본 연구는 국내 잡초벼인 완도앵미6의 식미관련 유용인자를 자포니카벼 품종에 도입하여 식미가 개선된 새로운 품종을 개발하기 위한 기초 육종연구로 수행되었다. 식미개선을 위하여 국내 자포니카 벼 품종인 화영과 윤기치가 우수한 국내 잡초 벼인 완도앵미6를 교배하여 재조합 자식계통을 육성하였으며 이 조합으로부터 고품질 품종 개발에 활용 가능한 우량계통을 육종에 이용하고자 수행한 결과는 다음과 같다. 1. 화영과 완도앵미6 조합의 교배립을 생산하여 SSD법으로 8세대까지 계통전개 하였으며 초형 등을 고려하여 최종 224계 통의 RIL을 육성하였다. 2. 육성된 RIL집단의 주요 농업특성 특성을 3년(2016-2018) 간 평가하여 연차간 변이를 확인하였으며, 육성된 집단으로부터 작물학적 특성과 식미관련 특성이 우수한 10계통을 선발하였다. 3. 선발된 계통에 대한 아밀로스 함량, 단백질 함량, 알칼리 붕괴도 등의 이화학적 특성을 분석하였는데, 특히 선발된 계통 모두가 수여친인 완도앵미6의 수준에서 윤기치가 개선된 것을 확인하였다. 4. 식미와 관련이 높은 것으로 알려진 밥의 질감과 관련하여 관능평가와 기계적 물성 측정값에 대한 비교에서 두 방법 간에 상관이 확인되지 않아 이에 대한 보완 연구가 필요할 것으로 사료된다.

Genetically modified (GM) crops have never been cultivated commercially in Korea, it is necessary for a thorough assessment of the risks associated with their environmental release. We determined the frequency of pollen mediated gene flow from disease resistant GM rice (OsCK1) to non-GM rice (Nagdongbyeo) and weedy rice (R55). A total of 449,711 or 164,604 seeds were collected from non-GM and weedy rice, respectively which were planted around OsCK1. Resistance of the hybrids was determined by repeated spraying of herbicide and DNA analysis using specific primer to confirm hybrids. Though non-GM rice and weedy rice have similar flowering time, the hybrids were found only in non-GM rice and out-crossing ranged from 0.018% at 0.3 m to 0.013% at 0.6 m. All of hybrids were located within 0.6 m distance from the GM rice plot in southerly direction. The meteorological factors including temperature and relative humidity during flowering time were found to be the most important factors for determining rice out-crossing. It should be considered many factors like the local weather condition and flowering time to set up the safety management policy to prevent pollen mediated gene flow between GM and conventional crop.

For understanding the genetic diversity and genetic relationship between cultivated and weedy types, we evaluated genetic variation of 80 accessions of rice (O. Sativa). This included 42 cultivated accessions and 38 weedy accessions with the help of AFLP and CACTA-TD. A total of 542 loci were analyzed (255 for AFLP and 287 for CACTA-TD) of which AFLP markers exhibited 75% of polymorphism and transposon based CACTA-TD markers exhibited 93% of polymorphism. The average genetic diversity value for all 80 accessions, using AFLP markers was 0.226 (Cultivated – 0.210; Weedy 0.241) and based on CACTA-TD markers was 0.281 (Cultivated – 0.294; Weedy 0.269). A UPGMA phylogenetic tree revealed three major groups for both the marker system. The average polymorphic content value obtained with AFLP and CACTA-TD markers were 0.21 and 0.232, Effective multiplex ratio (AFLP – 47.50; CACTA-TD – 66.75), Marker Index (AFLP – 9.94; CACTA-TD – 21.13) and Resolving power (AFLP – 19.53; CACTA-TD – 34.62) indicated that the CACTA-TD markers were relatively efficient than AFLP markers.

