The Natural Occurrence of Turnip Mosaic Potyvirus in Allium ampeloprasum

An isolate of turnip mosaic potyvirus (TuMV) was obtained from Allium ampeloprasum grown in commercial greenhouses in Israel. Symptoms on infected plants include systemic chlorosis and yellow stripes, accompanied by growth reduction. Leaves were distorted, often showing necrotic flecking. The virus was readily transmitted mechanically, and in a non-persistent manner by aphids, among Allium, Chenopodium. Gomphrena and some Nicotiana spp. Purified preparations contained numerous filamentous particles similar to those observed in crude extracts of infected leaves. Particles from crude plant extracts had a normal length of 806 nm. Cells of infected plants contained cylindrical cytoplasmic inclusions with pinwheel, scrolls and laminated aggregates which indicated the presence of a potyvirus of Edwardson's subgroup III. and which resemble those of turnip mosaic virus (TuMV), The virus reacted strongly with antiserum to typical isolates of TuMV in immunoelectron microscopy and western blotting but not with antisera to several other potyviruses. Based on serological reactivity, electron microscopy, aphid transmission and cytopathology, the virus was identified as an isolate of TuMV.     

Resistance Against Pepper Severe Mosaic Potyvirus in Transgenic Tobacco Plants

The coat protein gene of the pepper severe mosaic poty-virus was introduced into tobacco plants. Several transgenic lines were assayed for virus resistance under greenhouse conditions. Line 232, showing higher levels of resistance than other transgenic plants, was studied in further detail. Upon challenge with PepSMV, R₂ descendants from this line were monitored for virus accumulation for a period of 45 days. Virus titre was lower in plants of the line 232 than in control plants throughout the experiment. At 14 days post-inoculation the transgenic plant line reached the maximum virus accumulation measured by ELISA. Those plants also showed a 1 week delay of virus accumulation by comparison with control plants. After reaching the peak at 14 days post-inoculation the virus titre in line 232 decreased with respect to control plants, until the end of the experiment. These results are compatible with the presence of an RNA-mediated resistance mechanism.     

Cytopathology of Mature Ovaries from Lettuce Plants Infected by Lettuce Mosaic Potyvirus

The location of lettuce mosaic potyvirus (LMV) in mature ovaries of lettuce plants ( Lactuca sativa ) was studied by conventional thin-section electron microscopy and immunogold cytochemistry. Flexuous filamentous particles and inclusion bodies characteristic of LMV infection were observed in the integumentary tapetum, integument and ovary wall of the mature ovary but not in the embryo sac.     

Calanthe Mild Mosaic Virus, a New Potyvirus Causing a Mild Mosaic Disease of Calanthe Orchid in Japan

Calanthe mild mosaic potyvirus (CalMMV), a previously undescribed virus found in several locations in Japan, causes mild leaf mosaic and flower colour breaking of Calanthe plants. CalMMV was mechanically transmitted only to Calanthe sp., Phalaenopsis sp. and Tetragonia expansa of 50 plant species tested and was transmitted by the aphid Myzus persicae in a nonpersistent manner. The virus has flexuotis particles about 764 nm long and induced the formation of intracellular cytoplasmic cylindrical inclusions. The virus particles contain a single poly-peptide of 32.0 kDa and a single RNA of mol. weight 3.1 × 10⁶. As determined by immuno-electron microscopy, CalMMV is distantly related to the Japanese isolate of dendrobium mosaic potyvirus (DeMV-J), but it showed no serological relationship to any of seven other potyviruses. The sequence of the 3'-terminal 1306 nucleo-tides of the viral genome was determined. The coat protein (CP) coding sequence is predicted to be 804 nucleotides in length, encoding a protein of 268 amino acids with a calculated mol. weight of 30 389. The 3' noncoding region is 169 nucleotides long and is followed by a polyadenylate tract. The amino acid sequence of the CP of CalMMV was 73% homologous to that of DeMV-J, but less than 66% to other potyviruses.     

马铃薯Y病毒组两病毒辅助成分的纯化及其传毒专化性的研究

马铃薯Ｙ病毒组两病毒辅助成分的纯化及其传毒专化性的研究吴云峰（植物病虫害生物学国家重点实验室,中国农业科学院植保所,北京１０００９４）魏宁生（西北农业大学植物保护系,陕西杨陵７１２１００）关键词马铃薯Ｙ病毒组,辅助成分,蚜虫传毒专化性自从１９７１年Ｋ...     

Identification and Characterization of a Potyvirus Isolated from Siratro Plants

The present work describes the identification and characterization of a potyvirus isolated from siratro (Macroptilium atropurpureum Urb.) in the north‐west region of the State of São Paulo, Brazil. The virus was transmitted by mechanical inoculation. Its host range was restricted mainly to members of the Fabaceae. A cDNA fragment of about 930 bp was amplified by RT/PCR, cloned and sequenced. The fragment, which included the coat protein gene, had amino acid identity percentages between 88 and 98% with isolates of Bean common mosaic virus (BCMV). Phylogenetic analysis grouped the siratro potyvirus and BCMV isolates in 99% of the replicates, including Azuki mosaic virus, Dendrobium mosaic virus, Blackeye cowpea mosaic virus and Peanut stripe virus, which have been classified as BCMV strains. This is the first citation on the presence of BCMV in siratro plants in Brazil.     

