• Title/Summary/Keyword: Mosaic

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A Statistical Analysis of Phenotypic Diversity Based on Genetic Traits in Barley Germplasms (특성평가 정보를 활용한 보리 유전자원 형태적 형질 다양성의 통계적 분석)

  • Yu, Dong Su;Shin, Myoung-Jae;Park, Jin-Cheon;Kang, Manjung
    • Korean Journal of Plant Resources
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    • v.35 no.5
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    • pp.641-651
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    • 2022
  • The biodiversity research of barley, a functional food, is proceeding to conserve germplasms and develop new cultivar of barley to improve its functional effects. In this study, with 25,104 barley germplasms in the National Agrobiodiversity Center, South Korea, the biodiversity index of species was much lower (1.17) than the origins (24.73) because of the presence of a biased species, Hordeum vulgare subsp. vulgare, but the species and origin of germplasms were significantly different with regard to genetic traits. In the clustering analysis based on genetic traits, we found that 97% barley germplasms could mostly be distributed between 1~7 clusters out of a total of 15 clusters; 'normal and uzu type', 'lodging', and 'loose smut' were commonly represented in the 1~7 clusters and some clusters showed specific differences in five genetic traits including 'growth habit'. In correlation of each genetic trait, the infection of 'barley yellow mosaic virus' was highly correlated to 'number of grains per spike'. '1000 grain weight' was weakly correlated with seven genetic traits including 'number of grains per spike'. Our analysis for barley's biodiversity can provide a useful guide to the species' phenotypes that need to be collected to conserve biodiversity and to breed new barley varieties.

Occurrence of Viruses and Viroids in Chrysanthemum Plants (Dendranthema morifolium) Cultivated in Yesan-gun, Chungcheongnam-do in Korea (충남 예산 지역의 국화에서 바이러스 및 바이로이드 병들의 발생 현황)

  • Yoon Hyun, Bang;Eun Gyeong, Song;Younghye, Lee;Ki Hyun, Ryu
    • Research in Plant Disease
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    • v.28 no.4
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    • pp.237-244
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    • 2022
  • Chrysanthemum plants are one of the most economically important plants in South Korea. Both virus and viroid can cause diseases and economic damage to the plants. In this study, we investigated the detection of seven viruses and two viroids in 350 chrysanthemum plants cultivated in Yesan-gun, Chungcheongnam-do. Two viruses, chrysanthemum virus B (CVB) and tomato aspermy virus (TAV), and two viroids, chrysanthemum chlorotic mottle viroid (CChMVd) and chrysanthemum stunt viroid (CSVd), were detected in this study. The two viruses were detected in six samples and one sample, respectively. The two viroids were detected in 97 samples and 21 samples, respectively. The nucleotide sequences of the CVB-CN-Y, TAV-CN-Y, CChMVd-CN-Y, and CSVd-CN-Y obtained in this study showed 83.7-86.9%, 99.2-100.0%, 94.4-99.5%, and 95.7-99.7% identity, respectively, compared to their other strains/isolates. The CVB-CN-Y and TAV-CN-Y showed the greatest nucleotide sequence homology to CVB-GS1 and three TAV isolates (TAV-V, TAV-P, and TAV-ChJ), respectively. The CChMVd-CN-Y and CSVd-CN-Y showed the greatest nucleotide sequence homology to CChMVd-Horst and four CSVd isolates (Au1.1, K4pop, Sagae, and Tochigi), respectively. This study is the report on the infection rate of viruses and viroids in chrysanthemum plants cultivated in Yesan-gun in 2021.