Rice blast caused by the fungal pathogen, Magnaporthe oryzae, is a serious disease affecting yield loss and decreasing its quality in rice production. Rice breeders in Korea have developed many japonica varieties showing resistance to blast. However, the blast resistance in most japonica varieties has broken down within a few years after they were released to farmers because of the spread of new virulent races of M. oryzae. There is the most effectiveness to look for novel resistant gene(s) that can express the resistance to broad-spectrum races in diverse environmental conditions. We identified a major QTL, qLB4.1 linked tightly to RM6352 and RM3643 in 52.6 cM region on chromosome 4 related to the resistance for isolate inoculation and nursery test, and neck blast from a Korean weedy rice, Geumleungaengmi33. This QTL explained 26.1∼28.6% and 45.3∼53.1% of total phenotypic variation by the allele of GL33 for isolate inoculation and nursery test, respectively. A line SR30058(52)-1-1 (Suweon545) that containing the QTL qLB4.1 was developed from Ilpum*4/GL33 by marker-assisted backcross method. This line showed resistant reactions to blast nursery test across regions and years, and resistance to neck blast at the hot-spot field in Jecheon. Suweon545 showed also durable resistance of lower 10% of diseased leaf areas (DLAs) in sequential planting method. This line screened by graphical mapping using 136 SSR markers that evenly distributed on 12 chomosomes. Suweon545 contained GL33 alleles of donor parent in a total of 12 loci (8.8%) including QTL region on chromosome 4. In future, Suweon545 would be useful to develop the broad-spectrum resistance variety in japonica rice breeding program.

Genetically modified (GM) crops have never been cultivated commercially in Korea, it is necessary for a thorough assessment of the risks associated with their environmental release. We quantified the amount determined the frequency of pollen mediated gene flow from disease resistant GM rice to weedy rice (R55). A total of 164,604 seeds were collected from weedy rice, which were planted around GM rice. Resistance of the hybrids was determined by repeated spraying of herbicide and DNA analysis using specific primer to confirm hybrids. Though weedy rice has similar flowering time, the hybrids were found only in non-GM rice and out-crossing ranged from 0.018% at 0.3 m to 0.013% at 0.6 m. All of hybrids were located within 0.6 m distance from the GM rice plot in southerly direction. The meteorological factors including temperature and relative humidity during flowering time were found to be the most important factors for determining rice out-crossing. It should be considered many factors like the local weather condition and flowering time to set up the safety management policy to prevent pollen mediated gene flow between GM and conventional crop.

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.

본 연구는 국내 수집 잡초성벼에 존재하는 잎도열병 저항성 관련 유전자를 탐색하고, 이 저항성유전자와 연관된 분자마커를 탐색하는 것이다. 도열병에 감수성인 자포니카 품종인 낙동벼와 도열병에 강한 잡초성벼인 강화앵미11을 교잡하여 120개 RILs를 육성하여, 도열병 균주반응과 잎도열병 밭못자리검정을 통한 저항성 유전자 탐색에 이용하였다. 1. 총 45개 도열병 균주를 이용하여 양친들을 검정한 결과, 잡초성벼 강화앵미11은 25개 균주에 대하여 저항성 반응

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.

QTL analysis for cold tolerance-related traits was conducted using 75 introgression lines (IL) developed from a cross between a japonica weedy rice and Tongil-type rice. A molecular linkage map consisting of 136 SSR markers was constructed to identify QTLs associated with cold tolerance. 75 ILs and the parents were evaluated for three traits associated with cold tolerance: seedling height and SAPD values at the seedling stage. The plants were grown for 15 days in the low temperature condition (13/20℃ day/night) and the control condition (25/20℃ day/night) in the growth chamber. A total of six QTL were identified for two traits and phenotypic variance explained by each QTL ranged from 4.3% to 35.7%. Among two QTL for seedling height, one QTL, sh1 for seedling height was detected at both conditions. The other QTL on chromosome 6 was detected in the low temperature condition. Four QTL were identified for SPAD value and two were detected on chromosomes 2 and 5. At these loci, Milyang 23 alleles increased the SPAD value. The other two QTL on chromosomes 1 and 4 were detected at the low temperature plot. At these loci, Hapcheonaengmi 3 alleles increased the SPAD values. These results indicate that Hapcheonaengmi 3 alleles might increase tolerance to low temperature in the Milyang 23 background because SPAD value is positively correlated with chlorophyll content and N content in rice. The markers linked to low temperature tolerance at the seedling stage would be useful in selecting for lines with enhanced cold tolerance in a breeding program.

