Bacterial wilt (BW) caused by Ralstonia solanacearum is one of the most common soil-borne vascular diseases of many solanaceous crops such as pepper and tomato. This study aimed to develop molecular markers closely linked to bacterial wilt resistance genes using a 150 F8 recombinant inbred line (RIL) population obtained from a cross of ‘YCM334’ x ‘Taean’. For pathogen inoculations, R. solanacearum isolate WR-1 was cultured on NB medium at 28℃ for 48 h and a bacterial suspension was adjusted to 1 x 107 to 1 X 108 CFU/mL (A 600 = 0.3 to 0.4). Each RIL and the parents were sown in a 72-cell plastic tray filled with sterilized soil, and the seedlings were inoculated at the 6 to 8 leaf stage using soil-drenching (3 to 5 ml/ plant) inoculation methods with 3 replications. After 10 days post inoculation (dpi), each line was evaluated visually for occurrence of bacterial wilt ranging from 1 (most resistant) to 5 (most susceptible). Two candidate R-response genes, AT4G14130 and AT3G23730, were selected to find SNPs between YCM334 and Taean. In previous transcriptome analysis, these two genes were reported as significantly differentially expressed in Capsicum annuum L. root inoculated with R. solanacearum, which were up-regulated in a resistant genotype. Once the synteny of the gene locations between Arabidopsis and pepper was documented, the sequences on pepper chromosome 12 were obtained from pepper. v.1.55 (http://solgenomics.net). SNP markers associated with resistance to BW will be mapped using pepper RIL population.

Low temperature germinability (LTG) is an important trait for breeding of varieties for use in direct-seeding rice production systems. Although rice (Oryza sativa L.) is generally sensitive to low temperatures, genetic variation for LTG exists and several quantitative trait loci (QTLs) have been reported. The objective of this study was to develop and employ high-efficiency molecular markers for evaluation of LTG in rice germplasm. A panel of japonica rice accessions (n=180) from temperate regions in Asia was evaluated for LTG and genotyped with markers from regions previously reported to harbor other LTG QTLs. ANOVA revealed that four markers on chromosome 2, 4, and 11 from previously reported QTLs showed highly significant value (p < 1.0e-04) and their R2 ranged 0.083 (qLTG11-1) to 0.190 (qLTG4b-1). An association analysis was conducted using SNP data generated by sequencing of the panel. Eight SNP markers were found to be significantly associated with LTG using general and mixed linear models. Three SNP-based CAPS and dCAPS markers from these results were developed and showed higher accuracy in predicting sensitive LTG germplasm. These new LTG markers will be useful for molecular evaluation of germplasm, particularly to identify sensitive or weak LTG accessions.

Platycodon grandiflorum, which is the only species in the genus Platycodon of the family Campanulaceae, is an herbaceous flowering perennial. P. grandiflorum is generally known as bellflower or balloon flower indicating its ornamental uses. It has also been traditionally used as a medicinal crop in East Asia, which is widely employed as an antiphlogistic, antitussive, and expectorant. However, marker-assisted selection and molecular breeding in P. grandiflorum has lagged behind other plants such as pepper and tomato because of the lack of genetic information and effective molecular markers. Transcriptome sequencing provides an effective way to obtain large amount of sequence data when there is no available genome sequence. In this study, we performed a transcriptome analysis in platycodons, which has not been attempted previously. We analyzed simple sequence repeats (SSRs) using RNA-seq data. Di-nucleotide motifs were the most abundant repeats (39% ~ 40%) followed by mono- (26% ~ 32%), tri- (25% ~ 31%), tetra- (1.5% ~ 1.9 %), penta- (0.3% ~ 1%) in three platycodon accessions. Based on the SNP information obtained from RNA-seq analysis, we developed 12 PCR-based markers in Platycodon. The number of alleles ranged from two to seven with the average PIC value of 0.373. These 12 markers were applied to 21 platycodon accessions and a phylogenetic tree was constructed. The markers developed in this study could be introduced in molecular breeding program of platycodons. The SSR information obtained from RNA-seq analysis could be further utilized for developing genic-SSR markers in platycodons. Since platycodon is considered as an orphan crop, which has not been actively deployed for genetic study, the sequence information obtained from this study will contribute to further genetic improvements, genomic information and gene discovery in platycodon

Green rice leafhopper(GRH), Nephotettix cincticeps Uhier, is one of the major insect pests of rice (Oryza sativa L.) in the temperate growing region of East Asia. GRH sucks sap from both xylem and phoem of susceptible rice varieties, and increased GRH populations cause sooty mold disease on the ears of rice after heading stage. In addition to direct plant destruction, GRH also causes damage to rice plants by transmitting rice dwarf viruses causing rice dwarf viruses disease which could decrease the yield of rice. Development of GRH resistant rice varieties for reducing yield loss is an important objective in current breeding programs. In this study, we developed three SSR markers(RM18166, RM516, RM18171) and one Indel marker(Indel15040) which could select Grh1-resistant varieties using population derived from cross lines between Grh1-resistant variety ‘Singwang’ which contains Grh1 gene and susceptible variety ‘Ilpum’. PCR products of RM18166 which was one of the developed markers were easily detected in agarose gel. These markers will be useful for development of the Grh1-resistant varieties through marker-assisted selection(MAS) without bio-examination in rice breeding

