Cucumber Green Mottle Mosaic Virus Research Articles

Serological diagnosis and host range studies of important viral diseases of a few cucurbitaceous crops in Maharashtra, India

Around 39 well characterised viruses affect cucurbits crops in developing countries and their viral diversity may be the consequence for genetic and ecological diversity of their hosts. Indeed, cucurbits are grown in variety of climatic, environmental and agricultural conditions, and this may provide more or less favourable conditions for the specific viruses or their hosts. The presence of various viral diseases caused by different viruses in Maharashtra was studied from the infected samples collected from cucurbits and melons during the survey conducted in 2009–2010 in different locations. The virus isolates collected from various cucurbitaceous crops were established and their host ranges were studied by sap transmission. The study revealed Cucumber Mosaic Virus (CMV), Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV) and Cucumber green mottle mosaic virus infections predominately found in Nashik region, and Watermelon bud necrosis virus (WBNV), CMV, ZYMV, WMV and Watermelon silver mottle virus (WSMoV) infections in Aurangabad and Paithan regions. In Sangamner region, the crop was mostly affected by WBNV, ZYMV and WSMoV, and CMV was found only in Sillod region. The protocols for performing sap transmission tests in assay hosts were standardised for ZYMV, CMV and WBNV. Using direct antigen-coating enzyme-linked immunosorbent assay, of all the plant parts, young leaves were found to have high concentration of virus and suitable for virus detection in screening programmes. CMV and ZYMV was found to have high concentration of virus and suitable for virus detection in screening programmes.

Molecular detection of Cucumber green mottle mosaic virus variants from cucurbits fields in Iran

Cucumber green mottle mosaic virus (CGMMV) is seed borne virus belonging to the genus Tobamovirus into family Virgaviridae, which transmit mechanically during agricultural practice, seed and through water. In this study, based on virus description cucurbits fields were observed to detect CGMMV. Therefore, biological purification was performed to recognise the type of symptoms incited by each isolates. Accordingly, local lesion host plants were inoculated with virus isolates. Following, the samples having CGMMV symptoms are selected to RNA extraction and molecular tests. Furthermore, to detect different strains of CGMMV, a pair of specific primers corresponding to full coat protein and a part of movement protein gene was applied to amplify a 523 bp fragment in reverse transcription polymerase chain reaction (RT-PCR). Eventually, an expected band with 523 bp length was revealed in nine isolates by RT-PCR. It is a first report of CGMMV from north-west of Iran by molecular methods.

One-step reverse transcription loop-mediated isothermal amplification for the rapid detection of cucumber green mottle mosaic virus

Cucumber green mottle mosaic virus (CGMMV) has caused serious damage to Cucurbitaceae crops worldwide. The virus is considered one of the most serious Cucurbitaceae quarantine causes in many countries. In this study, a highly efficient and practical one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed for the detection of CGMMV. The total RNA or crude RNA extracted from watermelon plants or seeds could be detected easily by this RT-LAMP assay. The RT-LAMP assay was conducted in isothermal (63°C) conditions within 1h. The amplified products of CGMMV could be detected as ladder-like bands using agarose gel electrophoresis or visualized in-tube under UV light with the addition of a fluorescent dye. The RT-LAMP amplification was specific to CGMMV, as no cross-reaction was observed with other viruses. The RT-LAMP assay was 100-fold more sensitive than that of reverse-transcription polymerase chain reaction (RT-PCR). This is the first report of the application of the RT-LAMP assay to detect CGMMV. The sensitive, specific and rapid RT-LAMP assay developed in this study can be applied widely in laboratories, the field and quarantine surveillance of CGMMV.

Viruses of cucurbits in Panama.

