‘화원5호’는 ‘일품벼’의 유전적 배경에 ‘모로베레칸’의 도열병 저항성 유전자가 이입된 근동질 계통을 육성하기 위해 ‘일품벼’와 ‘모로베레칸’을 교배하고, 계속적인 여교배와 MAS를 병행 실시하여 육성한 계통이다. ‘화원5호’는 ‘일품벼’의 유전적 배경에 염색체 1번, 4번 및 6번에 ‘모로베레칸’의 염색체단편이 이입된 것으로 나타났으며, 염색체 4번에 위치한 ‘모로베레칸’의 단편이 도열병 저항성을 증진시켰다. ‘화원5호’의 출수기는 보통기 재배에서 8월 19일로 ‘일품벼’와 동일한 중생종 품종이며, 천립중은 23.8 g으로 ‘일품벼’와 유사한 수준이었다. 완전미율은 ‘일품벼’에 비해 약간 낮았고, 아밀로스 함량은 ‘일품벼’보다 높았으나 통계적인 차이는 없었다. ‘화원5호’의 정조수량은 2005년부터 2006년간 실시한 생산력검정 시험에서 평균 6.53 MT/ha로 ‘일품벼’ 대비 102% 수준이었다. 4개 지역에서 2개년간의 밭못자리 검정 및 연계재배법을 이용한 도열병 검정 결과, ‘화원5호’는 ‘일품벼’에 비해 도열병 저항성이 증진된 것으로 나타났다. 생산력검정 시험 결과 조사된 형질 중 도열병저항성을 제외한 기타 형질에서는 ‘일품벼’와 유사한 근동질계통으로, 품종보호 출원 조건에 부합하여 ‘화원5호’로 명명하고 품종보호원을 출원하였다.

국내 밀 품종 조경, 금강 그리고 중국 밀 품종인 Chinese spring의 genomic DNA를 주형으로 LMW-GS 특이 프라이머세트를 이용하여 3개의 새로운 LMW-GS i 타입 유전자를분리하였고 이들의 분리된 유전자는 각 각 조경 II-2, CSIII-5 그리고 금강 6-12로 명명하였다. 이들의 유추 아미노산을 분석한 결과 20개의 시그널 펩타이드, 이소루신으로 시작하는 N-말단 부분 그리고 글루타민이 많은 반복도메인 그리고 C-말단 부분으로 구성되어 있으며 조경 II-2와 CS III-5는 전형적인 LMW-GS i-type 유전자처럼 C-말단에 8개의 시스테인 잔기가 있었다. 금강 6-12는 특이하게도 하나 더 많은 9개의 시스테인 잔기가 존재하였는데 이 여분의 시스테인 잔기는7번째 시스테인 잔기의 11잔기 앞에 존재하며 TAT(타이로신)이 TGT(시스테인)로 바뀐 결과이다. LMW-i 타입 글루테닌 유전자들 간의 SNP와 InDel을 확인하기 위해서 본 연구에서 클로닝 된 조경 II-2, CS III-5 그리고 이전에 본 그룹에서 확인된 조경 HQ619933와 기존 문헌에 나와 있는 6배 체 밀 유래의 10개의 LMW-GS i 타입 유전자들과 다중염기서열 분석을 실시하였고, 이들 사이에서 15개의 SNP와 1개의 insertion이 확인되었다. 밀 품종 조경의 Glu-A3 단백질을 동정하기 위해 글루테닌을 추출 이차원전기영동을 하고 Glu-A3c 위치의 스팟을 절취하여 in-gel digestion한 후 LC-ESI MS/MS 분석을 수행한 결과 조경의 i 타입 LMW-GS 유전자 좌는 Glu-A3c로 확인되었다. LMW-i 타입 글루테닌 유전자들의 연관 관계를 분석하기 위해 본 연구 그룹에서 클로닝 한 조경 II-2, CS III-5, 금강 6-12 그리고 조경 HQ6199333와 Genebank DB의 35개의 LMW-i 타입 글루테닌 유전자의 유추 아미노산 서열을 이용하여 Phylogenic tree를 완성하였다. 이들 39개의 계통도 분석 결과 이배체 밀과 4배체 밀의 LMi 타입 글루테닌이 육배체 밀의 LMW-i 타입 글루테닌과 크게 나눠지는 것을 확인하였으며, 육배체 밀의 LMW-i 타입 글루테닌들은 Glu-A3a부터 GluA-3g까지 7개 subgroup으로 나눠지는 것을 확인하였다. 금강 6-12는 GluA-3a와 GluA-3c 사이에 존재하였고 조경 II-2와 CS III-5는 GluA-3d와 일본 연질 밀인 농림 61의 AB062878과 같은 subgroup에 존재하였고 조경 HQ6199333은 Glu-A3c subgroup에 위치하였다. LMW-i 타입 글루테닌 유전자들의 유추 아미노산 다중서열분석결과 반복 도메인은 length polymorphism은 179～149개 정도의 long 타입과 91, 51, 10, 2개의 short 타입으로 나눠지고 이것은 long 타입과 short 타입 LMW-i 타입 글루테닌 유전자를 구분 할 수 있는 마커의 근거가 된다.

