Su Kim

First Report of Sclerotium Rot on Cymbidium Orchids Caused by Sclerotium rolfsii in Korea

Sclerotium rot was found on Cymbidium orchids at Seosan-si, Chungcheongnam-do, Korea, in July, 2010. Symptoms occurred on low leaves, which turned yellowish, after which the entire plant wilted. Severely infected plants were blighted and eventually died. White mycelial mats and sclerotia appeared on pseudobulbs. Based on the mycological characteristics and pathogenicity, the causal fungus was identified as Sclerotium rolfsii. This is the first report of new Sclerotium rot on Cymbidium spp. caused by S. rolfsii in Korea.

Sclerotium blight of Neofinetia falcata Caused by Sclerotium rolfsii in Korea

The Sclerotium blight was found on Neofinetia falcata at Yong-in city, Gyenggi-do, Korea. The symptom occurred low leaves yellowish and wilt of a whole plant. Severely infected plants were blighted and dies eventually. White mycelial mats appeared on the surface of basal stem and bulbs and the sclerotia were formed on stems, roots, and sphagnum moss. The sclerotia were spherical in shape, 1~3 mm in size and white to brown in color. The optimum temperature for the growth and sclerotia formation was on PDA. On the pathogenicity test, the first symptom was appeared 5 days after inoculation and development to severe stem rot and blight. The causal fungus was identified as Sclerotium rolfsii and we suggested to call that the new Sclerotium blight on Neofinetia falcata caused by Sclerotium rolfsii in Korea.

Characterization of a Novel Cucumber mosaic virus Isolated from Petunia hybrida

Department of Horticulture and Landscape, Seoul Women’s University, Seoul 139-774, Korea(Received on April 9, 2012; Revised on May 16, 2012; Accepted on May 16, 2012)Petunia hybrida is commonly used in landscapes andinteriors for its attractive flower. Virus-like foliar symp-toms, including a mosaic with dark green islands sur-rounding the veins and chlorosis on the leaf margins,were observed on a petunia plant from Icheon, Gyeonggi-do, Korea. Cucumber mosaic virus (CMV) was identifiedin the symptomatic petunia by serological testing for thepresence of CMV coat protein (CP) with a direct anti-body-sandwich-enzyme-linked immunosorbent assay.An agent was mechanically transmitted to indicatorplant species including Chenopodium quinoa. Exami-nation of the inoculated plant leaves by RT-PCR analy-sis and electron microscopy revealed the presence ofspecifically amplified CP products and spherical virionsof approximately 28 nm in diameter, respectively, pro-viding confirmation of a CMV infection. Analysis of CPsequences showed that CMV petunia isolate (CMV-YJC) shared 82.5−100% amino acid sequence identitywith CPs of representative CMV strains. Phylogeneticanalysis of CPs supports that CMV-YJC is a member ofCMV subgroup IA (CMV-IA) and has biological pro-perties of CMV-IA on host species. To our knowledge,this is the first report of CMV from P. hybrida in Korea.Keywords : coat protein, Cucumber mosaic virus, petunia,RT-PCR, sequence analysis, symptomPetunia hybrida is a perennial plant, known as the “king ofparterre flowers”. Petunia hybrida is one of six members ofthe Solanaceae grown primarily as an ornamental plant,and the most economically important due to its horticulturalvalue (Sink, 1984). Petunia is a popular bedding plant, thethird most valuable after geranium and impatiens (Hamrick,1997) and it is also grown in pots, hanging baskets, andbalcony/window boxes (Lesemann, 1996). Petunia plantsare propagated by seeds in nature, but new species ofvegetatively propagated petunia have been recently culti-vated as garden ornamentals in the world (Dai and Bao,2004). Plant viruses are responsible for severe diseases inmany crops, ornamental plants, and various plants, result-ing in major economic losses (Hull, 2002). Virus symptomsusually vary from local discoloration to severe perturbationof growth and development, or even death of the plant. Inmost relationships between virus and susceptible host, theinduction of disease symptoms results from colonization ofplant virus in which the agent modifies the metabolism ofits host at many different levels. In turn, host plant showsvarious responses to virus, depending upon genetic back-grounds, development stage and surrounding environment(Hull, 2002). Several viruses have been reported as naturallyinfecting petunia plants (Bellardi et al., 1996; Mavric et al.,1996; Pirone, 1978), and many viruses capable of infectingpetunia plants have been identified using artificial inocu-lation methods since petunia plants are frequently used asindicator hosts for virus diagnostic assays (Brunt et al.,1996; Lane, 1992). The virus most often detected in petuniaplants is Tobacco mosaic virus (TMV) and other commonlydetected viruses are and Chrysanthemum virus B (CVB),Cucumber mosaic virus (CMV), Tobacco ringspot virus(TRSV), Tobacco streak virus (TSV), Tomato ringspotvirus (ToRSV), and Tomato spotted wilt virus (TSWV)(Brunt et al., 1996; Lawson and Hus, 1994; Sanchez-Cuevas and Nameth, 2002). Among viruses infectingPetunia hybrida, CMV is a prevalent plant pathogen allover the world and has one of the widest host ranges of anyplant virus, infecting over 885 plant species in 65 families(Palukaitis et al., 1992). CMV is multi-component singlestranded virus, with three positive-sense RNAs (RNA1,RNA2 and RNA3) and an additional subgenomic RNA(RNA4) derived from RNA3 (Habili and Francki, 1974;Peden and Symons, 1973). RNA2 codes for the 2a protein,

