Evolutionary relationship of alfalfa mosaic virus with cucumber mosaic virus and brome mosaic virus

The amino acid sequences of the non-structural protein (molecular weight 35,000; 3a protein) from three plant viruses — cucumber mosaic, brome mosaic and alfalfa mosaic have been systematically compared using the partial genomic sequences for these three viruses already available. The 3a protein of cucumber mosaic virus has an amino acid sequence homology of 33.7% with the corresponding protein of brome mosaic virus. A similar protein from alfalfa mosaic virus has a homology of 18.2% and 14.2% with the protein from brome mosaic virus and cucumber mosaic virus, respectively. These results suggest that the three plant viruses are evolutionarily related, although, the evolutionary distance between alfalfa mosaic virus and cucumber mosaic virus or brome mosaic virus is much larger than the corresponding distance between the latter two viruses.     

Cowpea Mosaic Virus-Encoded Protease Does Not Recognize Primary Translation Products of M RNAs from Other Comoviruses

The protease encoded by the large (B) RNA segment of cowpea mosaic virus was tested for its ability to recognize the in vitro translation products of the small (M) RNA segment from the comoviruses squash mosaic virus, red clover mottle virus, and cowpea severe mosaic virus (CPsMV, strains Dg and Ark), and from the nepovirus tomato black ring virus. Like M RNA from cowpea mosaic virus, the M RNAs from squash mosaic virus, red clover mottle virus, CPsMV-Dg, and CPsMV-Ark were all translated into two large polypeptides with apparent molecular weights which were different for each virus and even for the two CPsMV strains. Neither the in vitro products from squash mosaic virus, red clover mottle virus, and CPsMV M RNAs nor the in vitro product from tomato black ring virus RNA-2 were processed by the cowpea mosaic virus-encoded protease, indicating that the activity of this enzyme is highly specific.     

Purification,electron microscopy and serology of virus isolated fromEuonymus europaea

“Euonymus mosaic virus”, purified from cucumber cotyledons by the differential and density-gradient centrifugation, shows typical nucleoprotein absorption spectrum. Electron microscopy reveals isometric virus particles of about 37 nm diameter. No reaction of purified “Euonymus mosaic virus” was observed with antisera against a raspberry ringspot virus, tobacco ringspot virus, cherry leaf roll virus, strawberry latent ringspot virus, tomato ringspot virus, elm mosaic virus, arabis mosaic virus, tomato bushy stunt virus and watermelon mosaic virus.     

Circular dichroism and sedimentation studies on the reconstitution of tobacco mosaic virus

Reconstitution of tobacco mosaic virus from its constituents, the coat protein and RNA, was investigated by means of ultracentrifugation and circular dichroism measurement. Tobacco mosaic virus protein forms a 20S double-layer disc under conditions favorable for tobacco mosaic virus reconstitution. Dibromination of the tyrosine 139 residue of tobacco mosaic virus protein prevents formation of the 20S disc.Acidification of the tobacco mosaic virus protein solution causes 20S discs to polymerize into long helical rods. Changes in the CD spectra of tobacco mosaic virus protein in the near-ultraviolet region suggest that stacking of the aromatic sidechains of amino acid residues stabilizes the helical rod. The dibrominated tobacco mosaic virus protein also has the ability of rod elongation under acidic condition. CD studies reveal that assembly of tobacco mosaic virus particles from its constituents is stabilized by the stacking effect between the base residues of RNA and the aromatic residues of tobacco mosaic virus protein.Cucumber green mottle mosaic virus protein, which acts as a substituent for tobacco mosaic virus protein in tobacco mosaic virus reconstitution, was also investigated.     

THE DISTRIBUTION OF VIRUSES IN LEAVES AND THEIR INACTIVATION BY ULTRA-VIOLET IRRADIATION

The infectivity of sap expressed from the lower epidermis stripped from leaves systemically infected with potato virus Y , henbane mosaic virus or tobacco mosaic virus was compared with that of sap from the underlying mesophyll. Results suggested that the concentration of virus in each of the two tissues was about the same.
Ultra-violet irradiation of leaves infected with potato virus Y or henbane mosaic virus greatly reduced the infectivity of sap expressed from subepidermal tissues.     

