Defective Long-distance Transport of <Emphasis Type="Italic">Cucumber mosaic virus </Emphasis>in Radish Is Efficiently Complemented by <Emphasis Type="Italic">Turnip mosaic virus</Emphasis>

A strain of Cucumber mosaic virus (CMV-D8) systemically infects Japanese radish (Raphanus sativus), but the Y strain of CMV (CMV-Y) only infects the inoculated leaves. Both of these strains cause severe systemic mosaic on the plants after dual infection with Turnip mosaic virus (TuMV). Synergistic interactions on long-distance transport of CMV-Y and CMV-D8 with TuMV were analyzed using an immunobinding assay. Direct tissue blots probed with either anti-CMV-Y or anti-TuMV antiserum clearly showed that CMV-Y efficiently spread and accumulated in the tissues of noninoculated upper leaves and roots when co-inoculated with TuMV, and that long-distance movement of CMV-D8 was enhanced by the presence of TuMV. Received 16 September 1999/ Accepted in revised form 5 February 2000     

Characteristics for Practical Use of Attenuated Isolate UA-Fukushima of <Emphasis Type="Italic">Tomato mosaic virus</Emphasis>

L₁₁A-Fukushima (L₁₁A-F) derived from attenuated isolate LuA of Tomato mosaic virus (ToMV) has the highest ability to cross protect against virulent ToMV among LuA and its derivatives and is stably inherited. Growth, yield, fruit quality and symptom attenuation of inoculated tomato plants did not differ significantly between L₁₁A-F and L₁₁A. The infectivity of progeny viruses in tomato infected with LuA-F was less than 4% of that with virulent ToMV. From these results, L₁₁A-F appears to possess the properties necessary for practical use. To manage L₁₁A-F strictly, a PCR-based assay to detect trace contamination of virulent ToMV in L₁₁A-F preparations was established. Received 10 June 2002/ Accepted in revised form 30 October 2002     

<Emphasis Type="Italic">Turnip yellow mosaic virus</Emphasis> isolated from Chinese cabbage in Japan

A virus that caused a distinct yellow mosaic was isolated in Okayama, Japan from Chinese cabbage (Brassica rapa L., Pekinensis group). The virus, with spherical particles ca. 28 nm in diameter, was mechanically transmissible only to cruciferous species. From the host range, characteristic morphology of virus particles, serology and sequence analysis of coat protein gene, the causal virus was identified as Turnip yellow mosaic virus (TYMV). Seed transmission of TYMV at 0–2.2% in Chinese cabbage was confirmed. This report is the first of TYMV from Chinese cabbage and in Japan. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases as accessions AB358971 and AB358972.     

Movement of <Emphasis Type="Italic">Cucumber Mosaic Virus</Emphasis> Is Restricted at the Interface between Mesophyll and Phloem Pathway in <Emphasis Type="Italic">Cucumis figarei</Emphasis>

Viral movement in the leaf tissues of a resistant host, Cucumis figarei, inoculated with the pepo strain of Cucumber mosaic virus (CMV) and incubated at 24°C or 36°C was investigated by fluorescence in situ hybridization (FISH), leaf-press blotting, tissue printing and immunogold-silver staining techniques. Observation by FISH revealed that at 24°C most infection sites with CMV at 0.01 mg/ml or 0.1 mg/ml were limited to a single cell during the incubation period, that the number of infection sites increased from 24hpi (hours post inoculation) to 80 hpi in the leaves inoculated with CMV at 0.5 mg/ml, and that the size as well as the number of infection sites rapidly increased with time in the leaves inoculated with CMV at 2.0 mg/ml. These results suggested that one factor for the resistance of C. figarei at 24°C might be an inhibition of viral movement in and out of the infection sites. Leaf-press blotting and tissue blotting indicated that CMV remained in the infection sites at 24°C, whereas it spread from the inoculated leaves to other parts of the plants through vascular systems at 36°C. Immunogold-silver staining demonstrated that at 24°C CMV infected bundle sheath (BS) cells in minor veins, whereas at 36°C it invaded not only BS cells, but also phloem parenchyma (PP)/ companion cell (CC) or PP/intermediary cell (IC) complexes in minor veins in the regions with chlorotic symptoms. These results indicated that at 24°C CMV had difficulty in passing through the interface between BS and PP/CC or PP/ IC complexes and that viral entry from mesophyll to the phloem pathway was inhibited in the inoculated leaves. Received 26 August 1999/ Accepted in revised form 14 December 1999     

<Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> isolated from Amazon lily (<Emphasis Type="Italic">Eucharis grandiflora</Emphasis>)

Cucumber mosaic virus (CMV) was isolated from a mosaic diseased plant of Eucharis grandiflora. The virus caused mosaic symptoms on leaves and slight distortion of flower petals in E. grandiflora by either mechanical or aphid inoculation. The virus was identified as a strain of CMV subgroup I from its biological and serological characteristics.     

First report of blueberry red ringspot disease caused by <Emphasis Type="Italic">Blueberry</Emphasis><Emphasis Type="Italic">red</Emphasis><Emphasis Type="Italic">ringspot</Emphasis><Emphasis Type="Italic">virus</Emphasis> in Japan

Virus-like symptoms—red ringspots on stems and leaves, circular blotches or pale spots on fruit—were found on commercial highbush blueberry (Vaccinium corymbosum) cultivars Blueray, Weymouth, Duke and Sierra in Japan. In PCR testing, single DNA fragments were amplified from total nucleic acid samples of the diseased blueberry bushes using primers specific to Blueberry red ringspot virus (BRRV). Sequencing analysis of the amplified products revealed 95.7–97.7% nucleotide sequence identity with the BRRV genome. This paper is the first report of blueberry red ringspot disease caused by BRRV in Japan. The nucleotide sequence data reported in this paper are available in the GenBank/EMBL/DDBJ database as accessions AB469884 to AB469893 for BRRV isolates from Japan.     

Simultaneous detection of <Emphasis Type="Italic">Japanese yam mosaic virus</Emphasis> and <Emphasis Type="Italic">Yam mild mosaic virus</Emphasis> from yam leaves using a tube capture reverse transcription-polymerase chain reaction assay

To detect Japanese yam mosaic virus (JYMV) and Yam mild mosaic virus (YMMV) in yam plants in Japan, we developed a duplex RT-PCR assay consisting of a tube-capture procedure followed by one-step RT-PCR with two primer pairs. A 241-bp fragment of the coat protein region of JYMV and a 174-bp fragment of the nuclear inclusion protein b region of YMMV were amplified, thus identifying the two viruses from yam plants cultivated in Yamaguchi Prefecture in 2007. All water yam plants examined were infected with YMMV alone. All the Japanese yam and Chinese yam plants were infected with either JYMV alone or both JYMV and YMMV, suggesting that YMMV and JYMV are prevalent among field-grown yam plants.     

Phylogeny of Egyptian isolates of <Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> (CMV) and <Emphasis Type="Italic">Tomato mosaic virus</Emphasis> (ToMV) infecting <Emphasis Type="Italic">Solanum lycopersicum</Emphasis>

Four Cucumber mosaic virus (CMV) (CMV-HM 1–4) and nine Tomato mosaic virus (ToMV) (ToMV AH 1–9) isolates detected in tomato samples collected from different governorates in Egypt during 2014, were here characterized. According to the coat protein gene sequence and to the complete nucleotide sequence of total genomic RNA1, RNA2 and RNA3 of CMV-HM3 the new Egyptian isolates are related to members of the CMV subgroup IB. The nine ToMV Egyptian isolates were characterized by sequence analysis of the coat protein and the movement protein genes. All isolates were grouped within the same branch and showed high relatedness to all considered isolates (98–99%). Complete nucleotide sequence of total genomic RNA of ToMV AH4 isolate was obtained and its comparison showed a closer degree of relatedness to isolate 99–1 from the USA (99%). To our knowledge, this is the first report of CMV isolates from subgroup IB in Egypt and the first full length sequencing of an ToMV Egyptian isolate.     