Sclerotium blight of Phalaenopsis Orchids Caused by Sclerotium rolfsii in Korea

The Sclerotium blight was found on Phalaenopsis spp. at Dong-du-cheon city, and Hwa-seong city, Gyenggido, Korea in September 2009. The symptom included yellowing on lower leaves and wilt of a whole plant. Severely infected plants were blighted and died eventually. White mycelial mats appeared on the surface of basal stem and bulbs and the sclerotia were formed on stems, roots, and sphagnum moss. The sclerotia were spherical, 1-3 mm and white to brown. The optimum temperature for the growth and sclerotia formation was on PDA. On the pathogenicity test, the first symptom appeared 5 days after inoculation and developed to severe stem rot and blight. On the basis of mycological characteristics and pathogenicity, the causal fungus was identified as Sclerotium rolfsii. This is the first report on the sclerotium blight on Phalaenopsis spp. caused by Sclerotium rolfsii in Korea.

Resistance Evaluation of Radish (Raphanus sativus L.) Inbred Lines against Turnip mosaic virus

무(Raphanus sativus) 는 아시아 및 지중해 연안이 원산지로 알려진 한해살이 또 는 두해살이 식물이다. 우리나라의 5대 채소 가운데 하나 이며 우리나라 전체 채소 생산량 대비 무는 10%–15%로, 배 추와 더불어 우리의 주요 부식인 김치, 단무지, 외식업체의 식재료로 사용되는 중요 작물 중 하나이다(Ku 등, 2006; Lee 등, 2008). 영양가치측면에서 무는 필수무기질들과 칼슘, 비 타민 등이 풍부하여, 특히 겨울철에 무청을 말린 재료를 활 용한 다양한 음식으로 섭취함으로써 한국인들에게는 중 요 무기영양 공급원 작물이다. 최근 많은 양의 화학비료를 사용하는 무의 연작재배지에서 각종 생리적 장해와 바이 러스병이 점차 증가하고 있다. 특히 무 및 배추 등에서 순무 모자이크바이러스(Turnip mosaic virus, TuMV)를 비롯한 5종 바이러스들이 보고되었으나(Choi와 Choi, 1992; Chung 등, 2015; Ham, 1995; Kim 등, 2012), 순무모자이크바이러스에 의 한 피해가 우리나라뿐만 아니라 세계적으로도 무 재배 지 역에서 가장 크며 지속적으로 발생하고 있다. 순무모자이크바이러스는 Potyviridae과(科, family) Potyvirus속(屬, genus)으로 분류되며, 전 세계적으로 넓게 퍼져 있 으며 경제적 피해를 지속적으로 끼치는 중요 바이러스 중 하나이다(Provvidenti, 1996). 순무모자이크바이러스는 주

Screening of Tomato Cultivars Resistant to Bacterial Canker by Seedling Test

Bacterial canker, caused by Clavibacter michiganensis subsp. michiganensis, is a very damaging disease to tomato (Lycopersicon esculentum) farm in Korea. It infects tomato, spreads through the xylem and causes bacterial wilt and canker. Selection of resistant cultivar is the best way to prevent or reduce the occurrence of the disease. Thirty-nine tomato cultivars, twenty-one cherry tomato cultivars and thirteen rootstock tomato cultivars were inoculated with Clavibacter michiganensis subsp. michiganensis, to evaluate tomato cultivarspecific resistance against bacterial canker. In the evaluation of 73 major commercial cultivars, `Sunmyung`, `Sweet`, `Akiko`, `Dadaki`, `Match`, `Magnet`, `Friend`, and `Greenpower` were found to have a high level of resistance to bacterial canker of tomatoes.