杭州地区发生的玉米花叶病由甘蔗花叶病毒引起

从杭州地区呈现玉米矮花叶典型症状的玉米病组织中提纯得到大量线状病毒粒子,大多数长度为750?nm。病组织中含有大量风轮状内含体和板状集结体。病毒外壳蛋白为33.6 kD。病毒RNA13’端序列(1.8 kb)与甘蔗花叶病毒(SCMV)同源性最高,达71.5%～99.1%,与高梁花叶病毒(SrMV)同源性次之,为67.8%～68.5%,与玉米矮花叶病毒(MDMV)同源性最低,仅为38.4%～48.4%,从而初步认为此病害由SCMV引起。根据已发表的SCMV外壳蛋白氨基酸序列作亲缘性分析,表明SCMV可分为美国、南非、澳大利亚;德国和中国三大类。     

Nucleotide sequence of Chinese rape mosaic virus (oilseed rape mosaic virus), a crucifer tobamovirus infectious on Arabidopsis thaliana

The complete nucleotide sequence of Chinese rape mosaic virus has been determined. The virus is a member of the tobamovirus genus of plant virus and is able to infect Arabidopsis thaliana (L.) Heynh systemically. The analysis of the sequence shows a gene array that seems to be characteristic of crucifer tobamoviruses and which is slightly different from the one most frequently found in tobamoviruses. Based on gene organization and on comparisons of sequence homologies between members of the tobamoviruses, a clustering of crucifer tobamoviruses is proposed that groups the presently known crucifer tobamovirus into two viruses with two strains each. A name change of Chinese rape mosaic virus to oilseed rape mosaic virus is proposed.Abbreviations 2-ME 2-mercaptoethanol - EDTA ethylenediaminetetraacetic acid - SDS sodium dodecyl sulfate - UTR untranslated region - MP movement protein - CP capsid protein - CRMV Chinese rape mosaic virus - TVCV turnip vein clearing virus - PaMMV paprika mild mottle virus - PMMV-I pepper mild mottle virus (Italian isolate) - PMMV-S pepper mild mottle virus (Spanish isolate) - ToMV tomato mosaic virus - TMV tobacco mosaic virus - TMGMV tobacco mild green mosaic virus - ORSV odontoglossum ringspot virus - SHMV sunn hemp mosaic virus - CGMMV cucumber green mottle mosaic virus - ORMV oilseed rape mosaic virus     

Sequence analysis of a soil-borne wheat mosaic virus isolate from Italy shows that it is the same virus as European wheat mosaic virus and Soil-borne rye mosaic virus

The complete sequence of the two RNAs of a furovirus isolate from durum wheat in Italy was determined. Sequence comparisons and phylogenetic analysis were done to compare the Italian virus with Soil-borne wheat mosaic virus (SBWMV) from the USA and with furovirus sequences recently published as European wheat mosaic virus (EWMV), from wheat in France, and Soil-borne rye mosaic virus (SBRMV), from rye and wheat in Germany. Over the entire genome, the Italian isolate RNA1 and RNA2 had respectively 97.5% and 98.6% nucleotide identity with EWMV, 95.5% and 85.8% with SBRMV-G and 70.6% and 64.5% with SBWMV. The Italian isolate was therefore clearly distinct from SBWMV. The European isolates all appear to belong to the same virus and the name Soil-borne cereal mosaic virus may resolve earlier ambiguities.     