Direct-seeding method on dry paddy soil could make rice farming large-scale cultivation and cost-saving, but it has still some problems on poor seedling establishment caused by low temperature and varying sowing depth. This research was carried out to identify weedy rice genetic resources that may help to poor seedling establishment in direct-seeded rice on dry paddy soil in temperate region. The genetic resources screened in this study were 128 accessions that consist of 92 japonica weedy rices, 24 indica weedy rices, and 12 Korean bred cultivars.The weedy rices on average have very superior abilities to emerge form depth than cultivated rice. The germplasm showed that the coleoptile or/and mesocotyl lengths were positively correlated with emergence rate to a high degree. Among the germplasm, WD-3, a japonica weedy rice, evidenced the highest level of emergence with the longest coleoptile and mesocotyl elongation. The emergence ability of WD-3 depending on the burial depth under low temperature condition was confirmed in both the phytotron and the field conditions. WD-3 showed 100% of emergence rate until a burial deptho f 7 cm in the dry soil in the phytotron, and 76.2 % of very high emergence rate in the total layer of paddy field where the seeds were sown from the surface to 10 cm depth. In the emerged plants in the field, the mesocotyl elongation increased with increasing burial depth in a logarithmic fashion, and the coleoptile extension increased exponentially. The total elongation lengths of the mesocotyl and coleoptile were similar with a plant burial depth, which indicated that they could induce the safe emergence of the main leaf of the seedling from the soil to thesurface. Conclusively, the elongation habit of mesocotyl and coleoptile of WD-3 could be one of the important characteristics to develop direct-seeding cultivars.

This experiment was carried out to investigate the relationship between grain shapes and ecotypes in Korean native weedy rice. The 111 lines of Korean weedy rice were classified into japonica (91 lines) and indica (20 lines) by RAPD analysis, which was reported in 2005 (Chung and Ahn). The characteristics of grain shape such as grain length, width, thickness, 1,000 grain weight, the ratio of length to width (L/W), the ratio of length to thickness (L/T), and the ratio of width to thickness (W/T) were measured in each ecotype, and their statistical distributions were compared by t test. The mentioned 7 characteristics were significantly different between japonica and indica weedy rice groups, but these could not classify weedy rice accessions into two groups without exceptions according to the classification by RAPD analysis. Out of variables concerning grain shape, the L/W was the highest distinctive to separate ecotypes. A critical point of L/W to divide ecotypes was calculated from the mid point between upper critical limit of japonica and lower critical limit of indica in confidence interval at α=0.05. At critical point of L/W = 2.138, decision error was 2.2% in japonica group, and 5.0% in indica group. Conclusively, the classification of ecotypes by L/W of grain made almost (under 5% error) same result with that by RAPD markers in Korean native weedy rice.

This study was carried out to identify the quantitative trait loci (QTLs) for traits related to cold tolerance using an introgression lines (ILs) derived from a cross between a japonica weedy rice and a Tongil-type rice. Among the 80 RILs, one line (CR1835) showing tolerance for cold tolerance related to traits such as panicle exsertion and discoloration in the cold water plot was selected and backcrossed to the recurrent parent, Milyang 23. This line possessed Hapcheonaengmi 3 segments on chromosomes 1, 5 and 11. By two backcrosses to Milyang 23 and selfing, a total of 88 BC3F5 progenies were developed. The 88 ILs were evaluated for traits related to agricultural performance in cold water and in control plots. Cold tolerance was measured as difference of the culm length, spikelet fertility between two plots and panicle exsertion in cold water plot. The 88 ILs showed decreased culm length and increased anthocyan content in cold water plot than in the control water plot.

This study was conducted to investigate the crossability, seed dormancy and overwintering ability of rice plant in GM (glufosinate ammonium-resistant lines. Iksan 483 and Milyang 204) and non-GM (their parents) or red rice (Andongaengmi). Seed-setting rate was not significantly different between GM and non-GM rice varieties. Iksan 483 and Milyang 204 showed the similar level of seed germination rate from 30 to 50 days after heading as compared to non-GM rice varieties. After overwintering in paddy field, seed germination rate of GM and non-GM rice varieties ranged from 14.3 % to 57.6 % in dry soil condition, but there was no germination in wet-soil except red rice. The result in wet-soil condition may help to set up a strategy for reducing the risk of gene flow of transgene via dispersal of seeds of GM plants. The crossability, seed dormancy and seed overwintering of Iksan 483 and Milyang 204, herbicide resistant GM rice varieties, were not significantly different compared to non-GM rice varieties. The results might be helpful to reduce the risk of transgene dispersal from GM crop via seeds and pollens.