초록 ▼

야생유전자원의 유용유전자를 활용하기 위하여, 야생벼의 염색체단편이 최소로 이입된 근동질계통을 육성하고 수량안정성 관련 형질연관 QTL을 탐색하였다. ‘화성’/‘O. rufipogon’ 조합 계통을 이용하여 염색체 9번의 Ascorbate peroxidase 유전자가 출수기, 종자중 등 수량구성요소에 관여함을 밝히고, 염색체 8번의 O. rufipogon 단편에 위치하는 QTL(gw8.1) 이화성의 배경에서 종자길이를 증가시킴을 확인하였다. 저온발아성에 관여하는 유전자 LTG3의 신규 대립유전자의 기능을 분석하고, 신규유전자 ltg1

야생유전자원의 유용유전자를 활용하기 위하여, 야생벼의 염색체단편이 최소로 이입된 근동질계통을 육성하고 수량안정성 관련 형질연관 QTL을 탐색하였다. ‘화성’/‘O. rufipogon’ 조합 계통을 이용하여 염색체 9번의 Ascorbate peroxidase 유전자가 출수기, 종자중 등 수량구성요소에 관여함을 밝히고, 염색체 8번의 O. rufipogon 단편에 위치하는 QTL(gw8.1) 이화성의 배경에서 종자길이를 증가시킴을 확인하였다. 저온발아성에 관여하는 유전자 LTG3의 신규 대립유전자의 기능을 분석하고, 신규유전자 ltg1을 탐지하고 후보유전자를 밝히기 위해 T-DNA 삽입변이체 등을 검정하고 있다.화성/O. minuta 후대계통을 이용하여 까락발달에 관여하는 신규유전자(awn9)를 탐지하고 유전자분리를 위한 고밀도지도를 작성하고 있다.
화성/O. grandiglumis 후대를 이용하여 GW2 (grain width 2) 유전자가 종자중 외에도 엽록소함량을 조절함을 밝혔고, GW2 유전자의 다면발현 효과를 분석 중이다. Nipponbare/Kasalath 조합 근동질계통을 이용, 중배축신장에 관여하는 QTL을 탐지하고 초엽 신장성과의 관계를 밝혀 직파재배적성 품종육성을 위한 정보를 획득하였다. 이러한 결과들을 종합하여 7건의 논문, ‘식물체의 초장, 종자 크기 및 출수기를 조절하는 야생벼 유래 APX9 유전자 및 이의 용도’ 등 3건의 특허 등록, 국내외 학술발표, 종자분양 등의 성과를 도출하였다. 근동질계통은 다양한 표현형을 조절하는 양적형질유전자의 탐색 및 이용에 귀중한 자원이 될 것이다.

(출처 : 요약서 3p)

Abstract ▼

□ Purpose&Contents
The objectives of the present study were to develop NIL(nearly isogenic lines) from interspecific crosses (1) to identify trait-improving QTL derived from the wild and the weedy rice that are associated with improved agronomic performance in the cultivated background, (2) to de

□ Purpose&Contents
The objectives of the present study were to develop NIL(nearly isogenic lines) from interspecific crosses (1) to identify trait-improving QTL derived from the wild and the weedy rice that are associated with improved agronomic performance in the cultivated background, (2) to develop DNA markers to QTL of agronomic importance and isolate and characterize genes underlying these traits, and (3) to select promising lines .from the NIL populations based on repeated backcrossing and marker-assisted selection.

□ Results
1. Heading date and a cluster of yield QTL
A cluster of yield-related QTL in a near-isogenic line (NIL) from an interspecific cross between Oryza sativa spp. japonica cultivar ‘Hwaseong’ and O. rufipogon. wasreported in the previous study. Map-based cloning and transgenic approaches revealed that APX9 (LOC_Os09g36750) encoding an L-ascorbate peroxidase 4 is associated with this cluster. Sequence differences in the APX9 promoter and coding regions were observed between the two parental lines including a 3-bp InDel leading to the addition of a valine in Hwaseong. NIL plants showed higher expression of APX9 in various tissues than Hwaseong. We generated APX9 over-expression (OE) transgenics in the Hwaseong background. APX9-OE plants showed taller stature and delayed heading compared to Hwaseong, whereas T-DNA knock-out mutants showed reduced plant height compared to the wild type. These results confirm that APX9 is the causal gene for the QTL cluster. NIL had higher antioxidant ability and APX activity than Hwaseong leading to increased drought tolerance seedlings. Sequence analysis of APX9 from 303 rice accessions revealed that the 3-bp InDel clearly differentiates japonica (APX9^HS ) and O. rufipogon (APX9^OR) alleles. Indica shared both APX9^HS and APX9^ORalleles suggesting that APX9^HS was introgressed into indica followed by crossing. The finding that O. rufipogon accessions with different origins carry APX9^OR strongly suggests that the 3-bp insertion was specifically selected in japonica during domestication. In this study, we demonstrated that a pleiotropic gene APX9 acts as a major regulator of plant development by controlling a valuable suite of agronomically important traits in rice.