Spikelets per panicle (SPP) is one of the most important traits associated with rice yield. In this study, IL28, a near isogenic line (NIL) developed by introgressing chromosomal segments from ‘Moroberekan’ into ‘Ilpumbyeo’ showed significantly higher number of spikelets per panicle than the recurrent parent, ‘Ilpumbyeo’. Quantitative trait locus (QTL) analysis in 243 F2 plants derived from a cross between IL28 and Ilpumbyeo indicated that a QTL for spikelets per panicle, qSPP6 was located in the interval RM3430 - RM20580. The Moroberekan allele increased SPP. The fact that QTLs for panicle length and the number of secondary branches were mapped in the same interval as qSPP6 appears to indicate that this locus was associated with panicle structure. To map the QTL more precisely, substitution mapping of qSPP6 using F3 lines was conducted. Substitution mapping with 41 F3 lines further narrowed the interval containing not only qSPP6 for spikelets per panicle but also qNDW6 for node width to about 680-kb between markers RM20521 and RM20572 based on Nipponbare genome sequence. The locus, qSPP6 is of particular interest because of its independence from undesirable height and flowering time. SSR markers tightly linked to the qSPP6 will facilitate cloning of the gene underlying this QTL as well as marker assisted selection for variation in SPP in the breeding program.

The objective of this study were to identify QTLs for agronomic traits using a set of introgression lines carrying wild rice (Oryza rufipogon) segment in cultivated rice (ssp. japonica cv. Hwaseongbyeo). Ninety-six ILs were evaluated for seven agronomic traits, amylose and protein contents. The proportion of the recurrent genome in ILs ranged from 87.8 to 100%, with an average of 96.7%. The mean number of homozygous and heterozygous donor segments were 2 (ranging 0-7) and 1.7 (ranging 0-6), respectively, and the majority of these segments had size less than 10 cM. A total of 22 quantitative trait loci were identified for 9 traits and each QTL explained 7.2% to 56.6% of the phenotypic variance. Some QTLs were clustered in a few chromosomal regions. A first cluster was located near RM527 on chromosome 6 with QTLs for culm length, panicle length, days to heading, 1000-grain weight and protein content. Three ILs with high spikelets per panicle compared to the recurrent parent were selected to detect and fine map the wild segments responsible for this variation. The results will be discussed.

Spikelets per panicle is one of the most important trait associated with rice yield component. In this study, IL28, near isogenic line (NIL) developed by introgressing chromosomal segments from Moroberekan into Ilpumbyeo, showed significantly higher number of spikelets per panicle than the recurrent parent Ilpumbyeo. Quantitative trait locus (QTL) analysis in 243 F2 plants derived from a cross between IL28 and Ilpumbyeo, indicated that a QTL for spikelets per panicle, qspp6, located in the interval RM3430 – RM20580. The fact that QTLs for panicle length and secondary branch number were mapped in the same interval as that for qspp6 indicated that this locus was associated with panicle structure. To map the QTL more precisely, substitution mapping of qspp6 using F4 lines was conducted. As a result, substitution mapping with ten F4 lines further narrowed the interval containing qspp6 to about 429kb between marker RM20521 and RM20562 based on the japonica genome sequence. The locus, qspp6 is of particular interest because of its independence from undesirable height and flowering time. SSR markers tightly linked to the qspp6 will facilitate cloning of the gene underlying this QTL as well as marker assisted selection for variation in SPP in an applied breeding program.

