Occurrence and distribution of lettuce mosaic disease in Tehran province from Iran

Lettuce mosaic virus (LMV) Cucumber mosaic virus (CMV) and Tomato spotted wilt virus (TSWV) were identified in fields of Tehran province. In this study 452 leaf samples were collected from the fields throughout the Tehran province during 2002 and 2003. Distribution of Lettuce mosaic virus (LMV), Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV)and Arabis mosaic virus (ArMV) was determined with DAS-ELISA. Percentage of single Infection to LMV. CMV or TSWV was 20.58, 15.93 and 9.96% respectively. Also 15.28% of samples were co- infected with LMV+CMV, 8.19% with LMV+TSMV and 7.74% with CMV+TSWV. 4.65% of samples were Infected to all of these three viruses. LMV was found in 48.69%, CMV in 43.59% and TSWV in 30.54% of samples totally. Therefore LMV is major dominant agent of lettuce mosaic disease in Tehran province. This is the first report of occurrence of TSWV on lettuce in Iran and first report of CMV and LMV in Tehran province.     

First Report of Cucumber mosaic virus Infecting Chinese Mallow in China

The virus in naturally infected, stunted Chinese mallow plants and mosaic leaves was identified as Cucumber mosaic virus (CMV). Six symptomatic plants and one symptomless plant were collected in Chongqing, China. DAS‐ELISA suggested CMV was likely associated with the diseased Chinese mallow. Double‐stranded RNA was extracted from the samples, analysed by RT‐PCR, and the coding sequences of their coat proteins (CPs) were sequenced. The results further confirmed CMV was the pathogen causing Chinese mallow stunted, mosaic disease. The isolate was named CMV‐DXC. The full sequence of CMV‐DXC CP was determined, and it had the highest nucleotide identity (99.4%) of those of CMV‐lily, CMV‐WSJ and CMV‐Hnt, respectively. Phylogenetic analysis shows that CMV‐DXC belongs to CMV subgroup II. To our knowledge, this is the first report of CMV infecting Chinese mallow in China.     

Occurrence, distribution and relative incidence of mosaic viruses infecting field--grown squash in Tehran province, Iran

Squash (Cucurbita pepo) belongs to Cucurbitaceae family. Every year Cucurbitaceae are planted world wide. They are one of the most important economic crops. Cucurbitaceae are threatened by viruses. Many viruses damage the plants of this family. Since nine viruses have been reported on squash from Iran. In this survey, during 2002--2003, to determine the distribution of Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV), 466 samples were collected from squash field in Tehran province. Infected plants showing symptoms such as: mosaic, yellowing, deformation, shoestring of leaves and fruit deformation and yield reduction. Distribution of CMV, ZYMV and WMV were determined by DAS-ELISA. Thepercentage of ZYMV, WMV and CMV were 35.6, 26.1 and 25.1% respectively. Triple infection (CMV+ZYMV+WMV) were found in 6.4% of samples. ZYMV were found the most frequently the viruses. This is the first report of WMV on squash in Tehran province.     

Virus diseases of garden lupin in Great Britain

Two viruses occur widely in lupins in Britain. Alfalfa mosaic virus (AMV), of which two strains were isolated, was found mainly in named Russell varieties. Lupin mottle virus (LMV), a previously undescribed strain of the bean yellow mosaic virus (BYMV) common pea mosaic virus (CPMV) complex, was found more commonly in seedling lupins. Cucumber mosaic virus (CMV) was isolated once. The AMV strains were differentiated by their reaction in Phaseolus vulgaris; they were serologically closely related. Both AMV and LMV were aphid transmitted but not transmitted in lupin seed. LMV was distantly serologically related to both BYMV and CPMV. It cross-protected against BYMV but not against CPMV and it differed from both these viruses in some host reactions. The CMV isolate from lupins was similar to type CMV. It was transmitted both mechanically and by aphid, easily from cucumber to cucumber, but with difficulty from cucumber to lupin.     

Alfalfa mosaic and cucumber mosaic virus infection in chickpea and lentil: incidence and seed transmission