STUDIES ON DANDELION YELLOW MOSAIC AND OTHER VIRUS DISEASES OF LETTUCE

The symptoms caused by dandelion yellow mosaic virus on cultivated lettuce, Lactuca serriola and L. virosa , are described and compared with those caused by lettuce mosaic virus. Lettuce is much more susceptible than dandelion to the yellow mosaic virus; no infections of dandelion were obtained by mechanical inoculation and only three by aphides, whereas infection of lettuce is regularly obtained by aphides and by inoculation provided an abrasive is used. Myzus ornatus, M. ascalonicus and Aulacorthum solani transmitted dandelion yellow mosaic virus but not lettuce mosaic virus, whereas Myzus persicae transmitted the latter but not the former. Nasonovia ribicola , the common lettuce aphis, transmitted neither. Aphides became infective only after feeding periods of some hours on the diseased plants and ceased to be infective within an hour of the infective feeding. Their efficiency as vectors was not increased by a preliminary starving period, as happens with Myzus persicae and lettuce mosaic virus. Lettuce mosaic virus was found in most samples of commercial seed, which explains its prevalence; no evidence was found for the seed-transmission of dandelion mosaic virus and it is doubtful if it occurs, for infected lettuce are so severely affected that they rarely set seed.
Cucumber mosaic virus was isolated from naturally infected lettuce.     

马铃薯Y病毒组病毒高产量提取方法的建立

本文报道了高产量提取芜菁花叶病毒（ＴｕＭＶ）、莴苣花叶病毒（ＬＭＶ）、芋花叶病毒（ＤＭＶ）和大豆花叶病毒（ＳＭＶ）的提取方法。本方法通过使用高盐浓度的磷酸盐缓冲液以及在缓冲液中加入氯化镁和脲,并用ＴｒｉｔｏｎＸ－１００作为澄清剂,替代常规使用的氯仿和正丁醇,成功的提取到了大量病毒粒子,上述四种病毒提取的得率分别是ＴｕＭＶ为１７３．３ｍｇ／ｋｇ病叶,ＬＭＶ为９６ｍｇ／ｋｇ病叶,ＳＭＶ为１９９．２ｍｇ／ｋｇ病叶,ＤＭＶ为１７６．６ｍｇ／ｋｇ病叶。     

Identification of soybean mosaic, southern bean mosaic and tobacco ringspot viruses from soybean in the People's Republic of China

Samples of soybean plants with virus-like symptoms were collected from several locations in the People's Republic of China in 1981. These samples were used to prepare inocula for mechanical inoculation to soybean. Twenty-one virus cultures were obtained, the identities of which were determined by serology, symptomatology and host range. Sixteen cultures contained only soybean mosaic virus, four of which were more pathogenic than any previously studied; one culture contained only tobacco ringspot virus, another only southern bean mosaic virus, and three other cultures mixed infections of soybean mosaic and southern bean mosaic viruses. This is the first report of the occurrence of tobacco ringspot virus and southern bean mosaic virus in soybean in the People's Republic of China.     

Transgenic tobacco plants expressing a coat protein gene of tobacco mosaic virus are resistant to some other tobamoviruses

Transgenic tobacco plants expressing the coat protein (CP) gene of tobacco mosaic virus were tested for resistance against infection by five other tobamoviruses sharing 45-82% homology in CP amino acid sequence with the CP of tobacco mosaic virus. The transgenic plants (CP+) showed significant delays in systemic disease development after inoculation with tomato mosaic virus or tobacco mild green mosaic virus compared to the control (CP-) plants, but showed no resistance against infection by ribgrass mosaic virus. On a transgenic local lesion host, the CP+ plants showed greatly reduced numbers of necrotic lesions compared to the CP- plants after inoculation with tomato mosaic virus, pepper mild mottle virus, tobacco mild green mosaic virus, and Odontoglossum ringspot virus but not ribgrass mosaic virus. The implications of these results are discussed in relation to the possible mechanism(s) of CP-mediated protection.     