The main areas of field-grown cucurbit production in Panama were surveyed for the occurrence and distribution of viruses in the growing seasons of 2006 and 2008. Notably, in 2006 only Melon necrotic spot virus (MNSV) was detected, while Papaya ringspot virus (PRSV) was the most frequent in 2008 in terms of number of fields and samples analysed, followed by Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV) and MNSV. Cucumber mosaic virus (CMV), Squash mosaic virus (SqMV), Cucumber green mottle mosaic virus (CGMMV), Tomato spotted wilt virus (TSWV), Cucumber leaf spot virus (CLSV), Cucurbit yellow stunting disorder virus (CYSDV), Cucurbit aphid-borne yellows virus (CABYV), Beet pseudoyellows virus (BPYV), Beet yellows virus (BYV), and Cucumber vein yellowing virus (CVYV) were not detected . Single and double (PRSV+WMV; PRSV+ZYMV; ZYMV+MNSV) infections were detected in 60% and 40% of the samples tested, respectively. The occurrence and distribution of each virus varied according to the region and cucurbit species.

광간섭 단층촬영법을 이용한 우량 참외 종자 실시간 감별 시스템 개발

Abstract We developed a real-time screening system using optical coherence tomography (OCT) to distinguish the fruitful melon seedsefficiently. Cross-section images of melon seeds infected with Cucumber green mottle mosaic virus (CGMMV) showed an additionallayer that did not appear in normal seeds. Additional layer appeared under 100~300
um from the surface of the seed. OCT can visualizethe micro-structural and morphological changes of the internal seed structure. Real-time OCT seed screening system provided the real-time, non-destructive, cross-section image and quantitative information such as A-scan analysis of selected region in the cross-sectionimage. We can distinguish the viral infection seeds while monitoring the averaged A-scan analysis graph in real-time by considering thesecond peak value of the graph which refers to the layer that occurred owing to the virus. Real-time OCT seed screening system couldassist to distinguish the disease caused by CGMMV. Keywords : OCT (Optical Coherence Tomography), Real-time A-scan analysis, Plant imaging

First report of Cucumber green mottle mosaic virus (CGMMV) symptoms in watermelon used for the discrimination of non‐marketable fruits in Israeli commercial fields

The tobamovirus, Cucumber green mottle mosaic virus (CGMMV) causes severe disease of cucurbits worldwide. The typical symptoms in watermelon ( Citrullus lanatus ) including leaf mottling and mosaic have been reported in greenhouse-grown…

Detection of viruses in seeds of some vegetables by reverse transcriptase polymerase chain reaction (RT-PCR)

The present study was carried out to detect the presence of Alfalfa mosaic alfamovirus (AMV), cucumber mosaic cucumovirus (CMV), lettuce mosaic potyvirus (LMV), cucumber green mottle mosaic virus (CGMMV), tomato bushy stunt tombusvirus (TBSV), tobacco mosaic tobamovirus (TMV), tomato black ring nepovirus (TBRV) and tomato mosaic tobamovirus (ToMV) in seeds of pepper, tomato, cucumber and lettuce which are essential for human nutrition and seed production in Turkey. 50 seed samples for each vegetable obtained from various foundations and farmers were tested by reverse transcriptase polymerase chain reaction (RT-PCR) and double-antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) was conducted to compare the results. Besides, two total nucleic acid (TNA) extraction methods and a commercial RNA purification kit was compared to get high quality RNA for optimized RT-PCR. Purified total RNA extracts were used as template for cDNA synthesis, PCR products were analyzed by gel electrophoresis, and visualized by ethidium bromide staining. As a result of all, the optimum TNA extraction method was silica capture which is practical and easy to use for getting viral agents from tested vegetable seeds. RT-PCR was found rapid and sensitive in detecting viruses in seeds of vegetables when compared to DAS-ELISA. This study shows that RT-PCR can be successfully applied in certification programs and quarantine tests of vegetable seeds. Keywords : Seed, reverse transcriptase polymerase chain reaction (RT-PCR), total nucleic acid (TNA) extraction, optimization African Journal of Biotechnology Vol. 12(25), pp. 3891-3897