Samples collected in 1994 and 1995 from commercial crops of chickpeas and lentils growing in the agricultural region of south-west Western Australia were tested for infection with alfalfa mosaic (AMV) and cucumber mosaic (CMV) viruses, and for members of the family Potyviridae using enzyme-linked immunosorbent assay (ELISA). In 1994 no virus was detected in the 21 chickpea crops tested but in 1995, out of 42 crops, AMV was found in two and CMV in seven. With lentils, AMV and/or CMV was found in three out of 14 crops in 1994 and 4 out of 13 in 1995, both viruses being detected in two crops in each year. Similar tests on samples from chickpea and lentil crops and plots growing at experimental sites, revealed more frequent infection with both viruses. No potyvirus infection was found in chickpeas or lentils in agricultural areas either in commercial crops or at experimental sites. However, bean yellow mosaic virus (BYMV) was detected along with AMV and CMV in irrigated plots of chickpeas and lentils at a site in Perth. When samples of seed from infected crops or plots of chickpeas and lentils were germinated and leaves or roots of seedlings tested for virus infection by ELISA, AMV and CMV were found to be seed-borne in both while BYMV was seed-borne in lentils. The rates of transmission found through seed of chickpea to seedlings were 0.1–1% with AMV and 0.1–2% with CMV. Seed transmission rates with lentil were 0.1–5% for AMV, 0.1–1% for CMV and 0.8% for BYMV. Individual seed samples of lentil and chickpea sometimes contained both AMV and CMV. With both species, infection with AMV and CMV was sometimes found in commercial seed stocks or seed stocks from multiplication crops of advanced selections nearing release as new cultivars. Seed-borne virus infection has important practical implications, as virus sources can be re-introduced every year to chickpea and lentil crops or plots through sowing infected seed stocks leading to spread of infection by aphid vectors, losses in grain yield and further contamination of seed stocks.     

Further studies on seed transmission in the ecology of some aphid-transmitted viruses

A small proportion (1–4%) of the seeds of Stellaria media extracted from fallow soil from three widely separated areas contained cucumber mosaic virus (CMV). S. media seeds buried for 21 months produced 5 % infected seedlings. S. media plants from Britain, N. America and Australia were least severely affected by the CMV strain obtained from their country of origin and showed more severe reactions when infected with two alien strains. Several weed species were experimentally infected with lettuce mosaic, turnip mosaic and cauliflower mosaic viruses but, although virus was detected in the seeds of some species, it was not transmitted to any of their seedlings.     

The incidence and distribution of viruses infecting lettuce, cultivated Brassica and associated natural vegetation in Spain

A virus survey was conducted during the spring and autumn of 2001 and 2002 to determine the presence, prevalence and distribution in Spain of the viruses that are most commonly found infecting lettuce and Brassica worldwide. Crop plants showing virus symptoms from the principal lettuce and Brassica-growing regions of Spain, and some samples of the annual and perennial flora nearby, were tested by enzyme-linked immunosorbent assays using specific commercial antibodies against the following viruses: Alfalfa mosaic virus (AMV), Broad bean wilt virus 1 (BBWV-1), Beet western yellows virus (BWYV), Cauliflower mosaic virus (CaMV), Cucumber mosaic virus (CMV), Lettuce mosaic virus (LMV), Pea seed-borne mosaic virus (PSbMV), Turnip mosaic virus (TuMV) and Tomato spotted wilt virus (TSWV). Samples were also tested with a Potyvirus genus antibody. Virus incidence was much lower in spring than in autumn, especially in 2001. In spring 2002, CMV and LMV were the most prevalent viruses in lettuce, while CaMV was the most important virus present in Brassica crops grown in Navarra, followed by CMV and BWYV. In the autumn, the spectrum of viruses was different; potyviruses were widespread in lettuce grown in Madrid, but TSWV and BWYV were predominant in the Murcia region. The prevalent Potyvirus detected in lettuce fields was LMV, but none of the samples collected were positive for PSbMV or TuMV. In Brassica crops, TSWV was the most abundant in autumn-sown crops, especially in the Navarra region. All of the viruses present in lettuce and Brassica were also frequently detected in their associated natural vegetation at the same time, suggesting that they probably play an important role as virus reservoirs. Sonchus spp. were particularly common and were frequently infected with CMV, LMV and BWYV. Another common species, Chenopodium album, was often infected with TSWV and BWYV. Multiple infections were common, especially in non-crop plants, and the most common combination was BWYV and TSWV. The role of weeds in the epidemiology of viruses that infect lettuce and Brassica crops in Spain is discussed.     

侵染天南星科植物病毒的分子鉴定及其生态学研究

通过病毒粒子部分提纯和形态学观察,发现侵染我国南方天南星科植物的病毒主要有线状和球状两种形态．经病毒基因组序列分析确定线状病毒为芋花叶病毒(DsMV);经血清学反应和序列分析确定球状病毒为黄瓜花叶病毒(CMV)．CMV CP基因序列同源性分析的结果表明,侵染天南星科的CMV是相对独立的种内变异类型,归属于亚组L同时,CMV存在对天南星科植物的适应性变异．对采自我国海南、湖南、浙江、上海等地的126个天南星科植物样品进行RNA核酸斑点杂交检测,获得病毒检测结果。海南省样品DsMV的检出率为73．3％,CMV的检出率为46．7％;湖南省样品DsMV的检出率为100％,CMV的检出率为38.5％;浙江省样品DsMV的检出率为93．0％,CMV的检出率为7．0％;上海市样品DsMV的检出率为100％,尚没有检测到CMV,首次证实了自然条件下CMV作为天南星科植物主要病毒的存在,在我国南方地区,该病毒对天南星科植物的自然侵染受到气候、季节和寄主等生态因子的影响。DsMV则在天南星科植物上普遍存在。     

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.     