SAP-TRANSMISSIBLE MOSAIC DISEASES OF SOLANACEOUS CROPS IN TRINIDAD

Four sap-transmissible viruses were isolated from cultivated Solanaceae in Trinidad: (1) tobacco mosaic virus, from tobacco, tomato and sweet pepper; (2) cucumber mosaic virus, from tobacco and petunia; (3) 'pepper vein-banding virus', probably related to pepper mosaic viruses in Puerto Rico and Brazil, from peppers and tobacco; (4) 'egg-plant mosaic virus', possibly related to the tobacco ring-spot virus, from egg-plant and tomato. Pepper vein-banding virus causes leaf-crinkling and vein-banding in Physalis floridana , petunia, various Nicotiana spp. and most peppers; the Large Bell Hot pepper is killed; tomato and egg-plant are immune. Egg-plant mosaic virus produces mosaic, ring-spotting, or both, on different solanaceous species. It also gives local and systemic ring-spotting on Chenopodium hybridum and necrotic local lesions on the primary leaves of cowpea (var. Black-eye); cucumber is a symptomless carrier. Only cucumber mosaic virus was found naturally infecting non-solanaceous hosts, cucumber and certain common wild plants.
The thermal inactivation point of pepper vein-banding virus is 62° C, its dilution end-point 2×10^-5 and its longevity in vitro 6 day s at 23–30° C.; corresponding values for egg-plant mosaic virus are 78° C., 10^-6 and over 3 weeks. Aphisgossypii transmits cucumber mosaic and pepper vein-banding, but not egg-plant mosaic, of which Epitrix sp. is an occasional vector. Tobacco mosaic, as elsewhere, probably has no regular insect vectors in Trinidad.     

Identification of Peanut Green Mosaic Virus Strains in India*

During field surveys, three peanut green mosaic virus isolates differing in symptomatology on groundnut and a few other hosts were collected. Ultrathin sections of infected groundnut leaflets showed cytoplasmic inclusions with pin wheels and scrolls. In enzyme-linked immunosorbent assay they reacted strongly with antisera to peanut green mosaic and soybean mosaic virus antisera, and moderately with adzuki bean mosaic and peanut stripe virus antisera. All isolates also reacted positively with antisera to peanut eye spot, blackeye cowpea mosaic, pea seed-borne mosaic, potato virus Y and tobacco etch viruses, and did not react with antisera to peanut mottle, bean yellow mosaic, bean common mosaic, clover yellow vein and sugarcane mosaic viruses. SDS-PAGE analysis of purified virus preparations of the three isolates showed a single polypeptide with mol. wt. of 34,500 daltons. Based on these results, the three isolates are identified as biologically distinct strains of peanut green mosaic virus.     

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.     

THE DISTRIBUTION OF VIRUSES IN DIFFERENT LEAF TISSUES AND ITS INFLUENCE ON VIRUS TRANSMISSION BY APHIDS

Exposing both surfaces of leaves systemically infected with cabbage black ring spot virus (CBRSV) or henbane mosaic virus to ultra-violet radiation decreases the infectivity of expressed sap to about one-fifth. As irradiation probably inactivates virus mainly in the epidermis, which occupies about one-quarter the volume of the leaves, these viruses seem to occur at much higher concentrations in sap from the epidermis than in sap from other cells. By contrast, tobacco mosaic virus seems not to occur predominantly in the epidermis.
CBRSV and henbane mosaic virus are normally transmitted most frequently by previously fasted aphids that feed for only short periods on infected leaves, but aphids treated like this transmit rarely from leaves that have been exposed to ultraviolet radiation. Irradiation has relatively little effect on the proportion of aphids that transmit after long infection feedings. Fasting seems to increase transmission by increasing the probability that aphids will imbibe sap from the epidermis of leaves they newly colonize. With longer periods on infected leaves, the ability of fasted aphids to transmit probably decreases because they then feed from deeper cells and their stylets contain sap with less virus. Only virus contained in the stylets seems to be transmitted, not virus taken into the stomach. About half the transmissions of henbane mosaic virus by aphids that have colonized tobacco leaves for hours may be caused by insects that temporarily cease feeding on the phloem and newly penetrate the epidermis.
Irradiating infected leaves affected the transmission of sugar-beet mosaic virus in the same way as that of henbane mosaic virus, but had little effect on the transmission of beet yellows virus, whose vectors become more likely to transmit the longer they feed on infected plants.     

