There is a great consideration on rice eating quality aside from improving its tolerance to various stresses. High yielding and pest and disease tolerant rice is highly desirable but it is more commercially important if it also has a high eating quality. There are various factors contributing to the good eating quality of rice. This study focuses on modifying the expression of GBSS1 genes which are responsible for amylopectin and amylose synthesis in rice by using RNAi and antisense techniques. We have developed 40 transgenic plants with RNAi-GBSS1 gene and 60 transgenic lines with antisense-GBSS1 gene. The transgenic plants show diverse amylose contents in rice seed. We selected candidate lines according to PCR, RNA expression and amylose contents. A semi-quantitative RT-PCR was carried out to measure the expression level of GBSS1 gene at several time points after the flowering of transgenic plants. The expression level of GBSS1 gene in rice grains decreases over time and the mRNA expression among the transgenic plants were lower compare to its wild type. In the SEM analysis, the starch granule of wild type Gopumbyeo has very large structures accompanied with small ones around the area. However, the starch structures in transgenic plants were smaller and more uniform in size and shape throughout the viewing area

Tongil (IR667-98-1-2) rice, developed in 1972, is a high-yielding rice variety derived from a three-way cross between indica and japonica. Tongil contributed to staple food self-sufficiency of Korea, an achievement that was termed the ‘Korean Green Revolution’. In this study, we analyzed the nucleotide-level genome structure of Tongil rice and compared it to those of the parental varieties. A total of 17.3 billion Illumina Hiseq reads, 47× genome coverage, were generated from Tongil rice. Three parental accessions, two indica and one japonica types, of Tongil rice were also sequenced for approximately 30x genome coverage. A total of 2,149,991 SNPs were detected between Tongil and Nipponbare; the average SNP frequency of Tongil was 5.77 per kb. Genome composition based on the SNP data by comparing with the three parental genome sequences on sliding window of Nipponbare genome sequence revealed that 91.8% of the Tongil genome originated from the indica parents and 7.9% from the japonica parent, different from the theoretical expectation in a three-way cross, i.e., 75% indica and 25% japonica parental origins on average. Copy number of SSR motifs, ORF gene distribution throughout the whole genome, gene ontology (GO) annotation, yield-related QTLs or gene locations, and polymorphic transposon insertions were also comparatively analyzed between Tongil and parents using sequence-based tools. The results indicated that each genetic factor was transferred from parents into Tongil in proportion to the whole-genome composition. The Tongil rice is the first successful superior cultivar derived from indica × japonica hybridization in Korea. Defining of genome structure demonstrates that the Tongil genome is composed mostly of the indica genome with a small proportion of japonica genome introgression. This work was supported by a grant from the Next-Generation BioGreen 21 Program (Plant Molecular Breeding Center No. PJ008125), Rural Development Administration, Republic of Korea.

도정도에 따른 식미의 품종간 차이를 구명하기 위해 우선 식미 관능평가를 통해 상, 중, 하로 구분하여 각각 3개 품종씩 총 9개 품종을 이용하였다. 9개 품종들은 도정도 5.5∼13.5%별 이화학특성 및 식미 관능평가를 분석하였다.식미 관능검정에 의한 식미총평은 도정도 90.5%와 88.5%에서 가장 좋았다. 품종별 식미총평이 도정도 90.5%에서 높은 A 유형과, 88.5%에서 높은 B 유형, 그리고 90.5%와 88.5%에서 유사한 C 유형과 같이 3가지 유형으로 구분이 되었다. 식미총평이 상인 일미벼, 고시히까리는 도정도 90.5%에서, 중인 추청벼, 동진벼 등은 88.5%에서 최고식미를 보였던 반면, 식미가 하인 팔공벼, 농호벼는 90.5%와 88.5%에서 모두 최고식미를 보여 도정도에 따른 식미 차이가 없는 것으로 평가 되었다. 3가지 유형별 식미총평과 이화학특성과 상관분석 결과, A유형은 Mg 함량이, B유형은 단백질 함량이, C유형은 K 함량이 상관의 유의성의 높았다. 유형별 식미총평과 관능평가 5가지 항목과의 상관 분석 결과, A유형은 찰기, B유형은 밥맛, C유형은 외관모양이 상관의 유의성에 크게 영향을 미친 것으로 나타났다. 따라서 A유형은 Mg 함량에 따른 밥의찰기와, B유형은 단백질 함량에 따른 밥맛과, C유형은 K 함량에 따른 밥의 외관모양에 각각 영향을 준 것으로 고찰 된다.