The isolation and identification of rhubarb viruses occurring in Britain

Virus-like symptoms were common in British crops of rhubarb. All plants tested of the three main varieties, ‘Timperley Early’, ‘Prince Albert’ and ‘Victoria’, were virus-infected. Turnip mosaic virus and a severe isolate of arabis mosaic virus (AMV) were obtained from ‘Timperley Early’; and ‘Prince Albert’ contained turnip mosaic virus, cherry leaf roll virus (CLRV), a mild isolate of AMV and, infrequently, cucumber mosaic virus (CMV). The main commercial variety ‘Victoria’ contained turnip mosaic virus, CLRV, a mild isolate of AMV and, infrequently, strawberry latent ringspot virus (SLRV). All the viruses were identified serologically. The rhubarb isolates did not differ markedly from other isolates of these viruses in herbaceous host reactions, properties in vitro or particle size and shape. A rhubarb isolate of CLRV was distinguished serologically from a cherry isolate of the virus. Turnip mosaic virus, CLRV and SLRV, were transmitted with difficulty, but AMV isolates were readily transmitted by mechanical inoculation. Turnip mosaic virus was also transmitted to rhubarb by Myzus persicae and Aphis fabae. CLRV was transmitted in 6–8% of the seed of infected ‘Prince Albert’ and ‘Victoria’ rhubarb and in 72% of the seed of infected Chenopodium amaranticolor. Mild isolates of AMV were also transmitted in 10–24% of the seed of infected ‘Prince Albert’ and ‘Victoria’ plants.     

Disease intensity of some tomato viroses in Serbia

In this paper we present the data on the disease intensity of the tomato plants grown in glass and plastic-houses, and in the open field. The infection was caused by the following viruses: Tomato mosaic virus (ToMV), Tobacco mosaic virus (TMV), Tomato spotted wilt virus (TSWV), Alfalfa mosaic virus (AMV), Potato virus X (PVX), Potato virus Y (PVY), Tomato black ring virus (TBRV), Tomato ringspot virus (ToRSV), Tomato aspermy virus (TAV), and Cucumber mosaic virus (CMV). These viruses represented most frequent tomato pathogens in Serbia. According to the obtained results, it could be concluded that 92.94% of the tested tomato plants grown in glass and plastic-houses, and 89.82% grown in the open field were infected by one of the above viruses. Most of the plant samples were infected by two or more viruses. The most frequent viruses — tomato pathogens in Serbia were ToMV, PVY and TMV.     

Association of cucumovirus and potyvirus with betelvine (Piper betle L.) as evidenced by ELISA and RT-PCR

An attempt was made to detect various viruses of Piper betle grown at Mahoba and Banthara in India. DAC-ELISA and RT-PCR tests were performed in leaf sap samples of betelvine for detection of a cucumovirus (Cucumber mosaic virus) and potyvirus (Bean yellow mosaic virus) using specific antibodies and universal primers of respective viruses. DAC-ELISA could detect only CMV. However, RT-PCR detected both cucumovirus and potyvirus infection in betelvine samples. Association of CMV with betelvine was observed for the first time in the present study.     

Expression of an extracellular ribonuclease gene increases resistance to Cucumber mosaic virus in tobacco

Background

The apoplast plays an important role in plant defense against pathogens. Some extracellular PR-4 proteins possess ribonuclease activity and may directly inhibit the growth of pathogenic fungi. It is likely that extracellular RNases can also protect plants against some viruses with RNA genomes. However, many plant RNases are multifunctional and the direct link between their ribonucleolytic activity and antiviral defense still needs to be clarified. In this study, we evaluated the resistance of Nicotiana tabacum plants expressing a non-plant single-strand-specific extracellular RNase against Cucumber mosaic virus.

Results

Severe mosaic symptoms and shrinkage were observed in the control non-transgenic plants 10 days after inoculation with Cucumber mosaic virus (CMV), whereas such disease symptoms were suppressed in the transgenic plants expressing the RNase gene. In a Western blot analysis, viral proliferation was observed in the uninoculated upper leaves of control plants, whereas virus levels were very low in those of transgenic plants. These results suggest that resistance against CMV was increased by the expression of the heterologous RNase gene.

