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Soybean mosaic virus (SMV) is a prevalent pathogen that causes significant yield reduction in soybean production worldwide. SMV belongs to potyvirus and causes typical symptoms such as mild mosaic, mosaic and necrosis. SMV is seed-borne and also transmitted by aphid. Eleven SMV strains, G1 to G7, G5H, G6H, G7H, and G7a were reported in soybean varieties in Korea. A reverse transcription loop-mediated isothermal amplification (RT-LAMP) method allowed one-step detection of gene amplification by simple procedure and needed only a simple incubator for isothermal template. This RT-LAMP method allowed direct detection of RNA from virus-infected plants without thermal cycling and gel electrophoresis. In this study, we designed RT-LAMP primers named SML-F3/B3/FIP/BIP from coat protein gene sequence of SMV. After the reaction of RT-LAMP, products were identified by electrophoresis and with the detective fluorescent dye, SYBR Green I under daylight and UV light. Optimal reaction condition was at 58°C for 60 min and the primers of RT-LAMP showed the specificity for nine SMV strains tested in this study.

Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Korea(Received on February 23, 2012; Revised on August 9, 2012; Accepted on August 10, 2012)In July, 2009, proso millet (Panicum miliaceum), which showing the bacterial brown stripes on leaf sheaths,was collected in Miryang in Korea. Symptoms were systemic brown necrotic stripe lesions on the leaf sheathsand stems, and these symptoms were found in the entire field. The causal agent isolated from symptomaticplants was identified as an Acidovorax avenae subsp. avenae, based on its biochemical and physiologicalcharacteristics and also confirmed by the Biolog data and 16S rRNA gene sequence analysis. Also it causedhypersensitive response (HR) when it was inoculated onto the tobacco and tomato. It caused similarsymptoms when inoculated onto proso millet. This is the first report of A. avenae subsp. avenae, the causalagent of bacterial brown stripe of the proso millet in Korea. Keywords : Acidovorax avenae, Bacterial stripe, Panicum miliaceum기장(Panicum miliaceum L.)은 아프리카, 아시아, 남미에서 널리 이용되는 식량작물로 이들 지역의 단백질 공급에 기여하고 있다(Park 등, 2009). 또한 비타민, 무기질및 식이섬유 등의 기능성 성분의 함량이 높고 다양한 생리활성 물질이 많이 함유되어 있어 건강을 유지시키는 보조식량으로서의 역할이 중요시되고 있다(Ko 등, 2011). Acidovorax avenae subsp. avenae는 1909년 미국 오하이오 지역에서 귀리의 잎마름을 일으키는 식물병원세균으로 Manns(1909)에 의해 처음 보고된 후 벼 세균성줄무늬병(Goto, 1964; Kadota, 1996; Shakya 등, 1985), 옥수수의 세균성 줄기부패병(Rosen, 1926; Summer와 Schaad,1977), 조의 갈색줄무늬병(Rosen, 1926), 사탕수수와 기장의 붉은줄무늬병(Martin과 Wismer, 1989)을 일으키는 것으로 보고되었다. 국내에서는 벼 세균성줄무늬병(Shakya,1980)과 옥수수 줄기썩음병(Lee, 1991)이 보고되어 있으나, 기장에서는 아직 보고된 바 없다.본 연구는 국내에서 기장에 새롭게 발생한 세균성줄무늬병의 병징 및 병원세균의 균학적 특성을 보고하고자 한다.