山东烟台小麦土传病毒病由小麦黄花叶病毒和土传小麦花叶病毒相关病毒复合侵染所致

在山东省烟台地区的小麦上发生一种由土壤中禾谷多粘菌Polymyxa graminis传播的病毒病,感病小麦植株表现矮化褪绿和花叶症状.我们于1997年4月从病区采集感病小麦植株,进行了病毒种类鉴定.直接电镜观察发现有二种病毒粒子,一种粒子呈棒状,占大多数,其长度约为300nm和150nm; 另一种粒子呈线状,数量较少,长度为500nm～700nm.免疫电镜结果表明,棒状病毒粒子仅与土传小麦花叶病毒(soil-borne wheat mosaic virus, SBWMV)抗血清反应,而不与小麦黄花叶病毒(wheat yellow mosaic virus,WYMV)抗血清和小麦梭条斑花叶病毒(wheat spindle streat mosaic virus,WSSMV)抗血清反应;反之,线状病毒仅与WYMV、WSSMV抗血清反应,而不与SBWMV抗血清反应.用WYMV和SBWMV两种抗血清同时进行修饰时,线状病毒粒子和棒状病毒粒子均发生反应.     

Studies on the stabilizing forces of simple RNA viruses: II. Stability,dissociation and reassembly of cucumber mosaic virus

The stability properties of cucumber mosaic virus were investigated in relation to those of two other, well-described, icosahedral RNA viruses of similar geometry; the cowpea chlorotic mottle virus and the turnip yellow mosaic virus. High concentrations of neutral salts caused the dissociation of cucumber mosaic virus into its constituent RNA and protein subunits irrespective of the pH of the solution. At low ionic strength the effect of pH on the infectivity and the sedimentation behavior of the virus was tested between pH 4.0 and 8.5. No effect was noticed in this range, but significant change became evident at pH 9.8 and was complete at pH 10.45. The products of this alkaline treatment were a mixture of slower sedimenting nucleoproteins. The RNA inside cucumber mosaic virus was accessible to pancreatic ribonuclease. There was little or no pH-dependence of the ribonuclease susceptibility. Under no circumstances were protein capsids of cucumber mosaic virus ever obtained, neither by degradation of the virion, reassembly of the protein subunits, nor directly from the infected plant. These stability properties of cucumber mosaic virus are strikingly different from those of cowpea chlorotic mottle virus and turnip yellow mosaic virus, as reported in the literature, and indicate the possession of only weak inter-protein subunit linkages, or their total absence.     

Recognition and differentiation of seven whitefly-transmitted geminiviruses from India, and their relationships to African cassava mosaic and Thailand mung bean yellow mosaic viruses

Particles resembling those of geminiviruses were found by immunosorbent electron microscopy in extracts of plants infected in India with bhendi yellow vein mosaic, croton yellow vein mosaic, dolichos yellow mosaic, horsegram yellow mosaic, Indian cassava mosaic and tomato leaf curl viruses. All these viruses were transmitted by Bemisia tabaci whiteflies, all reacted with at least one out of ten monoclonal antibodies to African cassava mosaic virus (ACMV), and all reacted with a probe for ACMV DNA-1, but scarcely or not at all with a full-length probe for ACMV DNA-2. Most of the viruses were distinguished by their host ranges when transmitted by whiteflies, and the rest could be distinguished by their pattern of reactions with the panel of monoclonal antibodies. Horsegram yellow mosaic virus was distinguished from Thailand mung bean yellow mosaic virus by its lack of sap transmissibility, ability to infect Arachis hypogaea, failure to react strongly with the probe for ACMV DNA-2 and its pattern of reactions with the monoclonal antibodies. Structures resembling a ‘string of pearls’, but not geminate particles, were found in leaf extracts containing malvastrum yellow vein mosaic virus. Such extracts reacted with two of the monoclonal antibodies, suggesting that this whitefly-transmitted virus too is a geminivirus. All seven viruses from India can therefore be considered whitefly-transmitted geminiviruses.     

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.