The objective of this study was to determine the genetic diversities of major rice blast resistance genes among 84 accessions of aromatic rice germplasm. Eighty four accessions were characterized by a dominant 11 set of PCR-based SNP and CAPS marker, which showed the broad spectrum resistance and closest linkage to seven major rice blast resistance (R) genes, Pia, Pib, Pii, Pi5 (Pi3), Pita (Pita-2), and Pi9 (t). The allele specific PCR markers assay genotype of SCAR and STS markers was applied to estimate the presence or absence of PCR amplicons detected with a pair of PCR markers. One indica accession, Basmati (IT211194), showed the positive amplicons of five major rice blast resistance genes, Pia, Pi5 (Pi3), Pib, Pi-ta (Pi-ta2), and Pik-5 (Pish). Among 48 accessions of the PCR amplicons detected with yca72 marker, only five accessions were identified to Pia gene on chromosome 11. The Pib gene was estimated with the NSb marker and was detected in 65 of 84 accessions. This study showed that nine of 84 accessions contained the Pii gene and owned Pi5 (Pi3) in 42 of 84 accessions by JJ817 and JJ113-T markers, which is coclosest with Pii on chromosome 9. Only six accessions were detected two alleles of the Pita or Pita-2 genes. Three of accessions were identified as the Pi9 (t) gene locus.

Brown planthopper (BPH) is a serious insect pest of rice crop throughout rice growing countries, and yield loss due to its infection can be up to 60%. This study aimed to evaluate efficiency of molecular markers for screening BPH resistance accessions among 86 aromatic rice germplasm Eighty-six accessions of aromatic rice germplasm included two accessions of Tongil type (bred in Korea), 28 accessions of japonica type and 56 accessions of indica type. We applied eight STS markers (pBPH9, pBPH19, pBPH20, pBPH21, AJ09-b, RG457L, RG457B, and 7312.T4A) which were linked to four of BPH resistance genes, Bph1, Bph13(t), Bph10, and Bph18(t) respectively. One japonica type accession, 415XIr352, and six indica type accessions possessed one or four positive bands when tested with four STS markers linked to Bph1 gene. One indica type aromatic rice, Basmati9-93, showed the target bands linked to the Bph10 gene. The other accessions did not show same fragments as the respective resistant lines. Bph13(t) is the most widely introduced resistance gene and only one accession showed positive bands implying that this accession might harbor Bph10 and Bph18(t) genes. Three aromatic accessions, Domsiah, Khao Dawk Mali 105 and 415XIr352 showed gene pyramiding of Bph1 and Bph13(t). Two indica aromatic rice, Ds 20 and Basmati 9-93, possessed at least two BPH resistance genes, Bph1, Bph18(t) and Bph13(t), Bph18(t), respectively. These results indicates that aromatic rice germplasm have narrow diversities of BPR resistance genes.

In the previous study (Yuan et al. 2009), a quantitative trait locus (QTL) for grain weight was detected on the short arm of chromosome 5 using an advanced backcross lines (BC3F3) between Hwayeongbye (Oryza sativa) and W1944(Oryza rufipogon Griff.) .For detection of gw5 locus, a line CR6 (BC3F4) was selected and crossed to Hwayeongbyeo produce S1F2 and S1F3 population. And a plant from S1F3 population, carried W1944 homozygous segment for target region at gw5 was crossed to Hwayeong to produce S2F2 population. All these population including some S1F3 lines were grown in the field in 2007, 2008 and 2009, respectively (fig1). Frequency distribution of grain weight followed the Mendelian ratios(3:1) for single locus segregation (Χ2=1.22, 0.76, 1.34 in 2007, 2008 and 2009 respectively).In Hwayeongbye genetic background, the W1944 allele at the gw5 locusde creased grain weight, QTL analysis showed that gw5 co-segregated with RM18003 and RM194 (R2=62.7, 69.5 and 37.1% in 2007, 2008 and 2009 respectively). Addition, five QTLs plant height, culm length, secondary branch, spikelet number perplant and rationing ability were detected in the region around gw5, in 2008 and 2009. Substitution mapping with 32F3 lines, gw5 QTL was flanked by two SSRmarkers, RM18003 and RM194, in a300kb to 1.7Mb physical distance region,. QTL analysis indicated that 5 others QTLs plant height, culm length, secondary branch, spikelet number per plant and rationing ability were tightly linked.