식물연구에 있어 다양한 분자마커의 개발은 학문적 그리고 기술적으로 새로운 혁신을 가져왔다. DNA를 이용한 분자마커는 DNA 지문뿐만 아니라 식물의 분류학, 생리학 및 유전공학 등 다양한 분야에서 사용되고 있다. 밀은 옥수수, 벼와 함께 세계 중요 3대 작물 중 하나로서 17,000 Mb의 게놈을 가지고 있어 연구에 많은 어려움이 따르고 있다. 본 연구는 현재까지 보고된 분자마커를 이용한 밀 연구 분야에 관한 보고들을 분석하여 앞으로의 연구 방향을 제시하고자 하였다. 1990년부터 2012년까지 발표된 주요 논문 1,123편을 분석한 결과 유전육종 분야가 38.3%로 가장 높았으며, 분자표지인자와 생리학 분야가 각각 26.9%와 1.5%로 나타났다. 미국을 포함하여 중국, 호주 영국 등 4개국에서 발표한 논문이 전체의 50% 이상을 차지하고 있으며, 이들 국가소속기관 연구소에서 발표된 논문이 전체의 52%로서, 대학보다 활발히 진행되고 있는 것을 알 수 있었다. 특히 밀의 연구는 1992년부터 2007년까지 급격하게 증가하였는데 이것은 밀의 다양한 육종사업과 분자표지인자 기법의 발달이 영향을 미쳤기 때문이다. 그러나 국내 밀의 연구 논문은 88편으로 2008년 이후 대부분 보고되는 것으로 보아 밀의 연구가 매우 늦게 시작된 것을 알 수 있다. 현재까지 국내 밀의 연구는 유전육종 분야에 집중되어 있는 것을 알 수 있다. 국산 밀은 ‘금강’ 등 30 여 품종이 생산량 증가, 재해저항성 증진 등의 목적으로 육성되었다. 예를들어 백립계 제면용으로서 내한성과 붉은곰팡이 중도 저항성을 가지는 ‘한백’, ‘적중’, ‘알찬’, ‘수강’ 등의 품종이 개발되었다. 이와 같이 다양한 목적에 맞는 밀 품종이 육성되어 있기 때문에 이 후의 연구는 용도별 신품종 육성과 함께 국산 밀 품종을 보호하는 방향으로 나아가야할 것이다. 이를 위해선 국산 밀의 기본적인 식물적 특성과 유전적 특성이 확립되어야한다. 최근 국산 밀의 품질 및 품종 판별에 적합한 분자표지인자를 개발하기 위한 다양한 분석방법이 시도되고 있다. 다양한 분자표지인 자 기술 및 개발은 앞으로의 밀 육종사업에 유용한 도구로서 이용가치가 매우 높기 때문에 SSR, ISSR, STS 등의 분자표지인자를 개발하여 국내 밀품종을 보호할 뿐만 아니라, 밀의 수량성 및 고품질과 내재해성 등에 관련된 많은 연구를 통하여 밀의 품질과 수량성 향상에 이용해야 할 것이다.

In direct-seeding cultivation of rice, the emergence and establishment of seedlings are important for determining the actual yield. These traits depend principally upon elongation of both the mesocotyl and coleoptile. Mesocotyl elongation in rice is controlled by several genetic factors and is also affected by environmental factors. In this study, we mapped QTL for mesocotyl elongation using F8 lines from a cross between the cultivated rice, Ilpumbyeo and a weedy rice, PBR. One of the Korean weedy rice, PBR showed the long mesocotyl length than that of cultivars, Ilpumebyeo under soil and agar media conditions. This weedy rice showed long mesocotyl than the elite japonica cultivars. After a phenotyping of 150 F7 lines for mesocotyl length, a subset of 20 lines selected from the two extreme phenotypic tails was used for the bulked segregant analysis. Two QTL were identified on chromosomes 1 and 3. These two QTL were confirmed using 120 F8 lines. Two QTL, qMel-1 and qMel-3 on chromosomes 1 and 3 accounted for 37.3% and 6.5% of the phenotypic variance, respectively. The PBR alleles were associated with an increase in mesocotyl elongation at both loci. It is noteworthy that two QTL for mesocotyl elongation were colocalized with the QTL for mesocotyl length reported in the previous QTL reports. These QTLs can be introgressed into cultivar background using marker assisted backcrossing in an effort to enhance the level of mesocotyl elongation.