2. A RING-type E3 ubiquitin ligase, OsGW2 controls chlorophyll content and dark-induced senescence in rice
Leaf senescence is the final stage of plant development. Many internal and external factors affect the senescence process in rice (Oryza sativa L.). In this study, we identified qCC2, a major QTL for chlorophyll content using a population derived from an interspecific cross between O. sativa (cv. Hwaseong) and O. grandiglumis.
The O. grandiglumis allele at qCC2 increased chlorophyll content and delayed senescence. GW2 encoding E3 ubiquitin ligase in the qCC2 region was selected as a candidate for qCC2. To determine if GW2 is allelic to qCC2, a gw2-knockout mutant (gw2-ko) was examined using a dark-induced senescence assay.
gw2-ko showed delayed leaf senescence in the dark with down-regulated expression of senescence-associated genes (SAGs) and chlorophyll degradation genes (CDGs).
Association of the GW2 genotype with the delayed senescence phenotype was confirmed in an F₂ population. RNA-seq analysis was conducted to investigate 30-day-old leaf transcriptome dynamics in Hwaseong and a backcross inbred line, CR2002 under dark treatment. This resulted in the identification of genes involved in phytohormone signaling and associated with senescence. These results suggest that transcriptional regulation is associated with delayed senescence in CR2002 and RING-type E3 ubiquitin ligase GW2 is a positive regulator of leaf senescence in rice.

3. Characterization of a new qLTG3-1 allele for low-temperature germinability from a wild species Oryza rufipogon in rice
Background: Rice (Oryza sativa L.) is generally sensitive to low temperatures, and in production systems that use direct-seeding, low-temperature germinability (LTG) is a desired trait. Previously, the QTLs, qLTG1 and qLTG3, that control LTG, were mapped using the BC₄F₈ population, which is a cross of Korean elite cultivar Hwaseong and O. rufipogon (IRGC 105491). We have characterized and analyzed the interactions between the two QTLs, by crossing TR20 that has O. rufipogon alleles at qLTG1 and qLTG3 in a Hwaseong background, with Hwaseong, to develop an F₂ population.

Results: The F₂ plants with both qLTG1 and qLTG3 alleles from O. rufipogon showed higher LTG scores, than the plants with only qLTG1 or qLTG3. No significant interactions between the qLTG1 and qLTG3 were observed, indicating that they may regulate LTG via different pathways. Based on its location, qLTG3 appears to be allelic with qLTG3-1, a major QTL known to control LTG. To investigate the genetic differences between the two parents, that were controlling LTG, we compared their qLTG3-1 sequences. In the coding region, three sequence variations leading to amino acid changes were identified between the Hwaseong and O. rufipogon. Of these, a non-synonymous substitution at the 62^nd amino acid site, had not previously been reported. To understand the cause of the LTG variations between the parents,we genotyped three sequence variations of qLTG3-1, that were identified in 98 Asian cultivated rice accessions (Oryza sativa L.). The 98 accessions were classified into 5 haplotypes, based on three variations and a 71-bp deletion. Mean low-temperature germination rates were compared among the haplotypes, and haplotype 5 (O. rufipogon-type) showed a significantly higher germination rate than haplotype 2 (Nipponbare-type), and haplotype 3 (Italica Livorno-type).

Conclusions: The O. rufipogon qLTG3-1 allele can be utilized for the improvement of LTG in rice breeding programs. Nearly isogenic lines harboring both qLTG1 and qLTG3-1 alleles from O. rufipogon, showed higher LTG scores than the NILs with qLTG1 or qLTG3-1 alone, and the two QTLs regulate LTG via different pathways.
To our knowledge, this is the first report to detect a new qLTG3-1 allele and analyze the interactions of the two LTG QTLs in a nearly isogenic background.

4. Fine Mapping of a Low-Temperature Germinability QTL qLTG1 Using Introgression Lines Derived from Oryza rufipogon
Low-temperature germinability (LTG) is an important trait for rice direct seeding at temperate and high-altitude region. Previously, five QTLs (quantitative trait loci) for LTG were detected using an interspecific cross population between the Korea japonica cultivar Hwaseong and Oryza rufipogon (IRGSP#105491). O. rufipogon alleles at all loci increased the germination rate at the 13℃ condition. In this study, we tried to confirm and fine-map qLTG1 located on the short arm of chromosome 1. To map the qLTG1, two introgression lines, TR5 and TR20 were crossed to Hwaseong to develop F_2:3 populations. QTL analysis confirmed the existence of the qLTG1 and it explained 55.5% and 29.9% of phenotypic variation in two populations,respectively. Substitution mapping using informative recombinant lines indicated that qLTG1 was located in 167-kb region between two SSR markers RM10310 and RM10326. This segment harbored 18 genes with nine of them were annotated with specific gene function. In addition, the O. rufipogon introgression in this region was associated with an increase in spikelets per panicle in the Hwaseong background. The results strongly indicate that the O. rufipogon alleles in will be a valuable source of genes in improving japonica rice for low-temperature germinability and yield. To our knowledge, this is the first report to fine-map qLTG1 associated with LTG in rice considering that no QTL for LTG has not been reported near this QTL region from other biparental populations.