A field study was conducted to understand nitrogen use efficiency of high yielding Japonica rice varieties under three levels of nitrogen fertilizer (90, 150 and 210 kg N ha -1 ) in Iksan, Korea. Two high yielding rice varieties, Boramchan and Deuraechan, and an control variety, Dongjin2, were grown in fine silty paddy. Nitrogen use efficiencies (NUE) were 83.3, 56.3, and 41.2 in 90, 150, and 210 kg N ha -1 fertilizer level, respectively. Total nitrogen uptake varied significantly among nitrogen levels and varieties. Variety Dongjin2 showed the highest nitrogen uptake efficiency (NUpE), while Boramchan and Deuraechan showed higher nitrogen utilization efficiency (NUtE). However, Nitrogen harvest index (NHI) was higher in Boramchan (0.58) than Deuraechan (0.57) and Dongjin2 (0.53). Rough rice yield showed linear relationship with total nitrogen uptake (R 2 =0.72) within the range of nitrogen treatments. Boramchan produced significantly higher rough rice yield (8546 kg ha -1 ) which mainly due to higher number of panicles per m 2 compared to Deuraechan (7714 kg ha -1 ). Deuraechan showed higher number of spikelets per panicle, but showed lower yield due to lower number of panicle per m 2 . Rice varieties showed different nitrogen uptake ability and NUE at different nitrogen level. Plant breeders and agronomist should take advantage of the significant variations and relationships among grain yield, NUpE, and NUE.

쌀 가공산업을 활성화하고 소비를 촉진하여 국내 쌀 생산기반을 유지하기 위해서는 쌀가루 제분적성을 보유한 가공용벼 품종 개발이 시급하다. 농촌진흥청 국립식량과학원에서는 아지드화나트륨을 돌연변이원으로 활용하여 건식제분적합성을 보유한 분질배유 돌연변이 후대계통인 ‘Namil(SA)-flo1’를 육성한 바 있다. 본 연구는 염색체 상에서 ‘Namil(SA)-flo1’의 분질배유 특성을 지배하는 유전자위를 탐색하고자수행하였다. 주요 결과는 아래와 같다.1. ‘Namil(SA)-flo1’ × ‘밀양23호’로부터 유래한 F2 94 개체로부터 종자 분질립 비율을 검정하고 54개 SSR 마커의 유전자형을 검정하여 연관성분석(association analysis)을 수행한 결과 목표 유전자위는 5번 염색체 중하단부위로 추정되었다.2. 목표 부위의 SSR 마커 밀도를 높여 추가 연관성분석을 실시하였고, F2:3 종자 분질립 변이의 79.7%가 5번염색체 상의 RM164의 유전자형 변이에 의하여 설명된다는 것을 확인하였다.3. 이를 통하여 분질배유 지배 유전자위를 5번 염색체17.7~20.7 Mbp 부위로 추정하였으며, 추후 추가 분리집단을 이용하여 목표 유전자를 동정하고 쌀가루용품종 개발에 활용할 수 있는 핵산정밀표지인자를 개발할 계획이다.

The Brown planthopper (Bph) is one of the most serious pests of rice affecting rice yield and quality throughout the country. Combining the Bph resistance in the existing quality japonica cultivars is an important breeding target in Korea. Wide crosses using several strains of AA-genome wild rices, O.rufipogon have been used to produce the primary germplasm which is highly resistant to Bph. By repeated backcrossing, the resistance gene was introgressed in the background of two japonica cultivars, Ilpum and Hwaseong. Among the advanced backcross progenies, the ten BC2F3 lines were identified as the highest resistance in the comparative Bph bioassay with other resistant sources. The 24 polymorphic markers spanning the twelve chromosomes were tested for association with marker genotypes and resistance/susceptibility reaction in the 80 BC2F3 lines, RM3748 on the chromosome 7 showed the highest association.

‘Hyeonpum’ is a new japonica rice variety developed by a cross breeding between Iksan469 having a good canopy architecture and Sindongjin and Musashino 7 having a good eating-quality with a view to develop a new variety having high quality of grain and palatability by the rice breeding team of Rice Breeding and Cultivation Research Division, Department of Rice and Winter Cereal Crop, NICS, RDA in 2012. The heading date of this variety is August 18 and later than that of check variety, Nampyeongbyeo, by four days. ‘Hyeonpum’ has 74cm of culm length and 101 spikelets per panicle. This variety showed resistance to bacterial leaf blight and rice stripe virus, but susceptible to leaf blast and planthoppers. The milled rice of this variety exhibits translucent and very clear non-glutinous endosperm. ‘Hyeonpum’ has much better palatability of cooked rice than that of Nampyeongbyeo. The whole grain rate of milled rice and milled rice recovery of ‘Hyeonpum’ are slightly higher than those of Nampyeongbyeo as 91.8% and 75.2% respectively. The yield of ‘Hyeonpum’ is 5.6 MT/ha in milled rice. ‘Hyeonpum’ could be adaptable to the southern part plain area of Pyeongtaek and southwestern costal areas in Korea.