In 2005, a survey was conducted to identify virus diseases on victory onion, Allium victorialis var. platyphyllum grown in Ulleung island located in the East Sea. A total of 61 samples were collected from victory onion in the neighborhood of Seonginbong. The identification of viruses from the samples were carried out by electron microscopy and RT-PCR using primers species specific to GCLV, LYSV, SLV, OYDV and genus specific to Allexivirus, respectively. From sixty-one samples, filamentous rod particles (600-900 nm) were detected from four victory onion samples in EM, three samples containing SLV and one sample containing both SLV and Allexivirus in RT-PCR analysis, respectively. Victory onions naturally infected by the viruses were asymptomatic apparently. The viruses detected by RT-PCR were further characterized by the nucleotide sequence analysis of the coat protein region. Three isolates of SLV showed approximately 99% identities in the nucleotide and amino acid sequences, suggesting that they were likely to be the same strain. On the other hand, they showed approximately 75.7~83.7% identities in the nucleotide and 89.2~97.0% in amino acid sequences compared with the previously reported SLV isolates in Allium. The CP gene of the Allexivirus showed approximately 99.2% nucleotide identities and 98.8% amino acid identities with Garlic virus A. However, there was relatively low homology ranging from 60.6% to 81.5% compared with other Allexiviruses (GarV-C, GarV-E, GarV-X, GMbMV, and Shal-X). These data suggested that two viruses, SLV and GarV-A identified from victory onion, are named SLV-Ulleungdo and GarV-A-Ulleungdo, respectively. This is the first report of viruses infecting victory onion.

During the period from 1999 to 2008, we surveyed the major diseases incidence of rice in Korea. Leaf blast showed 0.85% of the diseased leaf area in 2000 and then consistently decreased to 0.02% by 2008. However, panicle blast irregularly appeared by the years depending on weather conditions for disease development from heading to milk stage of rice. Diseased lesion height of sheath blight had the lowest (10.1%) incidence in 2001 and the highest (21.4%) incidence in 2007. A negative corelation ($r

This study was conducted to decide disease incidence level of rice leaf blast required for reasonable fungicide application in paddy field. We induced the disease development by inoculating rice blast pathogens on rice seedlings (Jinmibyeo) in the greenhouse and transplanting the infected seedlings in the field two weeks after rice plants were transplanted. We scored the disease incidence, grouped and marked according to degree of percentage of diseased leaf area at maximum stage of disease development. The percent diseased leaf area (PDLA) had negative correlations with panicle number per hill, ripened grain (%), and total yield; their correlation coefficients (r), , and , respectively. However, it had positive correlations with spikelets per panicle and thousand grain weight; their correlation coefficients (r), and , respectively. Gain threshold (GT) calculated based on control cost and market price was estimated to be 8.35. Economic injury level (EIL) obtained based on GT and coefficient of damage of regression equation between disease incidence and the different yield components; panicle number per hill, spikelets per panical, ripened grain(%), thousand grain weight and yield were 41.8, 9.7, 19.1, 291.1 and 3.4%, respectively. Economic threshold (ET) for yield was 2.7% () on PDLA. These results suggest that application of fungicide is necessary when two under leaves are almost covered with lesions or contained more than twenty large lesions under leaves at maximum tillering stage.

In year 2003, a soybean(Glycine max) sample showing severe dwarfing symptom was collected from a farmers` field in Cheongsong in Korea. The results from the diagnosis of the sample by RT-PCR revealed that it was infected by Soybean dwarf virus(SbDV), SbDV-L81. This study could be the first report of the occurrence of the virus in Korea. To further characterize the virus, the partial nucleotide sequence of the genomic RNA of SbDV-L81 was determined by RT-PCR using species-specific primers. The sequences were analyzed and subsequently compared to previously characterized strains of SbDV based on the pattern of symptom expression and vector specificities. The intergenic region between ORF 2 and 3 and the coding regions of ORF 2, 3 and 4 were relatively similar to those of dwarfing strains(SbDV-DS and DP) rather than those of yellowing strains(SbDV-YS and YP). Likewise, the result from the analysis of 5`-half of the coding region of ORF5 indicated that SbDV-L81 was closely related to strains(SbDV-YP and DP) transmitted by Acyrthosiphon pisum. These data from the natural symptom and the comparisons of five regions of nucleotide sequences of SbDV suggested that SbDV-L81 might be closely related SbDV-DP.