Conclusion

We have previously shown that tobacco plants expressing heterologous RNases are characterized by high resistance to Tobacco mosaic virus. In this study, we demonstrated that elevated levels of extracellular RNase activity resulted in increased resistance to a virus with a different genome organization and life cycle. Thus, we conclude that the pathogen-induced expression of plant apoplastic RNases may increase non-specific resistance against viruses with RNA genomes.

     

国家种质库保存大豆和菜豆种质的种传病毒检测

以国家种质中期库提供的300份大豆、100份菜豆种质为材料,分别采用血清学和分子生物学方法,对种传病毒的种类进行了检测。结果表明:在大豆种质中检测出大豆花叶病毒(SMV)、黄瓜花叶病毒(CMV)、苜蓿花叶病毒(AMV)3种病毒,阳性检出率分别为25.33%(76份)、13.67%(41份)和4.67%(14份)。大豆种质中还存在大豆花叶病毒与黄瓜花叶病毒、大豆花叶病毒与苜蓿花叶病毒的复合侵染。在菜豆种质中检测出菜豆普通花叶病毒(BCMV)阳性材料92份,种质带毒率高达92%。这些信息将会对今后采取相关措施提高国家种质库保存的豆类种质的质量提供帮助。     

Genetic analysis of helper virus-specific selective amplification of cucumber mosaic virus satellite RNAs

Satellite RNAs (sat-RNAs) are small molecular parasites associated with a number of plant RNA viruses. The cucumber mosaic virus (CMV) sat-RNAs are ca. 335 nucleotides and have evolved to produce a large number of closely related sat-RNAs. Different cucumoviruses can act as helper viruses in the amplification of CMV sat-RNAs. We have found that different helper viruses show a preference for a particular sat-RNA in a mixed infection. In this study the specificity of WL47 sat-RNA amplification by LS-CMV and of D4 sat-RNA amplification by tomato aspermy virus in mixed infections was examined. Recombinant cDNA clones of D4 sat-RNA and WL47 sat-RNA were used to map the sat-RNA sequences responsible for the helper virus selection of a specific sat-RNA for amplification.Correspondence to: M.J. Roossinck     

Alarming increase in the incidence of Cucumber mosaic virus in cowpea (Vigna unguiculata (L.) Walp.) in northern Nigeria

Cowpea plays a key nutritional role in the diet of the Nigerian people. Viral diseases are a major limitation to cowpea production worldwide, and thus, constant viral surveillance is crucial for monitoring and management purposes. In this study, cowpea leaf samples from fields in three northern Nigeria states, Kano, Kaduna and Niger, were tested to determine the status of six common viruses previously reported in these cowpea-producing states following the release of virus-resistant varieties. Cowpea aphid-borne mosaic virus (CABMV), Blackeye cowpea mosaic virus (BICMV), Cowpea mottle virus, Southern bean mosaic virus and Cucumber mosaic virus (CMV) were detected. Cowpea yellow mosaic virus, which was previously reported in all three states, was not detected in any of the samples tested, while CMV that was previously regarded as unimportant to cowpea production in Nigeria had the highest incidence in all three states, and the overall highest incidence of 58.8%, while CABMV had the lowest incidence (7.5%). CMV was also present in seven of the ten mixed infection combinations detected. Dual infection of CMV and BICMV, which often results in cowpea stunt, the most devastating cowpea disease in the USA, was the most frequently detected mixed infection (28.1%) and was detected in all three states. This observed elevation in CMV infection in cowpea must be closely monitored and swiftly managed to avert possible devastating crop yield losses.     

Molecular mapping and characterization of a single dominant gene controlling CMV resistance in peppers (Capsicum annuum L.)

Cucumber mosaic virus (CMV) is one of the most destructive viruses in the Solanaceae family. Simple inheritance of CMV resistance in peppers has not previously been documented; all previous studies have reported that resistance to this virus is mediated by several partially dominant and recessive genes. In this study, we showed that the Capsicum annuum cultivar ‘Bukang’ contains a single dominant resistance gene against CMV_Korean and CMV_FNY strains. We named this resistance gene Cmr1 (Cucumber mosaic resistance 1). Analysis of the cellular localization of CMV using a CMV green fluorescent protein construct showed that in ‘Bukang,’ systemic movement of the virus from the epidermal cell layer to mesophyll cells is inhibited. Genetic mapping and FISH analysis revealed that the Cmr1 gene is located at the centromeric region of LG2, a position syntenic to the ToMV resistance locus (Tm-1) in tomatoes. Three SNP markers were developed by comparative genetic mapping: one intron-based marker using a pepper homolog of Tm-1, and two SNP markers using tomato and pepper BAC sequences mapped near Cmr1. We expect that the SNP markers developed in this study will be useful for developing CMV-resistant cultivars and for fine mapping the Cmr1 gene.