Cabbage head splitting can greatly affect both the quality and commercial value of cabbage (Brassica oleracea). To detect the genetic basis of head-splitting resistance, a genetic map was constructed using an F2 population derived by crossing “748” (head-splitting-resistant inbred line) and “747” (head-splitting-susceptible inbred line). The map spans 830.9cM and comprises 270 markers distributed in nine linkage groups, which correspond to the nine chromosomes of B. oleracea. The average distance between adjacent markers was 3.6cM. A total of six quantitative trait loci (QTLs) conferring resistance to head splittingwere detected in chromosome 2, 4, and 6. Two QTLs, SPL-2-1 and SPL-4-1, on chromosomes 2 and 4, respectively, were detected in the experiments over 2 years, suggesting that these two potential loci were important for governing the head-splitting resistance trait. Markers BRPGM0676 and BRMS137, which were tightly linked with head-splitting resistance, were detected in the conserved QTL SPL-2-1 region using bulked segregant analysis. Synteny analysis showed that SPL-2-1 was anchored to a 3.18Mb genomic region of the B. oleracea genome, homologous to crucifer ancestral karyotype E block in chromosome 1 of Arabidopsis thaliana. Moreover, using a field emission scanning electron microscope, significant differences were observed between the two parental lines in terms of cell structures. Line “747” had thinner cell wall, lower cell density, larger cell size, and anomalous cell wall structure compared with the resistant line “748”. The different cell structures can provide a cytological base for assessing cabbage head splitting.

Rice is a staple food crop for more than half of the world population. Severe losses of rice production was caused by various environmental conditions such as cold, heat and flooding annually. Rice is a highly sensitive to low temperature below 15-20 ℃ because of originating from tropical or subtropical climates. Especially, seedling of rice is easily damaged to low temperature and result in seedling yellowing, growth retardation, reduced tillering and yield losses at last. We used a recombinant inbreeding lines (RIL) population of 384 individuals derived from a cross between Hanareum 2, a highly cold sensitive variety and Unkwang, a cold tolerant variety for molecular mapping of QTLs related to cold tolerance. Seedling discoloration of each lines and parents caused by cold response were investigated in field condition after transplanting. And leaf samples of RIL population were collected for evaluation of chlorophyll content using 80% acetone extraction. The seedling of each lines and parents was subjected to low temperate by 5~13 ℃ during 14 days. The cold recovery score (CRS) of RILs was recorded after 4 days recovery period according to standard evaluation system (SES, IRRI). Total of eight QTLs were detected on chromosome 1, 7, 8, 10, 11 and 12 using cold tolerance traits, chlorophyll content, seedling discoloration and cold recovery score in 384 RILs. The qCRS12, which detected on chromosome 12 between two flanking markers id12002113, id12002563 (1.1 Mbp) showed 25 LOD score with 26% of phenotypic variation of cold recovery score in RILs population. The positive allele contributing to cold tolerance came from the cold tolerant parent Unkwang. The result may provide useful information for a marker-assisted breeding program to improve cold tolerant in rice.

Improving rice high-quality potential is to suffice the food demand of the rapid decreasing consumption, and is a major breeding target recently. We calculated the alkali digestion value (ADV), used to indirectly measure gelatinization temperature, to evaluate the quality of cooked rice in 2013 and 2014. The ADV score of frequency distribution was higher milled rice than brown rice. In total, nine different quantitative trait loci (QTLs) were found on chromosomes1, 3, 5, 6 and 8 in 2013 and 2014. Also, chromosome 5, 8 were detected over two years. The polymorphism using RM223, RM3530, and RM18130 markers can be used to select lines that have a good trait for breeding of high-quality rice. We conclude that selected molecular markers from this QTL analysis could be exploited in future rice quality.