Molecular characterisation of <Emphasis Type="Italic">Turnip mosaic virus</Emphasis> isolates from Brassicaceae weeds

Eight provinces of Iran were surveyed during 2003–2008 to find Brassicaceae reservoir weed hosts of Turnip mosaic virus (TuMV). A total of 532 weed samples were collected from plants with virus-like symptoms. The samples were tested for the presence of TuMV by enzyme-linked immunosorbent assay using specific antibodies. Among those tested, 340 samples (64%) were found to be infected with TuMV. Rapistrum rugosum, Sisymberium loeselii, S. irio and Hirschfeldia incana were identified as the Brassicaceae weed hosts of TuMV, and the former two plant species were found to be the most important weed hosts for the virus in Iran. The full-length sequences of the genomic RNAs of IRN TRa6 and IRN SS5 isolates from R. rugosum and S. loeselii were determined. No evidence of recombination was found in both isolates using different recombination-detecting programmes. Phylogenetic analyses of the weed isolates with representative isolates from the world showed that the IRN TRa6 and IRN SS5 isolates fell into an ancestral basal-Brassica group. This study shows for the first time the wide distribution and phylogenetic relationships of TuMV from weeds in the mid-Eurasia of Iran.     

The coat protein of <Emphasis Type="Italic">Tomato mosaic virus</Emphasis> L<Subscript>11</Subscript>Y is associated with virus-induced chlorosis on infected tobacco plants

The L₁₁Y strain of Tomato mosaic virus (ToMV) causes severe chlorosis on infected tobacco leaves. Sequencing analysis for the genome showed that L₁₁Y contained multiple nucleotide changes and that some led to amino acid substitutions, when compared with that of the common L strain of ToMV. The chimeric virus, which has the CP of L₁₁Y in the context of the L strain RNA genome, caused severe chlorosis on infected tobacco plants, suggesting that the CP of L₁₁Y containing three amino acid changes (E33S, A86T and E97K) was the determinant of the chlorosis. Two of these amino acid changes (A86T and E97K) were associated with the induction of chlorosis when present together in the CP. Severe destruction and deformation of chloroplasts and the formation of discrete dark-staining materials adjacent to chloroplasts were observed with electron microscopy in L₁₁Y-infected plants. Fewer virus particles accumulated in the cytoplasm of L₁₁Y-infected plant cells. The level of accumulation of CP subgenomic RNA and CP in the infected protoplasts was similar between L and L₁₁Y. Fewer virus particles accumulated in L₁₁Y-infected protoplasts, and many of them were shorter-than-full-length. The nucleotide sequence data reported is available in DDBJ/EMBL/GenBank databases as accession AB355139.     

Pymetrozine interferes with transmission of<Emphasis Type="Italic">Tomato yellow leaf curl virus</Emphasis> by the whitefly<Emphasis Type="Italic">Bemisia tabaci</Emphasis>

Pymetrozine, a novel compound belonging to the class pyridine-azomethines, is a feeding inhibitor labeled for use against plant pests in the order Hemiptera. Pymetrozine was evaluated for its ability to interfere with whitefly transmission of the begomovirusTomato yellow leaf curl virus (TYLCV). Pymetrozine was applied as Fulfill ^TM 50 WG at two rates (0.291 and 0.582 g formulationl ⁻¹) to tomato seedlings with four to six true leaves. Viruliferous whiteflies (three to five per plant) were added 1, 4, 7 and 11 d after a single application of pymetrozine, and transmission rates were determined 4 wk after the addition of whiteflies. Pymetrozine provided protection against transmission of TYLCV by viruliferous whiteflies for up to 1 wk after a single apliation. No phytotoxicity was observed on tomato transplants. These results indicate that pymetrozine could be an effective tool for tomato transplant producers to protect susceptible transplants from infection by begomoviruses, such as TYLCV. Pymetrozine might also work well as part of an integrated approach to begomovirus management in greenhouse tomato fruit production. http://www.phytoparasitica.org positing Oct. 20, 2003.     