Pollen and seed transmission of Cucumber green mottle mosaic virus in cucumber

Cucumber green mottle mosaic virus (CGMMV) is transmitted mechanically in cucurbits, but whether it is transmitted via pollen to healthy plants and onto the subsequent generation of seedlings is unknown. Greenhouse experiments were conducted to investigate the importance of this route of infection. Cucumber seedlings at the 3‐true‐leaf stage were mechanically inoculated with CGMMV. At anthesis, scanning electron microscopy (SEM) and reverse transcription polymerase chain reaction (RT‐PCR) were used to verify the presence of CGMMV. Pollen was collected from the flowers of the infected plants and used to fertilize non‐inoculated plants. The rate of CGMMV transmission to the resulting fruits ranged from 17·1 to 51·2% compared with 33·3–100% for mechanically inoculated plants. Seeds were harvested from the cucumber fruits of both treatments and tested for the presence of CGMMV by RT‐PCR. The CGMMV‐positive seeds harvested from the two treatments were sown separately. The seed transmission rates for the inoculated and non‐inoculated plants were 16·7–100% and 12·8–76·7%, respectively. It was concluded that CGMMV can be transmitted both horizontally via cucumber pollen and vertically, to the next generation, in infected seeds. In addition the rate of seed transmission was much higher than previous reports. These findings have important implications for the disease management of CGMMV.

The Present Status of Breeding and Germplasm Collection for Resistance to Viral Diseases of Cucurbits in Japan

Cucumber (Cucumis sativus L.) and melon (C. melo L.) are globally important crop species in the family cucurbit. However, pests and disease, including various viral diseases, affect cucumber and melon production in Japan. Choosing a resistant cultivar is one of the most effective methods for disease control. Many sources of viral resistance have been identified in cucurbits, and various resistant commercial cultivars have been bred. This review describes the present status of cucurbit breeding and sources of resistance to the four major viruses in Japan. Melon yellow spot virus (MYSV) and Cucurbit chlorotic yellows virus (CCYV) are devastating insect-transmitted viruses that were first reported in Japan. MYSV-resistant cucumber and CCYV-resistant melon were selected from germplasm collections. The resistance of cucumber accession 27028930 to MYSV is temperature dependent and intermediate; melon isolate (MYSV-S) inoculation resulted in no systemic infection of resistant cucumber plants at low temperature (20°C). The melon accession JP 138332 exhibits high resistance to CCYV. These accessions are considered promising sources for breeding resistant cultivars. Cucumber green mottle mosaic virus (CGMMV) and Melon necrotic spot virus (MNSV) are soil-borne viruses. The Korean melon accession ‘Chang Bougi’ is resistant to the SH isolate of CGMMV. The resistance of ‘Chang Bougi’ is controlled by two independent complementary recessive genes (cgmmv-1 and cgmmv-2), whereas resistance to MNSV is controlled by a single recessive gene (nsv) in melon. The nsv gene was introduced into commercial cultivars, and these cultivars have shown high resistance to MNSV. There is an increasing demand for new cultivars with resistance to additional viruses. To satisfy this demand and solve problems related to cucurbit viruses, core collections of each cucurbit crop are required for the identification of resistant germplasm, and marker-assisted selection will allow us to breed new cultivars rapidly and accurately.

