• The Plant Pathology Journal
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• 제35권1호
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• pp.84-89
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• 2019

Two-component systems (TCSs) are critical to the pathogenesis of Xanthomonas oryzae pv. oryzae (Xoo). We mutated 55 of 62 genes annotated as responsive regulators (RRs) of TCSs in the genome of Xoo strain PXO99A and identified 9 genes involved in Xoo virulence. Four (rpfG, hrpG, stoS, and detR) of the 9 genes were previously reported as key regulators of Xoo virulence and the other 5 have not been characterized. Lesion lengths on rice leaves inoculated with the mutants were shorter than those of the wild type and were significantly restored with gene complementation. The population density of the 5 mutants in planta was smaller than that of PXO99A at 14 days after inoculation, but the growth curves of the mutants in rich medium were similar to those of the wild type. These newly reported RR genes will facilitate studies on the function of TCSs and of the integrated regulation of TCSs for Xoo pathogenesis.

• Applied Biological Chemistry
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• 제48권4호
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• pp.339-344
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• 2005

도열병은 곰팡이 균(Magnaporthe grisea)에 의해 발병되는 것으로, 벼 수확량에 가장 큰 손실을 일으킨다. 본 연구에서는 벼 도열병 저항성 신호전달 체계에 관여하는 유전자를 분리하기 위하여 DEB(1, 3-Butadiene diepoxide) 처리를 통하여 벼 도열병 저항성 품종인 RIl260의 돌연변이 2,000여 종을 생산하고, 이들로부터 병 저항성 변이 개체를 조사하였다. 돌연변이 집단에서 백변종 돌연변이의 비율은 6.7%로 매우 높았으며, 이것은 DEB 처리에 의해서 생산된 집단 내에 돌연변이가 높은 빈도로 발생하였음을 보여준다. 돌연변이 집단의 병 저항성 분석을 통하여 완전히 혹은 부분적으로 벼 도열병에 저항성을 상실한 29개의 돌연변이체를 분리하였다. 이들 중에서 가장 심한 이병성 라인으로 확인된 M5465는 DNA 혼성화 반응 분석을 사용하여 분석하였으며, RIL260 품종에서 도열병 병 저항성과 밀접한 관련을 갖고 있는 것으로 보고된 Pi5(t) 유전좌위의 DNA 표지들이 실험에 사용되었다. 이 결과들은 M5465에서 Pi5(t) 유전좌위 내부에 DNA의 큰 결손 및 재배열이 있었음을 보여준다. 분리된 병 저항성 돌연변이 라인들은 Pi5(t)에 의해 매개된 도열병 저항성의 신호 전달 과정을 이해하는 데 유용하게 사용 될 수 있을 것이다.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2004년도 춘계학술대회
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• pp.65-65
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• 2004

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 춘계학술대회 및 임시총회
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• pp.13-13
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• 2015

Rice blast fungus, Magnaporthe oryzae, is the most destructive pathogen of rice in the world. This fungus has a biotrophic phase early in infection and switches to a necrotrophic lifestyle after host cell death. During the biotrophic phase, the fungus competes with host for nutrients and oxygen. Continuous uptake of oxygen is essential for successful establishment of blast disease of this pathogen. Here, we report transcriptional responses of the fungus to oxygen limitation. Transcriptome analysis using RNA-Seq identified 1,047 up-regulated genes in response to hypoxia. Those genes were involved in mycelial development, sterol biosynthesis, and metal ion transport based on hierarchical GO terms and well-conserved among three different fungal species. In addition, null mutants of three hypoxia-responsive genes were generated and tested for their roles on fungal development and pathogenicity. The mutants for a sterol regulatory element-binding protein gene, MoSRE1, and C4 methyl sterol oxidase gene, ERG25, exhibited increased sensitivity to hypoxia-mimetic agent, increased conidiation, and delayed invasive growth within host cells, suggesting important roles in fungal development. However, such defects did not cause any significant decrease in disease severity. The other null mutant for alcohol dehydrogenase gene, MoADH1, showed no defect in the hypoxia-mimic condition and fungal development. Taken together, this comprehensive transcriptional profiling in response to a hypoxia condition with experimental validations would provide new insights on fungal development and pathogenicity in plant pathogenic fungi.