Serological and Biological Comparisons of Blackeye Cowpea Mosaic and Cowpea Aphid-borne Mosaic Potyvirus Isolates Seed-borne in Vigna unguiculata (L.) Walp. Germplasm

Serological and biological comparisons were made among 45 seed-borne isolates of blackeye cowpea mosaic (BICMV) and 54 seed-borne isolates of cowpea aphidborne mosaic (CAbMV) potyviruses derived from cowpea seedlots or young nursery-grown seedlings comprising 2112 germplasm accessions or pre-introduction seedlots of Vigna unguiculata. Isolates were identified by DAS-ELISA using polyclonal immunoglobulin G specific for these viruses. Twenty isolates of BICMV and 32 isolates of CAbMV were also compared by ACP-ELISA with selected monoclonal antibodies and by SDS-immunodiffusion. By all approaches, isolates of BICMV were clearly distinguished from CAbMV isolates. Isolate comparisons on selected cowpea genotypes (TVu-401, TVu-1582, TVu-2657, and TVu-3433) partitioned most isolates into two distinct groups. A few isolates seed-borne in Indian cv. Pusa Phalguni, however, were clearly BICMV by all serological tests, but behaved as CAbMV in definitive cowpea genotypes. Although BICMV is generally considered to be a 'new world virus', both BICMV and CAbMV occurred in V. unguiculata seedlots originating in 'old-world regions', including Afghanistan, Botswana, Nigeria, Senegal, and South Africa. Seedborne CAbMV was isolated from 6 of 155 tested US V. unguiculata Germplasm accessions originating, respectively, in Afghanistan (2), Botswana (2), India (1), and Pakistan (1).     

玉米矮花叶病毒提纯及特性的研究

改进病毒纯化方法,获得了较高纯度、较强侵染活性的提纯病毒制品。提纯病毒的产量为0.7—1.2mg/100g病叶,病毒粒体大小为720—750×14nm,SDS-聚丙烯酰胺凝胶电泳测得的外壳蛋白分子量为36000道尔顿,用提纯病毒免疫家兔得到较高特异性的抗血清,微量沉淀反应的效价为1/2048,间接ELISA法测出的感病叶汁液的最高稀释倍数为3200—6400倍。     

Characterization of Potyvirus Isolates from West African Yams (Dioscorea spp.)

In comparative studies on potyviruses from West African yams (Dioscorea spp.) the following isolates were used: Dioscorea greenbanding mosaic virus (DGMV) and a Nigerian yam virus (YV-N), both isolated from Dioscorea rotundata, and a beet mosaic virus isolate from D. alata (BtMV-Y) formerly designated Dioscorea alata ring mottle virus. Naturally infected D. alata containing very few particles of BtMV-Y, contained primarily particles of a second potyvirus (Dioscorea alata virus, DaV) which could not be transmitted but which was included in these studies wherever possible. The normal lengths of DGMV, YV-N, DaV, and BtMV-Y were 754, 772, 805, and 812 nm, respectively. All viruses induced cytplasmic inclusions of the pinwheel type and laminated aggregates. In addition, the nucleoli of BtMV-Y infected cells contained characteristic electron dense inclusions. The buoyant density of purified DGMV and BtMV-Y in CsCl was 1.336 g/cm³ and 1.321 g/cm³, respectively. The sedimention velocities (S_rel) of DGMV, YV-N, and BtMV-Y were 156, 158, and 162 Srespectively. In SDS-polyacrylamide gel electrophoresis the coat protein of purified DGMV and YV-N all migrated as a single band with an apparent molecular weight of 36 kd. Coat protein of purified DaV showed up to 5 bands with molecular weights of 36 to, 32 kd. Polypeptides of purified BtMV-Y had an estimated molecular weight of 35 kd but those from infected plant extracts had a molecular weight of 36 kd. DGMV, YV-N, and BtMV-Y particles contained a single nucleic acid with an apparent molecular weightof 3.2, 3.2, and 3.1 Md, respectively. Using λ-DNA digested with Hind III as a marker, the molecular weight of DGMV and BtMV-Y nucleic acid was calculated to be 3.6 Md ± 10%. The nucleic acid was determined to be single-stranded RNA by enzymatic digestion and by staining with acridine orange. In serological studies using immunoelectron microscopy (IEM), electro-blot immunoassay (EBIA), and enzyme-linked immunosorbent assay (ELISA), DGMV and YV-N were closely related. Strong serological reactions were also obtained in IEM and EBIA when DGMV and YV-N were tested with antiserum to yam mosaic virus (YMV). Antisera against DGMV, YV-N, and YMV also reacted strongly with DaV antigen. Serological reactions between these viruses and BtMV-Y were usually not found or were weak. A very close serological relationship could be detected between BtMV-Y and beet mosaic virus isolated from beet (BtMV); both isolates were also very similar in host range, symptomatology, and cytopathology.     