2007-2011 우리나라 농업현장 임상진단 요청 작물의 바이러스 감염 특성

National Institute of Horticultural and Herbal Science, Horticultural and Herbal Environmental Division,Suwon 441-707, Korea(Received on September 11, 2012; Revised on October 11, 2012; Accepted on October 12, 2012)The total number of requests and associated specimens for the diagnosis of virus infection were 573 and 2,992,respectively, on crops from agricultural places of farmers, Agricultural extension services and so forth for 5years from 2007. The total number of virus tests was 13,325. The number of species of viruses infected on thesubmitted crops was 21 in 2007, 15 in 2008, 23 in 2009, 21 in 2010 and 17 in 2011. The newly recorded viruseswere Tobacco leaf curl virus (TbLCV) in 2007, Tomato yellow leaf curl virus (TYLCV) in 2008, Impatiencenecrotic spot virus (INSV) and Radish mosaic virus (RaMV) in 2009, and Beet western yellows virus (BWYV) in2010. Forty virus species including Alfalfa mosaic virus were detected over 5 years. The ten most frequentlydetected virus species were Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV), Tomato leaf curlvirus (TYLCV), Cucumber green mottle mosaic virus (CGMMV), Broad bean wilt virus 2 (BBWV2), Zucchiniyellow mosaic virus (ZYMV), Melon necrotic spot virus (MNSV), Pepper mild mottle virus (PMMoV),Watermelon mosaic virus (WMV) and Pepper mottle virus (PepMoV). The types of crops submitted fromagricultural places were 51 in total and the ten most frequently submitted crops were red pepper, tomato,paprika, watermelon, melon, rice, cucumber, corn, radish and gourd. The total request rate for the top 10crops and top 20 crops was 81.6% and 94.2%, respectively. Eight pepper infecting virus species includedCMV, and the average infection rate was 24.6% for CMV, 18.9% for PMMoV and 14.7% for TSWV. Sevenkinds of double infection were detected in pepper including BBWV2+CMV at 14.7% on average, and fourtypes of triple infection including BBWV2+CMV+PepMoV at 0.9% on average. Six virus species detected ontomato including TYLCV, and the average infection rate was 50.6% for TYLCV, 14.5% for TSWV and10.9% for Tobacco leaf curl virus (TbLCV). The mixed infection of CMV+TSWV on tomato was 3.9% onaverage and of Tomato mosaic virus (ToMV)+TYLCV was 0.4% on average. Five viruses detected onwatermelon included MNSV and the average infection rate was 37.0% for MNSV, 20.4% for CGMMV,18.1% for ZYMV and 17.8% for WMV. The mixed infection rate on watermelon was CMV+MNSV andWMV+ZYMV having an average infection rate of 0.7% and 5.0%, respectively. The average infection rateson melon were 77.6% for MNSV, 5.6% for CMV and 3.3% for WMV. Mixed infections of CMV+MNSVoccurred on melon with an average infection rate of 13.5%. Keywords : BBWV2, BWVY, CGMMV, CMV, MNSV, Plant virus, TYLCV, ZYMV

Application of optical coherence tomography to detect Cucumber green mottle mosaic virus (CGMMV) infected cucumber seed

In this study, we distinguished Cucumber green mottle mosaic virus (CGMMV) infected seeds from healthy seeds using optical coherence tomography (OCT). Two dimensional OCT images and stereo micrographs revealed that the infected seeds had narrow gap between the seed coat and endosperm that were not present in the healthy seeds. Three dimensional OCT images confirmed that the narrow gaps were present in the inner structure of overall the infected seeds. A-scan analysis was also performed to calculate the distance from the seed coat to the endosperm. The results revealed a difference in the width of the gap of about 20 μm between healthy and infected cucumber seeds. Taken together, these results suggest that OCT could be applied as an effective non-destructive method for CGMMV infection of cucumber seeds.

Cucumber green mottle mosaic virus (CGMMV) can induce hair-like tissues on genus Cucumis seeds

Distinct morphological changes were observed on surface of Cucumber green mottle mosaic virus (CGMMV) infected genus Cucumis seeds. When the infected and healthy seeds were treated with ethanol series, unusual hair-like tissues were observed on surface of infected seeds. Morphology of these tissues was studied by stereo microscopy and field emission scanning electron microscopy. The hair-like tissues were observed on surface of seed coat of infected cucumber, musk melon and oriental melon and raised from the seed coats. Such tissues were not observed on seed coat of the same treated healthy cucumber and musk melon but such tissues were found as attached to seed coat of oriental melons. The width of hair-like tissues varied depend on species of genus Cucumis seeds, 2–2.5μm on musk melon and 9–10μm on oriental melon and cucumber seeds. The phenomenon was re-confirmed by RT-PCR and nested PCR assays that the seeds which had hair-like tissues on their seed coats were infected by CGMMV. Therefore, this study suggests that the hair-like tissues are a unique symptom as external morphological changes of genus Cucumis seeds induced by CGMMV.