In total, 120 ‘Cheonghcheong/Nagdong’ doubled haploid (CNDH) populations was developed by F1 derived from a crossing whitebacked planthopper (WBPH, Sogatella furcifera) resistance ‘Cheongcheong’ and susceptible ‘Nagdong’ lines. The main objective of this research was to determine the rice resistance optimum screening after infesting by WBPH and identify quantitative trait loci (QTLs) associated with rice resistance in order to provide consistent information for marker-assisted selection (MAS) and develop new varieties. The genetic map with average 9.6 centimorgans (cM) between markers was constructed from 120 CNDH populations using 217 SSR markers. In this study, The result of determine rice with WBPH infestation showed that the rice damage and resistance at 7, 14, and 21 days, were 100%, 76%, and 10% resistance lines of 120 CNDH population. Four QTLs were detected on four regions of the chromosomes 1 and chromosome 8, which contained qWBPH1 and qWBPH8 for resistance rice. The markers were found to be contained in identification the genetic markers RM3482, RM1196, RM3709, RM11694, RM11669, RM17699 and RM264 for marker assisted selection. These markers efficiently were shown to be very useful for MAS in breeding populations of crossing lines associated simple sequence repeat (SSR) marker with WBPH resistance in 120 CNDH populations.

Phytophthora capsici an Oomycete pathogen is a major challenge to the pepper (Capsicum spp.) production around the world. Control measures are proved ineffective, so breeding resistant cultivars are the most promising strategy against the pathogen. Resistance against P. capsici is governed by quantitative trait loci (QTL). According to previous studies on QTL detection, the QTL on pepper chromosome 5 is a major contributor to resistance. In this study, to exploit the involvement of this QTL and identify its contributing genes, the F2 population derived from a cross between ECW30R and CM334 was inoculated with a medium virulence P. capsici strain JHAI1-7 zoospores at the 6-8 leaf stage. Composite interval mapping revealed two major QTLs; QTL5-1 from 7 days post inoculation (dpi) and QTL5-2 from 16 dpi on chromosome 5. To characterize and detect interactions of the two QTLs, near isogenic lines (NIL) were constructed by crossing Tean and recombinant inbred line (RIL) derived from a cross between YCM334 and Tean. RILs were screened with P. capsici strain MY-1 and resistant lines were selected. Among the resistance RILs most closely related to Tean were selected using AFLP and SSR genotyping data. These RILs were named as YT39-2 and YT143-2. To develop more advanced NILs, two rounds of marker-assisted backcrossing were done using a high-throughput SNP genotyping system (EPI Fluidigm, USA). Among the NILs derived from YT39-2, YT39-2-64 contains only QTL5-1 whereas YT39-2-61 and YT39-2-69 were identified to have both QTLs. On the other hand, YT143-2-55-7 with the highest Tean genetic background contains QTL5-1 only. In the next step, the 3 different NILs having QTL5-1, QTL5-2 individually and both QTLs will be identified. Furthermore, phenotyping and fine mapping will be done for the analysis of individual and interaction effects of QTLs.

Foxglove aphid, Aulacorthum solani (Kaltenbach), is a Hemipteran insect that infected a wide variety of plants worldwide and caused serious yield losses in crops. The objective of this study was to identify the putative QTL for foxglove aphid resistance in wild soybean, PI 366121, (Glycine soja Sieb. and Zucc.). One hundred and forty one F2-derived F8 recombinant inbred lines developed from a cross of susceptible Williams 82 and resistant PI 366121, were used. The phenotyping of antibiosis and antixenosis was done through choice and no-choice assays with total plant damage (TPD) and primary infestation leaf damage (PLD); a genome-wide molecular linkage map was constructed with 504 single nucleotide polymorphism markers utilizing a GoldenGate assay. Using inclusive composite interval mapping analysis for foxglove aphid resistance, one major candidate QTL on chromosome 7 and 3 minor QTL regions on chromosome 3, 6 and 18 were identified. The major QTL on chromosome 7 showed both antixenosis and antibiosis resistance responses. However, the minor QTLs showed only antixenosis resistance response. The major QTL mapped to a different chromosome than the previously identified foxglove aphid resistance QTL, Raso1, from the cultivar Adams. Also, the responses to the Korea biotype foxglove aphid were different for Raso1, and the gene from PI 366121 against the Korea biotype foxglove aphid were different. Thus the foxglove aphid resistance gene from PI 366121 was determined to be an independent gene to Raso1 and designated to Raso2. This result could be useful in breeding for new foxglove aphid resistant soybean cultivars.