• Journal of Crop Science and Biotechnology
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• 제11권4호
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• pp.237-242
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• 2008

A liguleless mutant, which showed complete loss of lamina joint region at the junction between leaf blade and leaf sheath, was isolated from a Ds insertional mutants derived from the source cultivar, Dongjin. This mutant could not affect other developmental patterns like phyllotaxis. Southern blot analysis, using GUS as a probe, revealed that the liguleless mutant contained three Ds copies transposed in the rice genome. Among the four genomic sequences flanking the Ds, one was mapped in the intergenic region (31661640 - 31661759), and the other two predicted a protein kinase domain (12098980 - 12098667) as an original insertion site within a starter line used for massive production of Ds insertional mutant lines. Another predicted and inserted in first exon of liguleless 1 protein (OsLG1) that was mapped in coding region (LOC_Os04g56170) of chromosome 4. RT-PCR revealed that the OsLG1 gene was not expressed liguleless mutants. Structure analysis of OsLG1 protein revealed that it predicted transcription factor with a highly conserved SBP domain consisting of 79 amino acids that overlapped a nuclear localization signal (NLS). RT-PCR revealed that OsLG1 is mainly expressed in vegetative organs.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.43-43
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• 2018

Mutation breeding by radiation is useful for improving various crop species. Up to now, a total of 170 soybean mutant varieties have been released in the world, which is the second most registered varieties after rice. Despite the economic importance of soybean, there have been no TRAP marker system studies on genetic relationships between/among mutant lines. To develop a strategy of Mutant Diversity Pool (MDP) conservation, a study on the genetic diversity of 210 soybean mutant lines (8 cultivars and 202 mutants) was performed through a TRAP analysis. Sixteen primer combinations amplified a total of 551 fragments. The highest (84.00%) and lowest (32.35%) polymorphism levels were obtained with primers MIR157B + Ga5 and B14G14B + Ga3, respectively. The mean PIC values 0.15 varied among the primer combination ranging from 0.07 in B14G14B + Sal2 to 0.23 in MIR157B + Sa4. Phylogenetic, principal component analysis (PCA) and structure analysis indicated that the 210 lines belong to four groups based on the 16 combination TRAP markers. AMOVA showed 21.0% and 79.0% variations among and within the population, respectively. Overall, the genetic similarity of each cultivar and its mutants were higher than within other mutant populations. Our results suggest that the TRAP marker system may be useful for assessing the genetic diversity among soybean mutants and help to improve our knowledge of soybean mutation breeding.

• 한국자원식물학회지
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• 제20권5호
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• pp.389-397
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• 2007

벼의 캘러스를 대상으로 Tos17 활성 증가를 이용하여 새로운 돌연변이체의 유발 및 선발에 대한 연구는 많이 시도되어 왔다. 일품벼에서 배양된 캘러스를 이용하여 배양기간 및 배양조건에 따른 retrotransposon(Tos17)의 활성화를 유도함을 일차적인 목적으로 하고, 이에 따른 재분화 개체를 통하여 다양한 돌연변이체($M_1$)를 얻음과 동시에 세대의 진전에 따른 돌연변이체($M_2$, $M_3$)가 나타내는 표현형과 Tos17과의 연관성을 확인하여 특정 유전자의 cloning을 향후 목적으로 하고 있다. 1. 본 연구에서는 배양기간에 따라 총 371개체의 $M_1$ 돌연변이체를 얻었다. 2. 각각의 배양기간 단계별 재분화 식물체에서 얻어진 Tos17의 활성정도를 나타내는 Southern blot의 결과 normal 즉, 기본 식물인 일품벼는 5개의 copy수를 가지고 있는 것을 알 수 있었으며, 1개월 7개, 2개월 8개, 3개월 9.5개, 5개월 12개, 6개월 6개, 7개월 13.5개, 8개월 17.5개의 band를 확인할 수 있었다. 3. Tos17의 Southern blot의 결과, $3{\sim}5$개월의 배양기간이 경과해야만 기본 copy의 2배수로 Tos17이 활성화됨을 알 수 있었다. 향후 $M_1$돌연변이체의 세대진전을 통하여 $M_2$, $M_3$ 세대 등의 다양한 재조합 개체의 확보 및 분석이 중요하다. 또한 다양한 형태로 원하는 돌연변이를 선발하는 screening 방법을 개발하는 것이 시급하고 중요한 과제이다.