5. Genetic Analysis of Seedling Traits Regulated by Light in Weedy Rice
The Korean weedy rice, PBR (photoblastic rice) was reported to have light-inducible seed germination (photoblastism) and long mesocotyl. In previous studies, we mapped two QTL each for photoblastism and mesocotyl length using progeny from a cross between Ilpumbyeo and PBR. One F8 line CR7124 having photoblastism and long mesocotyl, was chosen and crossed to Ilpumbyeo to produce 95 F3 lines for QTL mapping. Germination percentage of CR7124 and Ilpumbyeo was 3.3 ± 2.4% and 91.7 ± 7.1%, respectively in the dark condition. 95 F3 lines ranged from 28.6% to 100% in germination. For mesocotyl, Ilpumbyeo and PBR elongated up to 1.5 mm and 18.5 mm, respectively whereas 95 F3 lines ranged from 0.9 mm to 16.3 mm.
The mesocotyl length showed highly negative significant correlation with germination rate in dark condition (r = 0.70, P < 0.0001). QTL mapping using 95 F3 lines confirmed the linkage of two QTL for photoblastism and mesocotyl length on chromosome 1. Eight F4 lines with different PBR chromosome segments in the target region were used for substitution mapping of pbr1 and qMel-1. It appears that qMel-1 was located in the interval RM11252 - RM7419, a region of approximately 4.7 Mb. pbr1 was located in the interval between RM7202 and RM11729. Although further fine mapping of two QTL is necessary to know the relationship of these two traits, these results together with the highly significant correlation between two traits indicate that two QTL are linked. DNA markers linked to these QTLs would be useful in facilitating the selection of lines with enhanced mesocotyl elongation.

6. Characterization of quantitative trait loci for germination and coleoptile length under low-temperature conditions using introgression lines derived from an interspecific cross in rice
Previously, five putative quantitative trait loci (QTLs) for low-temperature germination (LTG) have been detected using 96 BC₃F₈ lines derived from an interspecific cross between the Korean japonica cultivar “Hwaseong” and Oryza rufipogon. In the present study, two introgression lines, CR1517 and CR1518, were used as parents to detect additional QTLs and analyze interactions among QTLs for LTG. The F₂ population (154 plants) along with parental lines, Hwaseong and O. rufipogon, were evaluated for LTG and coleoptile length under low-temperature conditions (13°C). Among five QTLs for LTG, two major QTLs, qLTG1 and qLTG3, were consistently detected at 6 and 7 days after incubation. Three minor QTLs were detected on chromosomes 8 and 10. Two QTLs, qLTG10.1 and qLTG10.2, showing linkage on chromosome 10, exerted opposite effects with the Hwaseong allele at qLTG10.2 and the O. rufipogon allele at qLTG10.1 respectively,in turn, increasing LTG. Interactions among QTLs were not significant, implying that the QTLs act in an additive manner. Near-isogenic line plants with the combination of favorable alleles from O. rufipogon and Hwaseong exhibited higher LTG than two introgression lines. With regard to coleoptile length, three QTLs observed on chromosomes 1, 3, and 8 were colocalized with QTLs for LTG, suggesting the pleiotropy of the single gene at each locus. According to the results, the introgression of favorable O. rufipogon alleles could hasten the development of rice with high LTG and high coleoptile elongation in japonica cultivars.

□ Expected Contribution
o The NILs developed in the study would be used as bridging lines for breeding purposes or directly as elite cultivars.
o The NILs would be useful in widening and enriching the diversity of cultivated rice cultivars.
o The NILs would be useful to isolate and characterize genes (QTLs) of agronomic impportance.

(출처 : SUMMARY 5p)

목차 Contents

• 표지 ... 1
• 제 출 문 ... 2
• 보고서 요약서 ... 3
• 국 문 요 약 문 ... 4
• Summary ... 5
• 목차 ... 9
• 제 1 장 연구개발과제의 개요 ... 10
• 제1절 연구 개발 목적 ... 10
• 제2절 연구 개발의 필요성 ... 10
• 제3절 연구개발 범위 ... 11
• 제 2 장 연구수행내용 및 결과 ... 12
• 제1절 연구 수행내용 및 결과 ... 12
• 제 3 장 목표달성도 및 관련분야 기여도 ... 54
• 제1절 목표대비 달성도 ... 54
• 제2절 정량적 성과(논문게재, 특허출원, 기타)를 기술 ... 55
• 제 4 장 연구 결과의 활용 계획 ... 56
• 제1절 연구개발 결과의 활용방안 ... 56
• 제2절 추가 연구의 필요성 ... 56
• 제3절 추가적인 연구 성과 ... 57
• 제 5 장 연구 개발 결과의 보안 등급 ... 58
• 제 6 장 연구시설·장비종합정보시스템에 등록한 연구시설·장비 현황 ... 59
• 제 7 장 연구개발과제의 대표적 연구실적 ... 60
• 제 8 장 기타사항 ... 61
• 제 9 장 참고문헌 ... 64
• 끝페이지 ... 68