Molecular Breeding of Tobacco Plants Resistant to TMV and PVY (분자생물학적 TMV 및 PVY 저항성 연초 육종)

  • E.K. Pank;Kim, Y.H.;Kim, S.S.;Park, S.W.;Lee, C.H.;K.H.Paik
    • Proceedings of the Korean Society of Tobacco Science Conference
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    • 1997.10a
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    • pp.134-152
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    • 1997
  • Plant viruses of tobacco including tobacco mosaic virus (TMV) and potato virus Y (PVY) cause severe economic losses in leaf-tobacco production. Cultural practices do not provide sufficient control against the viruses. Use of valuable resistant cultivars is most recommendable for the control of the viruses. However, conventional breeding programs are not always proper for the development of virus-resistant plants mostly owing to the frequent lack of genetic sources and introduction of their unwanted properties. Therefore, we tried to develop virus-resistant tobacco plants by transforming commercial tobacco cultivars, NC 82 and Burley 21, with coat protein (CP) or replicase (Nlb) genes of TMV and PVY necrosis strain (PVY-VN) with or without untranslated region (UTR) and with or without mutation. Each cDNA was cloned and inserted in plant expression vectors with 1 or 2 CaMV 35S promotors, and introduced into tobacco leaf tissues by Agrobacterium tumefaciens LBA 4404. Plants were regenerated in kanamycin-containing MS media. Regenerated plants were tested for resistance to TMV and PVY In these studies, we could obtain a TMV-resistant transgenic line transformed with TMV CP and 6 genetic lines with PVY-VN cDNAs out of 8 CP and replicase genes. In this presentation, resistance rates, verification of gene introduction in resistant plants, stability of resistance through generations, characteristics of viral multiplication and translocation in resistant plants, and resistance responses relative to inoculum potential and to various PVY strains will be shown. Yield and quality of leaf tobacco of a promising resistant tobacco line will be presented.

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'Neulchan', a Middle-seed, Disease-resistant, and High-yield Soybean Cultivar for Soy-paste and Tofu (중립 내병 다수성 장류·두부용 콩 '늘찬')

  • Kim, Hyun Tae;Ko, Jong Min;Baek, In Youl;Han, Won Young;Yun, Hong Tai;Lee, Byoung Won;Shin, Sang Ouk;Seo, Jeong Hyun;Kim, Hong Sik;Kwak, Do Yeon
    • Korean Journal of Breeding Science
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    • v.51 no.4
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    • pp.475-481
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    • 2019
  • The soybean cultivar 'Neulchan' was developed for production of soy-paste and tofu. SS91501-9-1-1 and SS96205 (F2) were crossed in 1998, and F3 to F7 were selected by the pedigree method. A preliminary yield trial (PYT) and an advanced yield trial (AYT) were conducted from 2006 to 2008, and a regional yield trial (RYT) in nine regions was conducted from 2009 to 2011. In the RYT, 'Neulchan' was stable in variable environments and generated high yield. 'Neulchan' was determinate with white flower, light brown pod color, yellow spherical seed, and yellow hilum. Its flowering date and maturity date were Jul. 30 and Oct. 9, respectively. The plant height was shorter than that of 'Daewonkong' (a standard cultivar). 'Neulchan' had the same node number (14), higher first-pod height (12 cm), and lighter seed weight (21.7 g/100-seed weight) than those of 'Daewonkong' (14, 11, and 24.2 g/100-seed weight, respectively). 'Neulchan' had high resistance to bacterial pustule, and its resistance to soybean mosaic virus was similar to that of 'Daewonkong'. The yield and color of 'Neulchan' tofu were similar to those of 'Daewonkong' tofu, but the hardness was lower than that of 'Daewonkong' tofu. The soybean malt scent, fermented soybean yield, and γ-polyglutamic acid (γ-PGA) of 'Neulchan' were 3, 215%, and 24.6 mg/g, respectively. Its yield in adaptable regions was 307 kg/10a, higher than that of 'Daewonkong'. 'Neulchan' was expected to be cultivated and used widely for soy-paste and tofu production. (Registration No. 4904).