밀양23호/기호벼 재조합자식 유전집단을 대상으로 PCR 기반 DNA 마커들로 구성된 분자유전자지도를 만들고자, 주로 아가로스 젤 상에서 분석이 가능한 마커들을 위주로 STS, InDel, RTM, SSR 마커들을 선발하여 분석하였다. InDel 마커 37개, STS 마커 88개, RTM 마커 8개, SSR 마커 91개를 포함한 224개의 마커로 구성된 유전지도를 만들었는데, 총 유전거리는 1,425 cM이었으며, 마커간 평균거리는 6.7 cM이었다. 이들 DNA 마커들의 프라이머 시퀀스 정보를 바탕으로 e-PCR프로그램을 이용하여 각 마커들의 벼 유전체상에서의 물리적인 위치를 파악하고 물리지도를 작성하였다. 이 물리지도에서 마커간의 물리적 거리의 합은 356.8 Mbp이었으며, 총 유전거리에서 이를 나누어 구한 1 cM당 평균 물리적 거리는 250 kbp이었다. 5% 유의수준에서 분리비 편의(segregation distortion) 현상을 보인 마커는 전체 마커의 22.8%인 51개이었으며, 주로 3번 염색체의 중간부위, 6번 염색체의 거의 모든 영역, 7번 염색체의 상단부위, 8번 염색체의 하단부위, 12번 염색체의 상단부위에 분포하였다. 이 분자유전자지도는 자포니카형 품종과 통일형 품종 또는 인디카 품종간의 교배후대 집단에서 유용형질의 유전자 위치를 분석하고자 할 때 이용 가능한 마커들에 대한 정보를 제공할 것이다.

Cold stress at the seedling stage is a major threat to rice production. Cold tolerance is controlled by complex genetic factors. We used an F7 recombinant inbred line (RIL) population of 123 individuals derived from the cross of a cold-tolerant japonica and a cold-sensitive indica cultivars, for QTL mapping. Phenotypic evaluation of the parents and RILs in an 18/8oC (day/night) cold-stress regime showed continuous variations for cold tolerance or sensitivity. Six QTLs for seedling cold tolerance were identified on chromosomes 1, 2, 4, 10, and 11 with percent phenotypic variation (R2) ranging from 6.1% to 16.5%. Three main-effect QTLs (qSCT1, qSCT4, and qSCT11) were detected in all cold-tolerant RILs which explained high sum of phenotypic variation (SPV) ranging from 27.1% to 50.6%. Two QTLs (qSCT1 and qSCT11) on chromosomes 1 and 11 were fine mapped. The marker In1-c3 from ORF LOC_Os01g69910 of the BAC clone B1455F06 encoding calmodulin-binding transcription activator (CAMTA) and another marker, In11-d1 from ORF LOC_Os11g37720 (Duf6 gene) of the BAC clone OSJNBa0029K08, co-segregated with seedling cold tolerance. These two InDel markers amplified 241-bp and 158-bp alleles, respectively, in cold-tolerant RILs, and in the cold-tolerant donor Jinbu, which were absent in cold-sensitive parent BR29 and cold-sensitive RILs.

본 연구는 최근 콩 재배에서 심각한 병으로 대두된 콩 불마름병에 대한 저항성 유전자인 rxp 근접분자표지를 개발하고자 수행하였다. 콩 불마름병은 국내에서 전국적으로 발생하는 심각한 세균병으로 이에 관련하여 세균병 접종을 이용한 저항성 품종과 감수성 품종에 대한 연구가 많이 진행되고 있지만 정확한 유전자의 염기서열이 밝혀져 있지 않고 있다. 본 연구는 콩 불마름병에 저항성 품종 8개체와 감수성 품종 8개체를 이용하여 rxp 유전자 근접분자표지를 확인하기

The objective of this study was to map gene/QTL for photoblastism in a weedy rice (photoblastic rice: PBR) using DNA markers. Light-induced effect on germination of seeds was compared among three accessions (Oryza sativa L.), PBR, Milyang 23 and Ilpum. Results showed that PBR seeds started to show photoblastism during seed development, different from Ilpum and Milyang 23. Frequency distribution of germination in the F4 lines from crosses between Ilpum and PBR and, Milyang 23 and PBR revealed bimodal distributions suggesting that photoblastism was controlled by a few genes. Bulked segregant analysis using F4 populations derived from the above two crosses was conducted to identify gene/QTL for photoblastism. Two QTL were identified on chromosomes 1 and 12 explaining 11.2 and 12.8% of the phenotypic variance, respectively. Two QTL were further mapped between two SSR markers, RM8260 and RM246 on chromosome 1, and between RM270 and 1103 on chromosome 12. It is noteworthy that two QTL for photoblastism were colocalized with the QTL for seed dormancy reported in the previous QTL studies. The clustering of two genes for photoblastism and dormancy possibly indicates that these regions constitute rice phytochrome gene clusters related to germination. Because PBR has a low degree of dormancy, a pleiotropic effect of a single gene controlling dormancy and photoblastism can be ruled out. The linked markers will provide the foundation for positional cloning of the gene.