Drought is a one of the most serious abiotic stresses limiting rice production. However, little progress has been made in the genetic analysis of drought tolerance, because it is a complex trait controlled by a number of genes and affected by various environmental factors. The most efficient method for drought tolerance breeding is using drought tolerance genetic resources. We used a doubled-haploid (DH) population consist of 101 lines derived from a cross the drought tolerant cultivar ‘Samgang’ and the drought sensitive cultivar ‘Nagdong’ for QTL analysis. Drought stress was treated by withholding water for 6 weeks, and then rewatered for 7 days. After rewatering visual phenotype was observed according to the standard evaluation system for rice, IRRI. Drought sensitive parent ‘Nagdong’ was almost died, while tolerant parent ‘Samgang’ showed slightly leaf tip dring phenotype. The qdr11 detected on chromosome 11 with flanking markers RM26755-RM287 and accounted for 19% phenotype variation with a LOD score of 3.7.

The next-generation sequencing (NGS) technology is being used for more effective genetic mapping and genome analysis. In this study, we performed whole-genome sequencing on the genomic DNA of Milyang23 and Gihobyeo using NGS and developed new cleaved amplified polymorphic sequence (CAPS) markers based on the single nucleotide polymorphisms (SNPs) in coding sequence between these varieties. Approximately, sequences of 60x coverage of the Nipponbare reference genome on average were obtained following Illumina sequencing. Totally, 1,726,798 SNPs between Milyang23 and Gihobyeo were detected. Among them, 149 SNP were selected for CAPS markers and located on genetic map with previously reported 219 PCR-based DNA markers. This map was applied to the detection of quantitative trait loci (QTLs) for stem internode diameters, culm length and panicle length in rice with MGRIL population. Newly 6 QTLs were detected for culm length (CL) and stem diameter (ID) traits including the first internode diameter (I1D), third internode diameter (I3D), and fourth internode diameter (I4D). Among those QTLs, qI1D5 and qCL5 had relatively higher LOD score and explained 8.99% and 4.24% of total variation. This study showed that the NGS allowed the rapid discovery of a large number of SNPs for CAPS marker. Only very small portion of SNPs through re-sequencing were used in this study. Furthermore, the results of QTL analysis described above shows relevance of molecular markers in mapping genes for useful traits.

New QTLs were identified for high grain yield with long panicle in rice. A total of 137 F15 recombinant inbred lines (RILs) derived from a cross between Dasanbyeo (Tongil) and TR22183 (japonica), together with the parents were evaluated for 16 agronomic traits at IRRI in dry and wet seasons under different phosphorus (P) and irrigation conditions. A linkage map was constructed using 236 polymorphic markers in 384-plex Bead Xpress indica-japonica single nucleotide polymorphism (SNP) platform. P and water effects were significant in both wet and dry seasons. Both parents and RILs showed varying degree of sensitivities to scarcities in water and phosphorus in terms of panicle length. Collocating with 20 yield-related QTLs, the panicle QTLs on chromosomes 1 (pl01) ,2 (pl02), 9 (pl09), and 11 (pl11) under low P and rainfed conditions were identified. RILs with TR22183 allele at pl11 showed longer panicle length under low P input rainfed condition in dry and wet seasons. The whole-genome sequences of the two varieties are being compared to design the molecular markers for fine-mapping and candidate gene identification. Based on Nipponbare MSU 7.0 annotation, a total of 1464 genes with predicted function were identified within the four QTL regions. Candidate genes identified in other studies for QTLs under low P and water conditions, such as calmodulin and dehydrin genes, were targeted for designing molecular markers for fine-mapping and expression analysis. Pyramiding the panicle length QTLs correlating with yield QTLs will provide an opportunity of improving yield traits.

Hybrid sterility is one of the major barrier to the application of wide crosses in plant breeding and is commonly encountered in crosses between indica and japonica rice varieties. Ten mapping populations comprised of two reciprocal F2 and eight BC1F1 populations generated from the cross between Ilpumbyeo (japonica) and Dasanbyeo (indica) were used to identify QTLs and to interpret the gametophytic factors involved in hybrid fertility or sterility between two subspecies. Frame maps were constructed using a total of 107 and 144 STS markers covering 12 rice chromosomes in two reciprocal F2 and eight BC1F1 populations, respectively. A total of 15 main-effect QTLs and 17 significant digenic- epistatic interactions controlling spikelet fertility (SF) were resolved in the the entire genome map of F2 BC1F1 populations . Among detected QTLs responsible for hybrid ferility, four QTLs, qSF5.1 and and qS F5.2 on chromosome 5, qSF6.2 on chromosome 6, and qSF12.2 on chromosome 12 were identified as major QTLs since they were located at corresponding position in at least three mapping populations. Loci qSF5.1, qSF6.1 and qSF6.2 were responsible for both female and male sterility, whereas qSF3.1, qSF7 and qSF 12.2 affected the spikelet fertility only through embryosac factors, and qSF9.1 did through pollen factors. Five new QTLs identified in this study will be helpful for understanding the hybrid sterility and for breeding programs via inter-subspecific hybridization.