Preselection of Bovine Blastocysts Expressing Exogeneous Gene Following Microinjection (외래유전자를 주입한 소 수정란에서 형질전환가능 수정란의 선발)

  • 공일근
    • Korean Journal of Animal Reproduction
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    • v.21 no.2
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    • pp.167-176
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    • 1997
  • This study was carried out to evaluate the potential for preselection of transgenic embryos prior to transfer into recipient animals. In these experiments, I used a 3.2 kb transgene which contained the neomycin resistance gene (neo) and lac Z gene driven by the $\beta$ actin promoter (iacZ Ineo). Oocytes were aspirated from abattoir ovaries, matured in TCM-199 supplemented with 10% fetal bovine serum (FBS), 5 ${\mu}\textrm{g}$/ml LH, 0.5 ${\mu}\textrm{g}$/ml FSH, 100 unit/ml penicillin, and 100 ${\mu}\textrm{g}$/ml streptomycin for 22 to 24 hrs then inseminated with a sperm suspension of 1 X 10$^6$ sperm/ml containing 5 ${\mu}\textrm{g}$/ml of heparin. At 18-20 hrs after insemination, cumulus cells were removed by vortexing and pronuclei of centrifuged zygotes microinjected with the lacZ/neo construct (3 ng/$\mu$l). All cultures were carried out in CR1aa with transfected BRL monolayers containing 3 mg/ml BSA, 20 $\mu$/ml NEM amino acids and 40 $\mu$I/ml BME amino acids. To identify the appropriate concentration of G418 for selection, non-microinjected zygotes were cultured in the presence of 0, 50, 100 and 200 $\mu$g/ml of G418. After 8 days of culture in these treatments, 44/145 (30.3%), 13/150 (8. 7%), 1/151 (0.7%) and 0/134 (0.0%) devel-oped to the blastocyst stage in 0, 50, 100 and 200 $\mu$g/ml of G418, respectively. A total of 1,127 zygotes were microinjected and placed into culture (without G418) and subsequently 710 (63.0%) cleaved. At 48 hrs post-injection, embryos ($\geq$2-cell) were randomly assigned to control (medium alone) or G418 (100 ${\mu}\textrm{g}$/ml) treatments. A control culture of 740 non-microinjected embryos from the same replicates of embryos were also placed into control medium. After 8 days in culture, 54/343 (15.7%) and 22/367 (6.0 %) of the microinjected embryos developed to the blastocyst stage in control and G418 media, respectively. A total of 151/740 (27.2%) of the non-microinjected embryos placed in the control medium developed to the blastocyst stage. The blastocysts in the control treatment had a mean of 70.7 ${\pm}$ 4.7 cells of which 23.1 ${\pm}$ 2.6 (32.7%) stained for $\beta$-Gal activity. B1astocysts in the G418 treatment had a mean of 48.8${\pm}$7.5 cells of which 40.3 ${\pm}$ 4.1 (82.6%) stained for $\beta$-Gal ac tivity (P<0.05). In the control treatment 26 of 30 (87.0%) blastocysts had some cells with $\beta$-Gal activity while all of the blastocysts in the G418 treatment had some cell with $\beta$-Gal ac tivity (P<0.05). However, ICM colonies in either control or G418 treatments were not expressed any epiblast cell except of trophetoderm celIs. The $\beta$-actin promoter/lacZ gene may not be e expression or silence expression in epiblast cells These results clearly show an enrichment of blastocysts expressing the transgene in the majority of their cells after culture in the presence of G418. The exogeneous gene was not express a and silence in ICM colonies especiallly epiblast cells except of trophectederm cells. Even though the higher rate cell number expressed of exogeneous gene in the G418 treatments, a total cell number was decrease significantly (P<0.05) of which might be also drop of the establishment of ES like-cell colonies and production of transgenic animals. However, futher studies need to determine the viability of these selected embryos and the avability of production of transgenic offspring.