본 연구는 우리나라 벼흰잎마름병 균주에 대한 인디카형과 자포니카형의 단일 저항성 유전자의 반응과 이들의 집적 효과를 비교 분석하고 자포니카형의 유망 조합을 제시하여 향후 우리나라 환경 여건에 효과적인 저항성 품종을 육성하고자 수행하였다. 단일 저항성 유전자 계통중 Xa1, Xa3, Xa21은 생태형 간에 차이가 없었으나 Xa4와 xa5는 자포니카에 비해 인디카형에서 저항성이 강하였다. 인디카형과 자포니카형에서 모두 저항성 유전자가 집적되었을 경우에 단일 또는 두 개의 저항성 유전자에 비해 저항성이 정도가 증가하거나, 저항성 수준이 높은 유전자가 저항성 수준이 낮거나 균계 특이적 이병성을 나타내는 저항성 유전자를 보완하는 효과를 나타냈다. 자포니카형에서 새롭게 확인된 저항성 유전자 집적 조합인 Xa3+Xa21, xa5+Xa21과 Xa3+xa5+Xa21은 우리나라 우점 균주와 16개 균주에 대해서 저항성이었으며 현재 우리나라 벼흰잎마름병 저항성 육종에서 주력 저항성 조합으로 이용되고 있는 Xa3+xa5 보다 높은 수준의 저항성을 나타냈다. 이들 저항성 유전자 집적 조합은 균계 분화 등에 따른 저항성 붕괴에 안정적으로 대응할 수 있고 저항성을 효과적으로 강화할 수 있는 유망 조합으로 생각되어 자포니카 벼흰잎마름병 저항성 증진을 위한 목표 조합으로 설정하여 육종사업을 수행하겠다. 

조생종 벼 품종인 오대, 운광과 HR28021-AC16 계통에 대한 벼흰잎마름병 저항성 유전자분석과 K1과 K3a 균계를 접종한 후에 수량 및 품질 관련 형질들의 변이에 대하여 분석하였다. 오대는 저항성 유전자를 보유하지 않는 것으로 나타났고, 운광은 Xa3 유전자를, HR28021-AC16은 Xa21 유전자를가지는 것으로 확인되었다. 오대는 K1과 K3a 균계 모두에 이병성을 보였고, 운광은 K1에는 저항성을 K3a에는 이병성을보였다. HR28021-AC16은 K1 균계에는 이병성을 나타냈고K3a 균계에는 저항성 반응을 보였다. 균계접종에 의한 이병성 정도와 2차 감염 정도로 볼 때, K3a 균계가 K1 균계에 비해 병원성이 강한 것으로 나타났다. K1과 K3a 균계 접종에따른 생산력검정시험에서 균계 처리와 반응에 의해 변이가발생한 형질들 중에 등숙률, 정현비율, 현미수량과 완전미도정수율은 서로 간에 정의 상관관계를 나타냈으며, 이들 형질들과 현미 및 백미 단백질 함량은 부의 상관관계를 나타냈다.사미는 등숙률 및 완전미도정수율과 부의 상관관계를 나타냈다. 주성분분석에서 주성분 1을 기준으로 등숙률, 정현비율,현미수량 및 완전미도정수율과 사미, 현미 및 백미 단백질 함량이 다른 방향성을 나타냈고, 주성분 2를 기준으로는 등숙률과 사미가 다른 방향성을 나타냈다. Xa21 유전자를 가지고있는 HR28021-AC16은 K3a에는 저항성 반응을 보였으나K1 균계 접종구에서는 등숙률, 정현비율, 현미수량 및 완전미도정수율은 감소하였고 사미는 증가하는 등 이병성 반응을나타냈다. Xa21 유전자는 최근 큰 피해를 주는 K3a 균계에대해 강한 저항성을 보이나, 우리나라 우점 균계인 K1에 이병성을 보이기 때문에 K1 균계에 저항성인 다른 유전자와의집적을 통한 활용이 안정적인 저항성 증진에 효과적인 것으로 나타났다.