Hybrid sterility is one of the major barrier to the application of wide crosses in plant breeding and is commonly encountered in crosses between indica and japonica rice varieties. Ten mapping populations comprised of two reciprocal F2 and eight BC1F1 populations generated from the cross between Ilpumbyeo (japonica) and Dasanbyeo (indica) were used to identify QTLs and to interpret the gametophytic factors involved in hybrid fertility or sterility between two subspecies. Frame maps were constructed using a total of 107 and 144 STS markers covering 12 rice chromosomes in two reciprocal F2 and eight BC1F1 populations, respectively. A total of 15 main-effect QTLs and 17 significant digenic- epistatic interactions controlling spikelet fertility (SF) were resolved in the the entire genome map of F2 BC1F1 populations . Among detected QTLs responsible for hybrid ferility, four QTLs, qSF5.1 and and qS F5.2 on chromosome 5, qSF6.2 on chromosome 6, and qSF12.2 on chromosome 12 were identified as major QTLs since they were located at corresponding position in at least three mapping populations. Loci qSF5.1, qSF6.1 and qSF6.2 were responsible for both female and male sterility, whereas qSF3.1, qSF7 and qSF 12.2 affected the spikelet fertility only through embryosac factors, and qSF9.1 did through pollen factors. Five new QTLs identified in this study will be helpful for understanding the hybrid sterility and for breeding programs via inter-subspecific hybridization.

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.

For QTL analysis of agronomic traits based on cultivation of low and high altitude locations, BC1 F5 181 lines were developed from a cross of Tongil type Gayabyeo and japonica Chhomrong originated from Nepal. Plant materials were grown in both of low altitude area of Milyang, Korea and high altitude area of Khumaltar, Nepal. In QTLs analysis, a total of 42 QTLs were detected in days to flowering, culm length, panicle length, number of panicles/hill, panicle exertion, and spikelet ripening ratio. Although many of the QTLs were coincided between the two locations of Korea and Nepal, several QTLs were revealed as location specific in high altitude area of Khumaltar. Especially, the regions harboring marker RM489-RM14281 on chromo- some 3, RM5642-RM19049 on chromosome 5, and RM2854-RM6696 on chromosome 12 where QTLs were clustered and coincided between the two locations are considered as positive target regions for environmental independent traits. Furthermore, high rate of location specific QTLs such as panicle exertion and spikelet ripening ratio could be considered carefully for understanding the mechanism of cold tolerance based on cultivation of different altitude location.

본 연구에서는 자포니카형인 '낙동'과 통일형인 '삼강' 조합의 DH 집단을 이용하여 식미를 결정하는 특성 중 하나인 호응집성과 미립의 이화학적 특성인 천립중, 장폭비, 아밀로즈 함량, 단백질 함량, 지질 함량 및 전분 함량 간 상관관계를 검정하였다. 또한 호응집성의 QTL을 분석하고, 각 QTL에 속하는 DNA marker와 DH 집단의 호응집성 및 품종별 호응집성 간 관계를 분석하였다. '삼강/낙동' DH 집단의 호응집성 범위는 35~94 mm로 비교

벼멸구 저항성 유전자의 mapping, 벼멸구 저항성 관련 QTL 분석, 주요 농업형질과 벼멸구 저항성과의 관계 분석 등에 관한 연구를 수행 하여 얻은 결과는 다음과 같다. 벼멸구 저항성을 가진 통일형 벼인 '삼강'과 자포니카형 벼인 '낙동'을 교배하여 양성된 F_1의 약을 배양하여 육성된 120 DH 계통을 유전자 지도 작성을 위한 mapping 재료로 이용 하였다. Maker 검정에서 양친에 다양성을 나타낸 SSR 73, STS 89개 등 총 162