• Plant Breeding and Biotechnology
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• 제6권4호
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• pp.313-320
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• 2018

Rice is the staple food of more than 50% of the world population. Cultivated rice has the AA genome (diploid, 2n = 24) and small genome size of only 430 megabase (haploid genome). As the sequencing of rice genome was completed by the International Rice Genome Sequencing Project (IRGSP), many researchers in the world have been working to explore the gene function on rice genome. Insertional mutagenesis has been a powerful strategy for assessing gene function. In maize, well characterized transposable elements have traditionally been used to clone genes for which only phenotypic information is available. In rice endogenous mobile elements such as MITE and Tos have been used to generate gene-tagged populations. To date T-DNA and maize transposable element systems have been utilized as main insertional mutagens in rice. The Ac/Ds system offers the advantage of generating new mutants by secondary transposition from a single tagged gene. To enhance the efficiency of gene detection, advanced gene-tagging systems (i.e. activation, gene or enhancer trap) have been employed for functional genomic studies in rice. Internationally, there have been many projects to develop large scales of insertional mutagenized populations and databases of insertion sites has been established. Ultimate goals of these projects are to supply genetic materials and informations essential for functional analysis of rice genes and for breeding using agronomically important genes. In this report, we summarize the current status of Ac/Ds-mediated gene tagging systems that has been conducted by collaborative works in Korea.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.134-134
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• 2017

Recently, host-induced gene silencing (HIGS) system has been successfully applied into development of resistant crops against insects, fungal and viral pathogens. To test HIGS-mediated resistance in rice against rice blast fungus, Magnaporthe oryzae, we first tested possibility of movement of small non-coding RNA from rice cells to rice blast fungus. The rice blast fungus expressing GFP transgene were inoculated to transgenic rice plants ectopically expressing dsRNAi construct targeting fungal GFP gene. Expression of dsRNAi construct for GFP gene in transgenic plants significantly suppressed GFP expression in infected fungal cells indicating that small RNAs generated in plant cells can move into infected fungal cells and efficiently suppress the expression of fungal GFP gene. Consistent with these results, expression of dsRNAi constructs against 3 fungal pathogenic genes of M. oryzae in transgenic rice specifically and efficiently suppressed not only the expression of fungal pathogenic genes, but also fungal infection. The conidia of M. oryzae applied on leaf sheath of transgenic rice expressing dsRNAs against 3 fungal pathogenic genes showed abnormal development of primary hyphae and malfunction of appressorium, which is consistent with the phenotypes of corresponding fungal knock-out mutants. Taken these results together, here, we suggest a novel strategy for development of antifungal crops by means of HIGS system.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.82-83
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• 2003

Plants have evolved differently from animals having mobile activities. Thus, plants should have developed unique defense mechanisms against biotic/abiotic stresses to which plants are differently exposed, according to seasons. Most organisms have an conserved signaling network using mitogen-activated protein kinase (MAPK) cascade(s). The phenomenon implied that they are functionally very important in all organisms. In fact, they constitute one of the major components of signaling pathways involved in regulating a wide range of cellular activities from growth and development to cell death. Recently, complete MAPK cascade was first characterized in Arabidopsis from the receptor kinase (FLS2) through fellowing MEKKI -MKK4/MKK5-MPK3/MPK6-WRKY22/MRKY29 pathway. Whereas, MAPK cascade signaling pathway in monocot plant including rice (0ryza sativa L.), the most important of all food crops and an established monocot plant research model, MAPKinase kinase kinases (MAPKKK) of rice are the first upstream component of the MAPK cascade, but MAPKKK has been first identified and characterized in our lab and designated as, OsEDRl based on its homology with the Arabidopsis EDRI. The Arabidopsis EDRl was regarded as a negative regulator of defense response and the role of rice OsEDRl was analyzed. Transcriptional regulation of OsEDRl was detected under various stresses and immunoblotting analysis is going on to detect the level of OsEDRl protein in the mutants showing unique phenotype. We also introduced the constitutively active and the dominant negative forms of the OsEDRl for characterizing biological function.