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.

β-carotene producing transformants were produced in the background of "Nagdong", a japonica rice cultivar. Introgression of the caroteniod locus into the elite cultivar "Ilpum". Was started to initiate a backcrossing program, we surveyed 220 SSR markers and found that 38% of them were polymorphic between the “Ilpum” as the recurrent parent and "Nagdong" transfomed as a recipient parent. First, backcross progenies have been produced and genotyped by the transgene specific PCR-based marker. Blast search indicated that the transgene PAC4-2 was located between SSR markers, RM5631 and RM5916. We produced 240 BC3F2 plants derived from thirteen BC3F1 plants containing the caroteniod gene. To develop near isogenic line, additional experiments including target and background selection are being performed using SSR markers. Traits of agronomic importance such as heading date, panicle number and culm length will also be evaluated. The results will be discussed.

We conducted a QTL analysis of agronomic traits using 117 BC3F5 and BC3F6 lines developed from a cross between Ilpumbyeo and Moroberekan. Genotypes of 117 BC3F5 lines were determined using 134 simple sequence repeat (SSR) markers. A total of 832 Moroberekan chromosome segments with 410 homozygous and 422 heterozygous, respectively, were detected, and the genetic distance of introgression segments ranged from 0.5 cm to 112.1 cm. A linkage map constructed using 134 SSR markers was employed to characterize quantitative trait loci (QTL). The 117 BC3F5 and BC3F6 lines were evaluated for seven agronomic traits at two locations in 2006 and 2007 and at one location in 2007. A total of 26 QTLs were identified for seven traits including days to heading, and the phenotypic variance explained by each QTL ranged from 9.2% to 24.2%. Moroberekan alleles contributed positive effects in the Ilpumbyeo background at eleven QTL loci including panicle length and spikelets per panicle. Five QTLs, two for days to heading and one each for culm length, panicle length and spikelets per panicle were consistently detected in every occasions indicating that these QTLs are stable. Among them, two QTLs, spp6 for spikelets per panicle and pl6 for paniclel length were localized in the similar region. Increase in spikelets per panicle at this locus might be due to the increase in panicle length, because both traits were associated with increase in spikelets per panicle and panicle length due to the presence of the Moroberekan allele. These Moroberekan QTLs might be useful in breeding programs to develop high-yielding cultivars.

The volatile and semi-volatile compounds of 5 accessions of domestic and 25 accessions of foreign aroma rice were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography-mass spectrum (GC-MS). A total of 158 volatile and semi-volatile compounds were identified from 30 accessions of aroma rice germplasm, including 32 alcohols, 25 acids, 25 ketones, 21 hydrocarbon, 18 esters, 16 aldehydes, 4 ethers, 5 amines, 2 phenols, 2 bases, and 8 miscellaneous compounds. By UPGMA/Neighbor-join tree analysis, the thirty aroma rice germplasms could be classified into five groups according to the major odor or aroma compounds. Group Ⅰ included Indica type of 'Basmati' varieties. GroupⅡ included Japonica type foreign aroma rice except WAR 16 (domestic aroma rice). GroupⅢ and GroupⅤ included Indica type of Basmati and non-Basmati varities. GroupⅣ included domestic aroma rice except WAR34 and WAR35(Basmati varieties).

IL-34 (NIL) developed by introgressing chromosomal segment substitution from an accession of Oryza minuta (2n=48, BBCC, Acc. No. 101141) into the O. sativa subsp. japonica cv. Hwaseongbyeo, showed significantly higher number of spikelets per panicle (SSP) than the recurrent parent Hwaseongbyeo. QTL analysis in F2 generation derived from the cross between IL-34 and Hwaseongbyeo revealed that ssp7, a QTL was located in the pericentromeric region of chromosome 7. The frequency distribution of spikelets per panicle followed 3:1 ratio for single locus segregation. The additive effect of the O. minuta allele at the QTL was 23 spikelets per panicle, and 43.6% of the phenotypic variance could be explained by the segregation of marker RM21596. To clarify whether ssp7 could be dissected genetically, we carried out fine-scale mapping with 3,700 F2 plants derived from the cross between IL-34 and Hwaseongbyeo using markers flanking spp7. 186 F2 plants having informative recombination breakpoints within the region flanked by two SSR markers RM500 and RM21615 were identified and used for fine mapping of ssp7. ssp7 was mapped between the SSR markers RM21596 and RM418 which was approximately 441kb in length based on the physical map of the region. Of great interests, the QTL region also had effects on primary branch number (PB), grains per panicle (SP) and grain yield (YD). These results are very useful for transferring or pyramiding ssp7 by molecular marker assistant selection in rice breeding programs.