Response of rhizobacterial communities in watermelon to infection with cucumber green mottle mosaic virus as revealed by cultivation-dependent RISA

We investigated the rhizobacterial densities and community structure in watermelon rhizosphere under the infection of cucumber green mottle mosaic virus (CGMMV) by artificial inoculation. Rhizobacterial densities and communities were analysed from healthy and infected plants under aerobic and anaerobic culture techniques. The highest total number of aerobic rhizobacteria was counted to be 2.7 × 108 colony forming units per gram (CFU · g−1) and anaerobic rhizobacteria was to be 3.2 × 106 CFU · g−1, in healthy and infected plants, respectively. Cultivation-dependent ribosomal intergenic spacer analysis (RISA) was employed for further analysis on the rhizobacterial community structure. By incorporating the relative abundance of amplicons, the per cent similarity was determined by the similarity coefficients based only upon the absence or presence of DNA bands. The cluster analysis of RISA showed that the community structure of aerobic rhizobacteria exhibited 60% similarity between healthy and infected plant. The highest community structure similarity (50% similarity) of anaerobic rhizobacteria occurred between before planting and infected plant.

Some Cultural Strategies to Help ManageBemisia Tabaci(Hemiptera: Aleyrodidae) and Whitefly-Transmitted Viruses in Vegetable Crops

The sweetpotato whitefly, Bemisia tabaci (Gennadius), is an important global pest of numerous crops as a result of its feeding and whitefly-transmitted plant viruses. To help develop a strategy to manage this pest and associated viruses in three vegetable crops in the Egyptian agricultural system, experiments on several cultural techniques were conducted. Cultural practices of mulching with white polyethylene, intercropping with maize (Zea mays L.), and crop rotation with maize resulted in reduced whitefly populations and reduced incidences of viruses in cucumber (Cucumis sativus L.), squash (Cucurbita pepo L.) and tomato (Solanum lycopersicum L.). However, no benefit in whitefly abundance and virus incidence was obtained from modifying the planting time by one month earlier than standard planting. There was a high correlation between whitefly abundance and virus incidence. Based on viral symptoms, up to 75 % infection was observed in untreated plots, while most of the treated plots had less than 40 % infection. The viruses affecting the crops were Cucumber vein yellowing virus in cucumber, Squash leaf curl virus in squash, and Tomato yellow leaf curl virus in tomato; they are common problems in Egypt. The first-mentioned virus is caused by an Ipomovirus in the family Potyviridae while the other two are Begomovirus in the family Geminiviridae. The cultural management strategies utilized in this study are viable tools to help manage B. tabaci and associated viruses in vegetable crops.

Erratum to: Molecular analysis of transgenic melon plants showing virus resistance conferred by direct repeat of movement gene of Cucumber green mottle mosaic virus

Erratum to: Molecular analysis of transgenic melon plants showing virus resistance conferred by direct repeat of movement gene of Cucumber green mottle mosaic virus

Molecular analysis of transgenic melon plants showing virus resistance conferred by direct repeat of movement gene of Cucumber green mottle mosaic virus

Cucumber green mottle mosaic virus (CGMMV) is a major limiting factor in the production of melon plants worldwide. For effective control of this virus using the transgenic approach, the direct repeat of the movement protein gene of CGMMV was used for transforming melon plants by Agrobacterium tumefaciens. PCR and Southern blot analyses of T₃ confirmed that they carried the transgene. Northern blot analysis with total RNA showed that transgene transcript RNA as well as siRNA was observed in all plants tested. Separate leaves or individual plants were inoculated with CGMMV and subjected to ELISA and RNA blot analysis using the coat protein gene probe of the virus. Compared to nontransgenic control, these plants were shown to have high virus resistance. Furthermore, cytosine of the transgene DNA in the plants was methylated. Thus, these results reveal that the transgenic lines were highly resistant to the virus through RNA silencing. Key message High virus resistance was obtained in transgenic melon plants with direct repeat of movement protein gene of Cucumber green mottle mosaic tobamovirus through RNA silencing.

Distribution of Viruses Infecting Cucurbit Crops and Isolation of Potential New Virus-Like Sequences from Weeds in Oklahoma.

