• /
• pp.83-87
• /
• 2001

Disease resistance in plants is often controlled by gene-for-gene mechanism in which avirulence (avr) gene products encoding by pathogens are specifically recognized, either directly or indirectly by plant disease resistance (R) gene products. Recent studies arising from molecular cloning of a number of R genes from various plant species that confer resistance to different pathogens and corresponding avr genes from various pathogens resulted in the accumulation of a wealth of knowledge on mode of action of gene-for-gene interaction. Specially, members of the NBS-LRR class of R genes encoding proteins containing a nucleotide binding site (NBS) and carboxyl-terminal leucine-rich repeats (LRRs) confer resistance to very different types of phytopathogens, such as bacteria, fungi, oomycetes, viruses, nematodes and aphids. This article reviewed the molecular events that occur up-stream of defense response pathway, specially, bacterial avr gene protein recognition mediated by NBS-LRR type R gene product in plant based on current research results of well studied model plants.

• Journal of Plant Biotechnology
• /
• v.32 no.2
• /
• pp.73-83
• /
• 2005

Disease resistance in plants is often controlled by gene-for-gene mechanism in which avirulence (avr) gene products encoding by pathogens are specifically recognized, either directly or indirectly by plant disease resistance (R) gene products and sequential signal transduction pathways activating defense responses are rapidly triggered. As a results, not only exhibit a resistance against invading pathogens but also plants maintain the systemic acquired resistance (SAR) to various other pathogens. This molecular interaction between pathogen and plant is commonly compared to innate immune system of animal. Recent studies arising from molecular characterization of a number of R genes from various plant species that confer resistance to different pathogens and corresponding avr genes from various pathogens resulted in the accumulation of a wealth of knowledge on molecular mechanism of gene-for-gene interaction. Furthermore, new technologies of genomics and proteomics make it possible to monitor the genome-wide gene regulation and protein modification during activation of disease resistance, expanding our ability to understand the plant immune response and develop new crops resistant to biotic stress.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.1
• /
• pp.130-137
• /
• 2007

A disease resistance related gene, MbR7, was identified in the wild apple species, Malus baccata. The MbR7 gene has a single open reading frame (ORF) of 3,288 nucleotides potentially encoding a 1,095-amino acid protein. Its deduced amino acid sequence resembles the N protein of tobacco and the NL27 gene of potato and has several motifs characteristic of a TIR-NBS-LRR R gene subclass. Ectopic expression of MbR7 in Arabidopsis enhanced the resistance against a virulent pathogen, Pseudomonas syringae pv. tomato DC3000. Microarray analysis confirmed the induction of defense-related gene expression in 35S::MbR7 heterologous Arabidopsis plants, indicating that the MbR7 gene likely activates a downstream resistance pathway without interaction with pathogens. Our results suggest that MbR7 can be a potential target gene in developing a new disease-resistant apple variety.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.201-201
• /
• 2022

Rice bakanae disease is a serious global threat in major rice-cultivating regions worldwide causing high yield loss. It is caused by the fungal pathogen Fusarium fujikuroi. Varying degree of resistance or susceptibility to bakanae disease had been reported among Korean japonica rice varieties. We developed a modified in vitro bakanae disease bioassay method and tested 31 Korean japonica rice varieties. Nampyeong and Samgwang varieties showed highest resistance while 14 varieties including Junam and Hopum were highly susceptible with 100% mortality rate. We carried out mapping QTLs for bakanae disease resistance with four F2:F3 populations derived from the crosses between Korean japonica rice varieties. The Kompetitive Allele-Specific PCR (KASP) markers developed in our laboratory based on the SNPs detected in Korean japonica rice varieties were used in genotyping F2 plants in the populations. We found four major QTLs on chromosome 1, 4, 6, and 9 with LOD scores of 21.4, 6.9, 6.0, and 60.3, respectively. In addition, we are doing map-based cloning of the QTLs on chromosome 1 and 9 which were found with Junam/Nampyeong F2:F3 population and Junam/Samgwang F2:F3 population, respectively. These QTLs will be very useful in developing bakanae disease resistant high quality rice varieties.