Plant transformation systems have been developed using several different approaches, and the development of reliable and efficient transformation systems is still one of the most important breakthroughs in molecular biology and biotechnology of rice. However, there are many cultivars in rice and transformation efficiency is dependent on the cultivar. The conventional Agrobacterium-mediated rice transformation system using secondary calli requires 14-16 weeks for establishing transgenic plantlets, and it is thought that somaclonal variation through the Tos17 retrotransposon occurs during the tissue culture stage. Here, we modified an Agrobacterium-mediated transformation system in rice cultivar Dongjin, adding an endosperm removal step that is critical to transformation frequency and changing the Agrobacterium strain and media composition. This method increased transformation efficiency and stability. These results will provide valuable information for scientists to use a reliable and efficient rice transformation system.

‘보람찬’품종은 국립식량과학원 벼맥류부에서 2009년도에 육성한 중만생 양질 내병성 품종으로 출수기는 보통기 다비재배에서 8월 16일로 한마음보다 1일 늦은 중만생종이다. 쌀은 복백이 약간 있으나 아밀로스 함량이 18.7%로 밥맛이 좋은 편이고, 도열병, 흰잎마름병 레이스 Kl-3 및 줄무늬잎마름병에는 저항성이나 멸구류에는 약하다. 유묘 내냉성은 출수지연일수가 13일로 한마음 23일에 비하여 짧고 임실률은 41%로 약간 높다. 쌀수량은 보통기 다비재배에서 7.33 T/ha로 한마음보다 9% 증수되었고 적응지역은 중부이남 평야지 l, 2모작지이다.

Heterosis describes the increased performance of F1 hybrid plants in terms of increased biomass, yield, vegetative growth rate, and tolerance against biotic and abiotic stresses as compared with their inbred parents. Two sets of rice materials, 166 RILs derived from a cross between Milyang 23 (Korean indica-type rice) and Tong 88-7 (japonica Rice), and BC1F1 hybrids derived from crosses between the RILs and the female parent, Milyang 23, were produced to identify QTLs for heterosis of yield and yield-related traits. The QTLs were detected from three different phenotype data sets including the RILs, BC1F1 hybrids, and mid-parental heterosis data set. A total of 57 QTLs were identified for nine traits. Of eight QTLs detected for yield heterosis, five overlapped with other heterosis QTLs for yield-related traits such as spikelet number per panicle, days to heading, and spikelet fertility. Four QTLs for yield heterosis, gy1.1, py6, gy10, and py11, were newly identified in this study. We identified a total of 17 EpQTLs for yield heterosis that explain 21.4 ~ 59.0 % of total phenotypic variation, indicating that epistatic interactions may play an important role in heterosis.

The Brown planthopper (BPH) is one of the most serious pests of rice affecting rice yield and quality throughout the country. AA genome wild rice, O.rufipogon is a useful source of insect resistance to BPH. To broaden the BPH resistance in the existing quality japonica cultivars, crossess were made between a highly susceptible quality rice cultivar, Ilpumbyeo, and five accessions (acc.106109, 106286, 106424,105908,80671) of O.rufipogon. Among 126 F8 RIL lines evaluated for Bph resistance at NICS, the highly resistant 22 introgression lines were identified and Ilpumbyeo*2/O.rufipogon (acc.105908) showed different genotype at the marker loci of Bph1, Bph18 and the resistance reaction to BPH in the BC1F2 population fitted to 3:1 segregation mode, indicating the possible new dominant resistance gene might be involved. Polymorphism between Ilpumbyeo and resistant line was low with 36 (27%) SSR markers among 130 markers detected. Currently mapping population of BC2F2 is established and SSR marker analysis will be carried out to find out the resistance loci.

Rice is the most important crop as the staple food and two priorities in rice production are high yield and good quality in Korea. Far more improvements in grain quality, especially eating quality are required to meet the demand of consumers in rice producing areas. In the study presented here, a recombinant inbred lines (RILs) population derived from a cross between a temperate japonica and a tropical japonica and its genetic linkage map were employed to locate the QTL locus underlying six parameters of RVA profiles. Out of six RVA profile parameters, two characteristics, breakdown viscosity (BDV) and setback viscosity (SBV) are more correlated to eating quality of cooled rice. A total of four QTLs for two RVA profile parameters were identified. Two QTLs, qBDV-6 and qBDV-9 for BDV were detected on chromosomes 6 and 9. These QTLs increased the BDV by 26.2 and 16.4 from Ilpumbyeo allele, respectively. A QTL, qBDV-6 in the interval RM540-RM587 of the wx gene on chromosome 6 was reacted as a major QTL which could explain 26.2% of the total phenotypic variation. A QTL, qBDV-9 in the interval RM5688-RM444 explained 7% of the total variation as a minor QTL. Two QTLs, qSBV-6 and qSBV-9 for SBV also identified at the same region with QTLs of BDV on chromosomes 6 and 9. A QTL, qSBV-6 in the interval of the wx gene on chromosome 6 could explain 24.4% of the total phenotypic variation. A QTL, qSBV-9 in the interval RM5688-RM444 explained 8.2% of the total variation. These QTL region on chromosomes 6 and 9 would be use as useful marker to select elite lines of good eating quality in early generations in japonica rice breeding.