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CAS 500-1/2 Image Utilization Technology and System Development: Achievement and Contribution (국토위성정보 활용기술 및 운영시스템 개발: 성과 및 의의)

  • Yoon, Sung-Joo;Son, Jonghwan;Park, Hyeongjun;Seo, Junghoon;Lee, Yoojin;Ban, Seunghwan;Choi, Jae-Seung;Kim, Byung-Guk;Lee, Hyun jik;Lee, Kyu-sung;Kweon, Ki-Eok;Lee, Kye-Dong;Jung, Hyung-sup;Choung, Yun-Jae;Choi, Hyun;Koo, Daesung;Choi, Myungjin;Shin, Yunsoo;Choi, Jaewan;Eo, Yang-Dam;Jeong, Jong-chul;Han, Youkyung;Oh, Jaehong;Rhee, Sooahm;Chang, Eunmi;Kim, Taejung
    • Korean Journal of Remote Sensing
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    • v.36 no.5_2
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    • pp.867-879
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    • 2020
  • As the era of space technology utilization is approaching, the launch of CAS (Compact Advanced Satellite) 500-1/2 satellites is scheduled during 2021 for acquisition of high-resolution images. Accordingly, the increase of image usability and processing efficiency has been emphasized as key design concepts of the CAS 500-1/2 ground station. In this regard, "CAS 500-1/2 Image Acquisition and Utilization Technology Development" project has been carried out to develop core technologies and processing systems for CAS 500-1/2 data collecting, processing, managing and distributing. In this paper, we introduce the results of the above project. We developed an operation system to generate precision images automatically with GCP (Ground Control Point) chip DB (Database) and DEM (Digital Elevation Model) DB over the entire Korean peninsula. We also developed the system to produce ortho-rectified images indexed to 1:5,000 map grids, and hence set a foundation for ARD (Analysis Ready Data)system. In addition, we linked various application software to the operation system and systematically produce mosaic images, DSM (Digital Surface Model)/DTM (Digital Terrain Model), spatial feature thematic map, and change detection thematic map. The major contribution of the developed system and technologies includes that precision images are to be automatically generated using GCP chip DB for the first time in Korea and the various utilization product technologies incorporated into the operation system of a satellite ground station. The developed operation system has been installed on Korea Land Observation Satellite Information Center of the NGII (National Geographic Information Institute). We expect the system to contribute greatly to the center's work and provide a standard for future ground station systems of earth observation satellites.

Thinking in Terms of East-West Contacts through Spreading Process of Sarmathia-Pattened Scabbard on Tillya-Tepe Site in Afghanistan (아프가니스탄 틸랴 테페의 사르마티아(Sarmathia)식 검집 패용 방식의 전개 과정으로 본 동서교섭)

  • Lee, Song Ran
    • Korean Journal of Heritage: History & Science
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    • v.45 no.4
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    • pp.54-73
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    • 2012
  • In this article, we examined the patterns of activities of the Sarmathians though in a humble measure, with a focus on the regions where the Sarmathian sheaths spreaded. One of the main weapons the mounted nomads like the Scythias, the Sarmathians, and the Alans used at war was a spear. Though complementary, a sword was the most convenient and appropriate weapon when fighting at a near distance, fallen from the horse to the ground. The Sarmathian swords continued the tradition of the Akinakes which the Scythias or the Persians used, but those of the Sarmathians showed some advances in terms of the easiness with which a sword was drawn out from a sheath, and the way the sheaths were worn to parts of a human body. It turns out that the Sarmathian sheaths, which were designed for the people to draw swords easily, having the sheaths attached to thighs through 4 bumps, spread extensively from Pazyryk, Altai, to South Siberia, Bactria, Parthia and Rome. The most noteworthy out of all the Sarmathian sheaths were the ones that were excavated from the 4th tomb in Tillatepe, Afghanistan which belonged to the region of Bactria. The owner of the fourth tomb of Tilla-tepe whose region was under the control of Kushan Dynasty at that time, was buried wearing Sarmathian swords, and regarded as a big shot in the region of Bactria which was also under the governance of Kushan Dynasty. The fact that the owner of the tomb wore two swords suggests that there had been active exchange between Bactria and Sarmathia. It seemed that the reason why the Sarmathians could play an important role in the exchange between the East and the West might have something to do with their role of supplying Chinese goods to Silk Road. That's why we are interested in how the copper mirrors of Han Dynasty, decoration beads like melon-type beads, crystal beads and goldring articulated beads, and the artifacts of South China which produced silks were excavated in the northern steppe route where the Sarmathians actively worked. Our study have established that the eye beads discovered in Sarmathian tomb estimated to have been built around the 1st century B.C. were reprocessed in China, and then imported to Sarmathia again. We should note the Huns as a medium between the Sarmathians and the South China which were far apart from each other. Thus gold-ring articulated beads which were spread out mainly across the South China has been discovered in the Huns' remains. On the other hand, between 2nd century B.C. and 2nd century A.D. which were main periods of the Sarmathians, it was considered that the traffic route connecting the steppe route and the South China might be West-South silk road which started from Yunnan, passed through Myanmar, Pakistan, and Afghanistan, and then went into the east of India. The West-south Silk road is presumed to have been used by nomadic tribes who wanted to get the goods from South China before the Oasis route was activated by the Han Dynasty's policy of managing the countries bordering on Western China.