Field surveys were conducted from 2008 to 2010 to detect and determine the incidence of viruses in the major cucurbit-growing areas of Oklahoma. In total, 1,049 symptomatic leaf samples (890 from cucurbits, 109 from weed species, and 50 from crop plants [agricultural crops]) were collected from 90 fields in four counties (Atoka, Blaine, Jefferson, and Tulsa) of Oklahoma. Samples were tested against seven viruses, including Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV), Melon necrotic spot virus (MNSV), Papaya ringspot virus-watermelon strain (PRSV-W, formerly known as Watermelon mosaic virus-1), Squash mosaic virus (SqMV), Watermelon mosaic virus-2 (WMV-2), and Zucchini yellow mosaic virus (ZYMV), using dot-immunobinding assay (DIBA). Results showed the highest incidence for PRSV (51%), followed by WMV-2 (14%) and ZYMV (10%) among the collected samples. SqMV, MNSV, and CMV were detected in 3.8, 3.3, and 1.1% of the samples, respectively. None of the samples collected during surveys reacted positively against the antiserum of CGMMV. Mixed virus infections were common involving two (5.18%) or three (4.61%) viruses in various combinations. New weed host species were found to be infected with PRSV when confirmed by both DIBA and reverse-transcription polymerase chain reaction (RT-PCR). Some weed species contained possible new viruses when analyzed by random RT-PCR, followed by cloning, sequencing, and BLAST analysis with sequences in GenBank.

Occurrence Of Viruses Infecting Watermelon, Other Cucurbits, and Weeds in the Parts of Southern United States

Field surveys were conducted to determine the distribution and frequency of viruses infecting watermelon and other cucurbits in the southern US in 2010 and 2011. Leaf samples were collected from 715 symptomatic plants from 10 states and were tested by dot-immunobinding assays or reverse transcriptionpolymerase chain reaction for 17 viruses that included Alfalfa mosaic virus (AMV), Bean pod mottle virus (BPMV), Cucurbit aphid born yellows virus (CABYV), Cucurbit yellow stunting disorder virus (CYSDV), Cucumber green mottle mosaic virus (CGMMV), Cucumber mosaic virus (CMV), Melon necrotic spot virus (MNSV), Papaya ringspot virus-W (PRSV-W), Squash leaf curl virus (SLCuV), Soybean mosaic virus (SMV), Squash mosaic virus (SqMV), Squash vein yellowing virus (SqVYV), Tobacco ringspot virus (TRSV), Watermelon mosaic virus (WMV), Watermelon silver mottle virus (WSMoV), Zucchini yellow mosaic virus (ZYMV), and Zucchini green mottle mosaic virus (ZGMMV). Thirteen out of 17 viruses were detected in this study. The distribution of detected viruses varied with the highest average frequency for WMV (30.6%), followed by PRSV-W (24.7%), ZYMV (13.9%), TRSV (5.7%), SqMV (3.5%), and MNSV (2.6%). The percent frequency of the remaining viruses was less than 2%. Seven viruses (AMV, BPMV, CMV, SqMV, TRSV, PRSV-W, and ZYMV) were also detected either from nearby agricultural crops or weeds species. Mixed infections were also recorded for some viruses with potyviruses being the most common. There is limited information on frequency and distribution of viruses that occur on watermelon and other cucurbits. These results indicate that potyviruses, particularly PRSV-W, WMV, and ZYMV, are frequently present in infected watermelon and other cucurbits in the southern US. Accepted for publication 30 July 2012. Published 24 August 2012.