• The Plant Pathology Journal
• /
• v.28 no.4
• /
• pp.364-372
• /
• 2012

Xanthomonas oryzae pv. oryzae causing bacterial leaf blight disease in rice produces and secretes Hpa1 protein that belongs to harpin protein family. Previously it was reported that Hpa1 induced defense responses when it was produced in tobacco. In this study, we expressed hpa1 gene in rice and Arabidopsis to examine the effects of Hpa1 expression on disease resistance to both fungal and bacterial pathogens. Expression of hpa1 gene in rice enhanced disease resistance to both X. oryzae pv. oryzae and Magnaporthe grisea. Interestingly, individual transgenic rice plants could be divided into four groups, depending on responses to both pathogens. hpa1 expression in Arabidopsis also enhanced disease resistance to both Botrytis cineria and Xanthomonas campestris pv. campestris. To examine genes that are up-regulated in the transgenic rice plants after inoculation with X. oryzae pv. oryzae, known defense-related genes were assessed, and also microarray analysis with the Rice 5 K DNA chip was performed. Interestingly, expression of OsACS1 gene, which was found as the gene that showed the highest induction, was induced earlier and stronger than that in the wild type plant. These results indicate that hpa1 expression in the diverse plant species, including monocot and dicot, can enhance disease resistance to both fungal and bacterial plant pathogens.

• Molecules and Cells
• /
• v.26 no.3
• /
• pp.258-264
• /
• 2008

A rice diacylglycerol kinase (DGK) gene, OsBIDK1, which encodes a 499-amino acid protein, was cloned and characterized. OsBIDK1 contains a conserved DGK domain, consisting of a diacylglycerol kinase catalytic subdomain and a diacylglycerol kinase accessory subdomain. Expression of OsBIDK1 in rice seedlings was induced by treatment with benzothiadiazole (BTH), a chemical activator of the plant defense response, and by infection with Magnaporthe grisea, causal agent of blast disease. In BTH-treated rice seedlings, expression of OsBIDK1 was induced earlier and at a higher level than in water-treated control seedlings after inoculation with M. grisea. Transgenic tobacco plants that constitutively express the OsBIDK1 gene were generated and disease resistance assays showed that overexpression of OsBIDK1 in transgenic tobacco plants resulted in enhanced resistance against infection by tobacco mosaic virus and Phytophthora parasitica var. nicotianae. These results suggest that OsBIDK1 may play a role in disease resistance responses.

• Korean Journal of Agricultural Science
• /
• v.48 no.1
• /
• pp.151-161
• /
• 2021

Fusarium wilt disease of tomato plants caused by Fusarium oxysporum f.sp. lycopersici (FOL race2) is one of the most important diseases of tomatoes worldwide. In the competition between tomato and FOL, the FOL can win by overcoming the immune system of tomato plants. Resistant interaction between the FOL race2 and tomato plants is controlled by avirulence genes (AVR2) in FOL and the corresponding resistance genes (I2) in tomato plants. In this study, 7 FOL isolates (KACC) were used to test their pathogenicity, and FOL race2 was selected because it is a broad problem in Korea. The Fol40044 isolates showed the most severe pathogenicity, and the avr2 gene was also isolated and identified. Moreover, to select resistance, 20 tomato varieties were inoculated with the Fol40044, and the degree of pathogenicity was evaluated by analyzing the expression of the avr2 gene. As a result, three resistant tomato varieties (PCNUF73, PCNUF101, PCNUF113) were selected, and the expression of the avr2 gene was much lower than that of the control Heinz cultivar. This result shows that the screening assay is very efficient when the avr2 gene is used as a marker to evaluate the expression level when selecting varieties resistant to tomato wilt disease. Based on these results, it is possible to isolate the I2 gene, which exhibits resistance and molecular biological interactions with the AVR2 gene from the three tomato-resistant varieties. The I2 gene provides breeders more opportunities for Fusarium disease resistance and may contribute to our understanding of their interactions with the FOL and host plant.