Investigation on Korean Local Maize Lines V. Variabilities of Plant Characters of Multi-eared and Tillered Lines(MET) (재래종 옥수수 수집종에 대한 특성조사 제5보 다수다벽 재래종 옥수수계통의 특성변이)

  • Choe, B.H.;Park, J.S.;Kim, Y.R.;Park, K.Y.
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.26 no.1
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    • pp.56-68
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    • 1981
  • A maize line was selected in 1979 among 1000 Korean local maize lines collected in 1977. The selected maize line was characterized by having three to four tillers and eight to 10 ears on each individual plant. The line was assumed to have a great potential as a silage crop. The investigation was conducted as one of the serial studies on the Korean maize collected lines to provide basic information on the genetic variabilities of the multi-eared and tillered (MET) line and on other agronomic characters, prior to use the line as material for future breeding works for silage crop. The MET line and Suwon #19, single cross hybrid, as check variety were planted on May 1, 15 and 30, in three different levels of plant populations. The results obtained were summarized as follows: 1. The genetic variabilities of multi-ear and tillering habits were greater than environmental variabilities. 2. Total dry leaf weight of individual plant of MET line was also significantly higher than that of Suwon #19. 3. The mean number of tillers and ears bearing on the individual plant of MET line varied greatly with plant densities. The number of tillers and ears was on the average 2.9 and 7.0, respectively, when planted in 60cm. by 60cm. 4. The total dry matter and dried stem weight of the individual plant on MET line were comparable to those of Suwon #19. 5. The kernel weight from the individual plant of MET line was 5 to 40% less than that of Suwon #19, depending upon the plant densities. 6. The Kernel to stover ratio was higher for Suwon #19 than for the MET line. (41% to 35%). 7. The MET line had shown first tiller two weeks after planted on May 1. The second and third tillers appeared three to five days after the appearance of the first tiller. 8. The MET line was very specific in tillering habits. All the tillers were borne on the first few nodes of main stem below the soil surface. 9. The tillering habits of MET line were vigorous in the early part of the growing season, but less vigorous in the later part of the growing season. The number of efficient tillers bearing useable ears, was around two to three, when planted in 60cm. by 60cm. 10. The difference of plant height between main stem and first few tillers was around 10cm. 11. The ear size of MET line was around one-third of the major corn belt hybrids. The shape of ear of MET line was conical, with different diameter. 12. The kernel of the MET line was flinty with small soft starch patches on the endosperm part. 13. The 100 kernel weight was around 15gr., which is about one half of the major high yielding hybrids. 14. The ear height of MET line was comparatively higher than that of Suwon #19. 15. Significantly high and positive phenotypic correlation coefficients were obtained among major plant characters. 16. The growth rate of MET line was slower than that of Suwon #19. 17. MET line and Suwon #19 were both heavily infected with black streaked mosaic virus.