Grain weight (GW) or grain size is the most important target not only as a major component of grain yield, but also associated with the cooking quality in rice breeding program. In a previous study, two loci for grain weight, gw8 and gw9, have been fine map to about 306.4kb and 37.4kb, respectively, in backcross populations derived from a cross between the Korean japonica cultivar Hwaseongbyeo and Oryza rufipigon (IRGC 105491). Both O.rufipogon alleles increased GW in the Hwaseongbyeo background despite the fact that O. rufipogon was the small-seeded parent. To test the effect of pyramiding the QTLs for grain weight, an F2 population consisted of 226 individuals was developed derived from the cross between the two QTLs (gw8 and gw9), and used MAS to select nearly isgenic lines for two QTLs and a pyramiding line. Molecular genotyping of F2 population revealed the existence of interaction between gw8 and gw9. Moreover, the interaction was also confirmed by phenotypic analysis of four QTL-NILs. The results suggest that epistasis interaction is important genetic basis in determining yield traits in rice.

Field resistance is defined as the resistance that allows effective control of a parasite under natural field condition and is durable when exposed to new races of that parasite. To identify the genes for field resistance against rice blast, quantitative trait loci (QTLs) conferring field resistance in japonica rice cultivars were detected and mapped using SSR markers. QTL analysis was carried out in 190 RILs population from the cross between Suweon365 (moderately resistance) and Chucheong (highly susceptible). Fourteen QTLs for nine blast races inoculated were detected on chromosomes 1, 2, 4, 5, 6, 7, 11 and 12. They explained from 6.4 to 39.7% of total phenotypic variation. Eight QTLs for blast nursery screening in 4 regions for three years were detected on chromosomes 1, 2, 4, 5, 11 and 12. The phenotypic variation was explained by each QTL ranged from 5.9 to 38.0%. Three BC2F5 backcrossed progeny lines were developed to transfer the QTLs into the susceptible cultivar Chucheong as a recurrent parent. A NIL4 containing two QTLs Qbl6.2 and Qbl7 for blast races showed the reaction 6 to 7 in blast nursery in 2007 and 2008, respectively. Two lines NIL143 and NIL93 containing Qbl11.2 and Qbl12.1 for QTLs related with field resistance, respectively, were 3 to 4 reactions in blast nursery.

This study was conducted to provide the fundamental data based on the agronomic, phsyco-chemical characteristics, and quntification of volatile compounds of aroma rice germplasms. Among the 104 rice germplasm, five accessions of domestic aroma rice, 14 accessions of widely cultivated rice, and 60 accessions of foreign aroma rice were selected with excellent agronomic traits, high fertility and germination rate. The average amylose content of foreign aroma rice was higher than domestic aroma rice and widely cultured domestic rice. The domestic aroma rice was shown low protein and the foreign Indica types of aroma rice exhibited a wide range of protein contents. The foreign aroma rice were distributed a variable range of ADV value and lower than the both domestic aroma rice and widely cultured domestic rice. And it shown the difference aspect of amylograms according to the eco-type of the domestic and foreign aroma and the general rice, and it was distinguishable in difference of the aspect of the endosperm of rice as non-glutinous rice, waxy rice, and middle-waxy rice. The optimal extraction conditions of 2-Actyl-1- Pyrroline is recommended that five second grinding time, using 100 % ethyl alcohol, at 90℃ for 30 minutes. The domestic and the foreign aroma rice has more than mild aroma grade. A total 30 accession of aroma rice germplasm selected based on their 2AP concentration, aroma grade and agronomic traits. A total of 158 volatile and semi-volatile compounds were identified from 30 accessions of aroma rice germplasm, including 32 alcohols, 25 acids, 25 ketones, 21 hydrocarbon, 18 esters, 16 aldehydes, 4 ethers, 5 amines, 2 phenols, 2 bases, and 8 miscellaneous compounds. The thirty aroma rice germplasms could be classified into five groups according to the major odor or aroma compounds.