• BMB Reports
• /
• v.51 no.2
• /
• pp.55-56
• /
• 2018

Long terminal repeat retrotransposons (LTR-Rs) are major elements creating new genome structure for expansion of plant genomes. However, in addition to the genome expansion, the role of LTR-Rs has been unexplored. In this study, we constructed new reference genome sequences of two pepper species (Capsicum baccatum and C. chinense), and updated the reference genome of C. annuum. We focused on the study for speciation of Capsicum spp. and its driving forces. We found that chromosomal translocation, unequal amplification of LTR-Rs, and recent gene duplications in the pepper genomes as major evolutionary forces for diversification of Capsicum spp. Specifically, our analyses revealed that the nucleotide-binding and leucine-rich-repeat proteins (NLRs) were massively created by LTR-R-driven retroduplication. These retoduplicated NLRs were abundant in higher plants, and most of them were lineage-specific. The retroduplication was a main process for creation of functional disease-resistance genes in Solanaceae plants. In addition, 4-10% of whole genes including highly amplified families such as MADS-box and cytochrome P450 emerged by the retroduplication in the plants. Our study provides new insight into creation of disease-resistance genes and high-copy number gene families by retroduplication in plants.

• Journal of Crop Science and Biotechnology
• /
• v.11 no.2
• /
• pp.101-106
• /
• 2008

To identify inheritance of clubroot disease resistance genes in Chinese cabbage, seedling tests of $BC_1P_1,\;BC_1P_2$, and $F_2$ populations derived from $F_1$ hybrid(var. CR Saerona) using single spore isolate(race 4 identified with William's differential host) from Plasmodiophora brassciae were conducted. Resistance(R) and susceptible(S) plants segregated to 1:0 in backcross to the resistant parent. The $F_2$ population segregated in a 3(R):1(S) ratio. This result implied that the resistance of clubroot disease is controlled by a single dominant gene to the race 4 of P. brassicae in CR Saerona. To develop DNA markers linked to clubroot resistance genes, 185 plants of CR Saerona among $F_2$ populations were used. A total of 300 arbitrary decamer was applied to $F_2$ population using BSARAPD(Bulked segregant analysis-Randomly amplified polymorphic DNA). One RAPD marker linked to clubroot resistance gene in CR Saerona($OPJ_{1100}$) was identified. This marker was 3.1 cM in distance from resistance gene in $F_2$ population. This marker may be useful for a marker-assisted selection(MAS) and gene pyramiding of the clubroot disease resistant gene in Chinese cabbage breeding programs.

• Korean Journal of Veterinary Research
• /
• v.55 no.3
• /
• pp.191-197
• /
• 2015

Escherichia (E.) coli is commensal bacteria found in the intestine; however, some pathogenic strains cause diseases in animals and humans. Although E. coli does not typically produce hydrogen sulfide ($H_2S$), $H_2S$-producing strains of E. coli have been identified worldwide. The relationship between virulence and $H_2S$ production has not yet been determined. Therefore, characteristics of $H_2S$-producing isolates obtained from swine feces were evaluated including antibiotic resistance patterns, virulence gene expression, and genetic relatedness. Rates of antibiotic resistance of the $H_2S$-producing E. coli varied according to antibiotic. Only the EAST1 gene was detected as a virulence gene in five $H_2S$-producing E. coli strains. Genes conferring $H_2S$ production were not transmissible although the sseA gene encoding 3-mercaptopyruvate sulfurtransferase was detected in all $H_2S$-producing E. coli strains. Sequences of the sseA gene motif CGSVTA around Cys238 were also identical in all $H_2S$- producing E. coli strains. Diverse genetic relatedness among the isolates was observed by pulsed-field gel electrophoresis analysis. These results suggested that $H_2S$-producing E. coli strains were not derived from a specific clone and $H_2S$ production in E. coli is not associated with virulence genes.