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Severe Outbreak of Rice Stripe Virus and Its Occurring Factors (벼줄무늬잎마름바이러스의 대 발생과 발생 요인)

  • Kim, Jeong-Soo;Lee, Gwan-Seok;Kim, Chang-Seok;Choi, Hong-Soo;Lee, Soo-Heon;Kim, Mi-Kyeong;Kwag, Hae-Ryun;Nam, Mun;Kim, Jeong-Sun;Noh, Tae-Hwan;Kang, Mi-Hyung;Cho, Jeom-Deog;Kim, Jin-Young;Kang, Hyo-Jung;Han, Jong-Woo;Kim, Byung-Ryun;Jeong, Sung-Soo;Kim, Ju-Hee;Kuo, Sug-Ju;Lee, Jung-Hwan;Kim, Tae-Sung
    • The Korean Journal of Pesticide Science
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    • v.15 no.4
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    • pp.545-572
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    • 2011
  • The genetic diagnosis methods by RT-PCR and Virion capture (VC)/RT-PCR against Rice stripe virus (RSV) were developed. Three diagnosis methods of seedling test, ELISA and RT-PCR were compared in virus detection sensitivity (VDS) for RSV. The VDS of ELISA for RSV viruliferous small brown plant hopper (SBPH) was higher with 40.5% than that of seedling test. The VDS of RT-PCR was higher with 21% than that of ELISA. The VDS of ELISA and VC/RT-PCR was same with 9.2% in average on the SBPH collected from fields at the areas of Gimpo, Pyungtaeg and Sihueng, Gyeonggi province in 2009. The specific primers of RSV for SBPH and rice plant were developed for the diagnosis by Real time PCR. The RQ value of Real time PCR for the viruliferous and non viruliferous SBPH was 1 for 50 heads of non viruliferous SBPH, 96.5 for 50 heads of viruliferous SBPH, 23.1 for 10 heads of viruliferous SBPH + 40 heads of non viruliferous SBPH, and 75.6 for 30 heads of viruliferous SBPH + 20 heads of non viruliferous SBPH. The RQ value was increased positively by the ratio of viruliferous SBPH. Full sequences of 4 genomes of RSV RNA1, RNA2, RNA3 and RNA4 were analysed for the 13 RSV isolates from rice plants collected from different areas. Genetic relationships among the RSV isolates of Korea, Japan and China were classified as China + Korea, and China + Korea + Japan by phylogenetic analysis for RSV RNA1 and RNA2. In case of RNA3 involved in pathogenicity, genetic relationship of RSV among the three countries was grouped into 3 as China, China + Korea, and Korea + Japan. According to the genetic relationships in RSV RNA4, RSV isolates were grouped into 4 as China, Korea, China + Korea + Japan, and Korea + Japan. Viruliferous insect rate (VIR) of RSV in average increased in each year from 2008 to 2010, and the rates were 4.3%, 6.1%, and 7.2%, respectively, at the 28 major rice production areas in 7 provinces including Gyeonggido. The highest VIR in each year was 11.3% of Gyeonggido in 2008, 20.1% of Jellanamdo in 2009 and 14.2% of Chungcheongbukdo in 2010. The highest VIR depending upon the investigated areas was 22.1% at Buan of Jellabukdo in 2008, 36% at Wando and Jindo of Jellanamdo in 2009, and 30.0% at Boeun of Chungcheongbukdo in 2010. Average population density (APD) of overwintered SBPH was 13.1 heads in 2008, 13.9 heads in 2009 and 5.6 heads in 2010. The highest APD was 39.1 and 60.4 heads at Buan of Jellabukdo in 2008 and 2009, respectively, and 14.0 heads at Pyungtaeg of Gyeonggido. The acreage of RSV occurred fields was 869 ha in the western and southern parts, mainly at Jindo and Wando areas, of Jellanamdo in 2008. In 2009, RSV occurred in the acreage of 21,541 ha covered whole country, especially, partial and whole plant death were occurred with infection rate of 55.2% at 3,025 plots in 53 Li, 39 Eup/Myun, 19 Si/Gun of Gyeonggido, Incheonsi, Chungcheongnamdo, Jeollabukdo and Jeollanamdo. Seasonal development of overwintered SBPH was investigated at Buan, Jeollabukdo, and Jindo, Jeollanamdo for 3 years from 2008. Most SBPH developed to the 3rd and 4th instar on the periods of May 20 to June 10, and they developed