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.

Awn, one of the domestication-related traits in rice might play an important role in seed dispersal. In a previous study, one major QTL, awn8 was detected on chromosome 8 using 120 RILs and 62 ILs derived from a cross between Hwayeongbyeo and O. rufipogon Griff. (Acc. W1944). We developed 140 BC1F3, 341 BC1F4 and 1533 BC1F5 plants from selfing of one plant selected from former generation. Each of selected plant was Hwayeongbeyo/W1944 heterozygous in the target region of chromosome 8. The Target marker(RM256) significantly linked to awn8 explained 60.3% of the total phenotypic variance in BC1F4 generations and the W1944 allele increased awn length. Using several substitution mapping, The awn8 QTL could be narrow down to the interval between RM23338-RM5485, with a distance of about 85.29kb. Total of ten genes were predicted in this region. At the same time, 34 BC3F5 lines were developed as the diverse NILs on chromosme 8. Using these NILs, One QTL for primary branch was detected in the target region and W1944 allele increased branch number. Characterization of the awn8 QTL would contribute the understanding of rice domestication and evolution and additional experiment would be need to be clarified whether awn8 and pb8 was due to linkage drag of independent genes or pleiotropic effect of the same gene.

In the previous study, 141 BC3F2 lines from a cross between the Oryza sativa cv. Milyang 23 and O. glaberrima were used to identify favorable wild QTL alleles for yield component traits. In this study, we carried out QTL analysis of four grain morphology as well as four yield component traits using 141 BC3F5 lines from the same cross and compared QTLs detected in two different generations. The mean number of O. glaberrima segments in the 141 BC3F5 lines ranged from 1 to 13 with 2.69 and 5.71 of the average means of homozygous and heterozygous segments, respectively. There was a three-fold difference in the number of QTLs detected for four traits commonly evaluated in two generations (seven QTLs in the BC3F5 vs 21 in the BC3F2 population). The percentages of the phenotypic variance explained by QTLs in the BC3F5 population were similar to or less than those in the BC3F2 population. This is probably due to the difference in the genetic composition of two populations and the environmental effects. The locations of the QTLs commonly detected in both generations were in good agreement except for one QTL for spikelets per panicle. The yield QTL, yd3 was colocalized with the spikelets per panicle, spp3. Yield increase at this locus is due to the increase in spikelets per panicle, because both traits were associated with increase in spikelets per panicle and yield due to the presence of an O. glaberrima allele. Clusters of QTLs for grain morphology traits were observed in two chromosome regions. One cluster harboring five QTLs near SSR markers RM106 and RM263 was detected on chromosome 2. This population would serve as a foundation for development of the introgression line population from a cross between Milyang 23 and O. glaberrima.

Heading date in rice is a complex trait that is governed by multiple genes and environmental factors, such as day-length, temperature, and soil conditions. The genetic studies using DNA markers have facilitated the genetic dissection of heading date and many quantitative trait loci (QTLs) for heading date have been identified using several mapping population. In a previous study, a new quantitative trait loci (QTLs) for heading date have been identified using several mapping population. In a previous study, a new for heading date was detected near SSR marker RM215 on chromosome 9 using an advanced backcross line, WH29001, developed by introgressing chromosomal segments from an accession of Oryzaminuta (2n=48, BBCC, Acc. No.101141)into the O. sativa subsp. japonica cv. Hwaseongbyeo. The O. minuta allele of QTL contributed to an increase in heading date. To clarify whether dth9 could be dissected genetically, a high-resolution linkage mapping of dth9 was performed using alarge F2 population derived form the cross between one F4 plant which was homozygous for O.minuta in the target region RM5661-RM215 on chromosome9 and Hwaseongbyeo. Days to heading in the F2 population showed continuous variation rang form 102 to 113 days. The dth9 QTL further narrowed down at the interval between the SSR marker RM1553 and RM215 which was approximately 403kb in length based on the physical map of the region. The QTL for heading date(dth9) had not been detected in previous QTL studies between Oryza cultivars, indicating the existence of potentially novel alleles from O. minuta.