Near-isogenic lines (NILs) carrying bacterial blight resistance genes (Xa4, xa5 and Xa21) were developed in japonica rice using Suweon345 as genetic background. NILs were selected by gene specific DNA markers and inoculation of K1 or K3a race. NILs conferring Xa4 were resistant to K1, K2, K3, and moderately resistant to K3a. NILs conferring xa5 were resistant to K1, K2, K3, and K3a. NILs having Xa21 were susceptible to K1, while resistant to K2, K3 and K3a. Target genes of NILs with the genetic background of Suweon345 were also confirmed by using eleven Philippines races and International Rice Bacterial Blight (IRBB) NILs carrying Xa4, xa5 and Xa21. All NILs had no significant difference from their recurrent parents in the major agronomic traits except for panicle length and brown rice 1,000 grain weight. Heading date of NILs ranged from Aug. 10 to Aug. 11, which was similar to that of recurrent parent, Suweon345. Culm length, number of grains per panicle and ratio of ripened grain of NILs were similar to those of Suweon345. Milled rice of NILs was ranged from 4.82 to 4.93MT/ha. These NILs will be useful for improving resistance to K3a race of bacterial blight pathogens in Korean japonica cultivars.

본 연구를 통하여 조생 다수성 벼 품종인 남일벼의 돌연변이 후대계통으로 'Namil(SA)2652-RGA-l-l-l-l'의 계보를 지니며 Namil(SA)-flo1로 명명된 분질계통의 건식제분 적성과 쌀가루의 이화학적 특성과 호화특성 등을 평가하였다. 배유절단면의 전자현미경 관찰결과 원품종인 남일벼는 배유절단면이 부드러우며 다변각의 전분립들이 치밀하게 배열된 반면 Namil(SA)-flo1은 원형모양의 전분립들이 매우 성기게 배열되어있었다. Namil(SA)-flo1의 작물학적 특성은 남일벼와 유사하였으나 등숙비율과 천립중이 낮았으며 이러한 특성은 백미수량 감소로 이어짐을 알 수 있었다. 조직분석기들 이용한 곡립경도측정 결과 Namil(SA)-flo1는 3,417 g으로 남일벼 (7,526 g)의 45% 수준으로 매우 낮았다. 건식제분기인 Buhler 제분기를 이용해 동일조건에서 생산된 쌀가루들에 대한 입도분석결과 Namil(SA)-flo1는 평균 86.1um 로서 원품종인 남일벼 (109.1um )는 물론 화성벼(112.2um )나 설갱벼 (97.6um )보다 매우 고운입자로 이루어져 있음을 확인하였다. 건식제분에 의한 쌀가루의 손상전분량 역시 Namil(SA)-flo1가 5.1% 수준으로 남일벼 (9.2%), 화성벼(10.3%) 및 설갱벼(7.1%) 보다 매우 낮아 Namil(SA)-flo1의 높은 건식제분 적합성을 확인할 수 있었다. 반면 Namil(SA)-flol에서 생산된 쌀가루의 이화학적 특성과 호화특성은 원품종인 남일벼의 고유한 특성을 견지하고 있는 것으로 사료되었다.

‘한설’은 1997년 고품질 극조숙 안전 다수성 품종을 육성할 목적으로 양질 극조숙인 ‘진부24호’를 모본으로 초형이 좋고 극조숙 내냉 다수성 계통인 ‘진부25호(운두벼)’를 부본으로 인공교배하여 2009년 육성한 극조숙 고품질 내냉성 벼 품종으로 주요 특성과 수량성을 요약하면 다음과 같다. 1. 출수기는 7월 25일로 ‘진부벼’보다 4일 정도 빠른 극조생종이며, 간장은 65 cm로 ‘진부벼’보다 약간 작고, 주당 이삭수는 12개, 이삭당 벼알수는 99