Purification and Characterization of Indian Cassava Mosaic Virus

The Indian cassava mosaic virus (ICMV) was transmitted by the whitefly Bemisia tabaci and sap inoculation. ICMV was purified from cassava and from systemically infected Nicotiana benthamiana leaves. Geminate particles of 16–18 × 30 nm in size were observed by electron microscopy. The particles contained a single major protein of an estimated molecular weight of 34,000. Specific antiserum trapped geminate particles from the extracts of infected cassava and N. benthamiana plants in ISEM test. The virus was detected in crude extracts of infected cassava, ceara rubber, TV. benthamiana and N. tabacum cv. Jayasri plants by ELISA. ICMV appeared serologically related to the gemini viruses of Acalypha yellow mosaic, bhendi yellow vein mosaic, Croton yellow vein mosaic, Dolichos yellow mosaic, horsegram yellow mosaic, Malvastrum yellow vein mosaic and tobacco leaf curl.     

Differentiation of Dasheen Mosaic Potyvirus Isolates Based on Variability in the Apparent Size of the Capsid Protein in Western Blots

The capsid protein (CP) sizes of seven dasheen mosaic virus (DsMV) isolates and one isolate of vanilla mosaic virus were estimated to be 38–47 kDa and 47 kDa, respectively, based on Western blot analyses using DsMV polyclonal antiserum. The CP sizes of 12 other potyviruses were estimated to be 31–36 kDa. Apparent CP sizes of the DsMV isolates extracted from their original hosts were 47 kDa ( Xanthosoma caracu ), 45 kDa ( Colocasia esculenta , Zantedeschia aethiopica ), and 38–46 kDa ( Caladium hortulanum ). Propagation in seedlings of Philodendron selloum did not affect the CP sizes of any of the individual DsMV isolates. The same characteristic CP sizes were also detected in Western blot analyses of these isolates, using polyclonal antisera of eight other potyviruses, or using Agdia Poty 1 monoclonal antiserum, and using three monoclonal antisera of papaya ringspot virus type W. The apparent CP size and pattern of apparent breakdown products as revealed by Western blots of extracts from infected aroids may be used in the characterization and differentiation of DsMV isolates.     

小麦黄花叶病毒和小麦梭条斑花叶病毒的生物学和分子生物学研究

线状土传小麦花叶病毒病在欧洲、亚洲和北美洲等地均有发生.这类病毒由根肿菌纲的禾谷多粘菌(Polymyxa graminis)传播,并归类于马铃薯Y病毒科(Potyviridae)的大麦黄花叶病毒属(Bymovirus).     

侵染香蕉的黄瓜花叶病毒株系的血清学特征

香蕉花叶病三类不同症状,即断续条纹类（BS）、连续条纹类（CS）和斑驳类（MM）在田间广泛存在,经过血清学、生物学、核酸斑点杂交和反转录聚合酶链反应,已确定它们都由黄瓜花叶病毒（Cucumberm。。i。virus,CMV）所弓愧f’］。这三类症状分离物在鉴别寄主、粒子形态、粒子电泳相对迁移率以及在西葫芦（CI;curbitafor）和烟草（Nicotianatabacumcv．HV38）上增殖和运转动力学的特征也表现不同［’］。这些不同可能揭示了香蕉三类分离物分属不同的株系。血清学是鉴定和研究CMV株系间亲缘关系的重要依据。大量文献【’,‘1报道…     

侵染番茄的番茄花叶病毒的研究

从种传番茄苗中获得一病毒分离物Ｔｏ－Ｓｌ,人工摩擦接种７科２４种植物,Ｔｏ～Ｓｌ能侵染４科１５种植物,在番茄上产生花叶,在白肋烟上为局部枯斑。Ｔｏ－Ｓｌ的钝化温度为８５～９０℃,稀释限点为１０￣（－６）～１０￣（－７）．体外保毒期在一个月以上。病毒粒体杆状,长度主要分布于２８１～３００ｎｍ之间,平均长度２８８ｎｍ。病毒衣壳蛋白亚基只有一条多肽链,分子量为２１ｋＤａ。ｄｓＲＮＡ分析测得其基因组长度为６．４ｋｂ。琼胎糖双扩散和胶内交叉吸附试验证明,Ｔｏ－Ｓｌ与ＴＭＶ有血清关系,但有一定的差异,病毒粒体电泳分析也表明Ｔｏ－Ｓｌ与ＴＭＶ粒体有差异。在交叉保护试验中,ＴＭＶ和Ｔｏ－Ｓｌ之间均无保护作用。根据以上试验结果Ｔｏ－Ｓｌ被鉴定为番茄花叶病毒。这是我国首次系统报道番茄上番茄花叶病毒的侵染。