성주지역 참외 바이러스병의 발생실태와 전염생태

참외 주산지인 성주에서 2008년부터 2010까지 약 2,000점의 시료를 수집하였으며, 참외에 발생하는 바이러스를 동정하고 병 발생생태를 구명하기 위하여 전자현미경 검경과 박과 작물에 발생하는 8종의 바이러스, CGMMV, CMV, KGMMV, MNSV, PRSV, SqMV, WMV2, ZYMV의 종 특이적인 프라이머를 이용한 RT-PCR 방법으로 바이러스 감염 여부를 분석하였다. 그 결과 CGMMV, WMV2, ZYMV의 발병을 확인하였으며, 이외 5종의 바이러스는 발생하지 않는 것으로 조사되었다. 본 조사에서 성주 참외에서 발생하는 주요 바이러스는 CGMMV와 WMV2임이 확인되었다. CGMMV는 생육초기부터 발생하며 생육 후기에는 거의 대부분의 참외가 감염이 이루어졌다. 반면에 WMV2는 참외보다 몇 달 늦은 6월쯤에 발생이 이루어졌다. 이들 바이러스들은 최초 감염이 이루어지고 나면 생육하면서 급격히 확산되어 매우 높은 감염율을 나타내었다. CGMMV는 지상부 식물체 모든 조직에서 검출되었으나, 호박을 대목으로 사용한 뿌리 조직에서는 검출되지 않았다. 시판종자 5품종을 진단한 결과 3품종에서 CGMMV가 검출되었다. 참외의 대목으로 사용하고 있는 시판용 호박에 CGMMV를 접종한 결과, 바이러스에 감염되지 않았다. CGMMV에 감염된 참외 식물체를 분쇄하여 혼합한 토양을 통한 CGMMV의 전염은 확인할 수 없었으며, 덩굴손과 줄기와의 접촉, 전지가위를 통해서 각각 48%, 30%의 전업률을 나타냈다. Throughout the years 2008 to 2010, we analyzed approximately two thousand oriental melon samples collected from Seongju, using electron microscopy and testing by RT-PCR using primers specific for eight cucurbit-infecting viruses. Data from RT-PCR indicated that Cucumber green mottle mosaic virus (CGMMV), Watermelon mosaic virus 2 (WMV2) and Zucchini yellow mosaic virus (ZYMV) were present and the other viruses were not detected. Among them, CGMMV and WMV2 were the most prevalent pathogens. CGMMV was thought to infect oriental melon from the early growing season, and reached nearly 100% in the later of growing period. Otherwise, WMV2 emerged from June, several months later compared to CGMMV. CGMMV was detected from all aerial parts of the oriental melon including seeds, but not from the roots of the grafted pumpkin rootstock. Seed of two out of five commercial varieties were shown to be CGMMV positive. Nine varieties of pumpkins used as rootstocks were not infected with CGMMV. When the seedlings of grafted oriental melon were transplanted into pots mixed with the oriental melon debris infected with CGMMV, they were not infected by CGMMV. Cutting of pruning shear and the contact of tendrils contributed 48% and 30% to the transmission of the virus, respectively.

Development of transgenic watermelon resistant to Cucumber mosaic virus and Watermelon mosaic virus by using a single chimeric transgene construct

Watermelon, an important fruit crop worldwide, is prone to attack by several viruses that often results in destructive yield loss. To develop a transgenic watermelon resistant to multiple virus infection, a single chimeric transgene comprising a silencer DNA from the partial N gene of Watermelon silver mottle virus (WSMoV) fused to the partial coat protein (CP) gene sequences of Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV) and Watermelon mosaic virus (WMV) was constructed and transformed into watermelon (cv. Feeling) via Agrobacterium-mediated transformation. Single or multiple transgene copies randomly inserted into various locations in the genome were confirmed by Southern blot analysis. Transgenic watermelon R(0) plants were individually challenged with CMV, CGMMV or WMV, or with a mixture of these three viruses for resistance evaluation. Two lines were identified to exhibit resistance to CMV, CGMMV, WMV individually, and a mixed inoculation of the three viruses. The R(1) progeny of the two resistant R(0) lines showed resistance to CMV and WMV, but not to CGMMV. Low level accumulation of transgene transcripts in resistant plants and small interfering (si) RNAs specific to CMV and WMV were readily detected in the resistant R(1) plants by northern blot analysis, indicating that the resistance was established via RNA-mediated post-transcriptional gene silencing (PTGS). Loss of the CGMMV CP-transgene fragment in R1 progeny might be the reason for the failure to resistant CGMMV infection, as shown by the absence of a hybridization signal and no detectable siRNA specific to CGMMV in Southern and northern blot analyses. In summary, this study demonstrated that fusion of different viral CP gene fragments in transgenic watermelon contributed to multiple virus resistance via PTGS. The construct and resistant watermelon lines developed in this study could be used in a watermelon breeding program for resistance to multiple viruses.