to the adult stage for the 1st generation on Mid and Late June. In 2009, all SBPH trapped by sky net trap were adult on May 31 to June 1 at Mid-western aeas of Taean, Seosan and Buan, and South-western areas of Sinan and Jindo. The population density of adult SBPH was 963 heads at Taean, 919 at Seocheon and 819 at Sinan area. The origin of these higher population of adult SBPH were verified from the population of non-overwintered SBPH but immigrant SBPH. From Mid May to Mid June in 2010, adult SBPH could not be counted as immigrant insects by sky net trap. The variation of RSV VIR was high with 2.1% to 9.5% for immigrant adult SBPH trapped by sky net trap at Hongsung of Chungcheongbukdo, Buan of Jeollabukdo and so forth in 2009. The highest VIR for the immigrant adult SBPH was 9.5% at Boryung of Chungcheongnamdo, followed by 7.9% at Hongsung of Chungcheongnamdo, 6.5% at Younggwang of Jeollanamdo, and 6.4% at Taean of Cheongcheongnamdo. The infection rate of RSV on rice plants induced by the immigrant adult SBPH cultivated near sky net trap after about 10 days from immigration on June 12 in 2009 was 84.6% at Taean, 65.4% at Buan and 92.9% at Jindo, and 81% in average through genetic diagnosis of RT-PCR. Barley known as a overwintering host plant of RSV had very low infection rate of 0.2% from 530 specimens collected at 10 areas covering whole country including Pyungtaeg of Gyeonggido. Twenty nine plant species were newly recorded as natural hosts of RSV. In winter annual plant species, 11 plants including Vulpia myuros showed RSV infection rate of 24.9%. The plant species in summer annual ecotype were 13 including Digitaria ciliaris with 44.9%, Echinochloa crusgalli var. echinata with 95.2% and Setaria faberi with 65.5% in infection rate of RSV. Five perennial plants including Miscanths sacchariflorus with infection rate of 33.3% were recorded as hosts of RSV. Rice cultivars, 8 susceptible cultivars including Donggin1 and 17 resistant ones including Samgwang, were screened in field conditions at 3 different areas of Buan, Iksan and Ginje in 2009. All the susceptible cultivars were showed typical symptom of mosaic and wilt. In 17 genetic resistant cultivar, 12 cultivars were susceptible, however, 5 cultivars were field-resistant plus genetic resistant to RSV as non symptom expression. When RSV was artificially inoculated at seedling stage to 4 cultivars known as genetic resistant and 3 cultivars known as genetic susceptible, the symptom expression in resistant cultivars was lower as 19.3% in average than that of 53.3% in susceptible ones. In comparison of symptom expression rate and viral infection rate using resistant Nampyung and susceptible Heugnam cultivars by artificial inoculation of RSV at seedling stage, the symptom expression of Heugnam was higher as 28% than 12% of Nampyung. However, virion infection of resistant Nampyung cultivar was higher as 12% reversely than 85% of susceptible Heugnam. Yield loss of rice was investigated by the artificial inoculation of RSV at the seedling stage of resistant cultivars of Nampyung and Onnuri, and susceptible cultivars of Donggin1 and Ungwang for 3 years from 2008. The average yield per plant was 7.8 g, 8.5 g and 13.8 g on rice plants inoculated at seedling stage, tillering stage and maximum tillering stage, respectively. The yield loss rate was increased by earlier infection of RSV with 51% at seedling stage, 46% at tillering stage and 13% at maximum tillering stage. In resistant rice cultivars, there was no statistically significant relation between infection time and yield loss. In natural fields on susceptible rice cultivar of Ungwang at Taean and Jindo areas in 2009, the yield loss rate was increased with same tendency to the infection hill rate having the corelation coefficient of 0.94 when the viral infection was over 23.4%.