Preservation of <Emphasis Type="Italic">Alfalfa mosaic virus</Emphasis> by freezing and freeze-drying and similarities to Cucumoviruses

Alfalfa mosaic virus (AMV) belongs to the genus Alfamovirus of the family Bromoviridae, for which the virions are stabilized by dominant protein–RNA interactions. The infectivity of purified AMV preparations stored frozen at −20°C decreased to 10–20% in 2 years. In addition, the virion peak profiles after sucrose density gradient centrifugation (SDGC) was reduced to a single, broad peak as a result of virus particle degradation, and the peaks for the extracted virion RNA decreased. However, additives such as 0.5% peptone or 2.5% sucrose were markedly protective such that infectivity and the SDGC profiles of the virus particles and virion RNA remained essentially unchanged after 5–8 years of freezing. Infectivity of the purified AMV decreased to c. 50%, and virus particles deteriorated immediately after freeze-drying. The addition of 1.0–7.5% sucrose suppressed alterations in infectivity, particle morphology and virion RNA after freeze-drying and other preservation processes. The characteristics of AMV preservation were similar to those reported in a previous study on cucumoviruses. Consequently, viruses belonging to the Bromoviridae may preserve well with sucrose in conjunction with freezing or freeze-drying.     

Evidence of <Emphasis Type="Italic">olive mild mosaic virus</Emphasis> transmission by <Emphasis Type="Italic">Olpidium brassicae</Emphasis>

Transmission of three strains of OMMV by an Olpidium sp. was evaluated and compared. The three strains were 1) an OMMV wild type (WT) recovered from olive trees, 2) an OMMV variant (L11) obtained after 15 serial passages of single local lesions induced in Chenopodium murale plants, and 3) a construct OMMV/OMMVL11 in which the coat protein (CP) gene replaced that of the wild type. A single-sporangial culture derived from Chinese cabbage (Brassica pekinensis) used as a bait plant grown in soil of an olive orchard, was identified as Olpidium brassicae based on the size and sequence of the generated amplicon in PCR specific tests. Each of the three virus strains was soil transmitted to cabbage roots in the absence of the fungus at similar rates of 30 to 40%. Separate plant inoculation by O. brassicae zoospores incubated with each viral strain resulted in enhanced transmission of OMMV, reaching 86% of infection whereas that of the other two strains remained practically unaffected at ca. 34%. Binding assays showed that the amount of virus bound to zoospores, estimated spectrophotometrically, was 7% in the case of OMMV, and practically nil in the case of the other two viral strains. Substitution of the coat protein (CP) gene of OMMV by that of the OMMV L11 strain, drastically reduced viral transmissibility in the presence of zoospores to the level of that observed in their absence. Our data shows that OMMV soil transmission is greatly enhanced by O. brassicae zoospores and that the viral CP plays a significant role in this process, most likely by facilitating virus binding and later entrance into the host plant roots.     

Detection and quantification of <Emphasis Type="Italic">Tomato mosaic virus</Emphasis> in irrigation waters

A quantitative RT real-time PCR method was developed for the detection and quantification of Tomato mosaic virus (ToMV) in irrigation waters. These have rarely been monitored for the presence of plant pathogenic viruses, mostly due to the lack of efficient and sensitive detection methods. The newly developed method presented here offers a novel approach in monitoring the health status of environmental waters. ToMV was reliably detected at as low as 12 viral particles per real-time PCR reaction, which corresponds to the initial concentration of approximately 4.2 × 10^?10 mg (6,300 viral particles) of ToMV per ml of sample. The sensitivity of the method was further improved by including the Convective Interaction Media^® (CIM) monolithic chromatographic columns for quick and efficient concentration of original water samples. Seven out of nine water sources from different locations in Slovenia tested positive for ToMV, after concentrating the sample. Four samples tested ToMV-positive without the concentrating procedure. The presence and integrity of infective ToMV particles in the original sample, as well as in the chromatographic fraction, was confirmed using different methods from test plants, DAS ELISA to electron microscopy and real-time PCR. In this study, we propose a unique and simple diagnostic scheme for rapid, efficient, and sensitive monitoring of irrigation waters that could also be adopted for other plant, human or animal viruses.     

Resistance of <Emphasis Type="Italic">Solanum</Emphasis> species to <Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> subgroup IA and its vector <Emphasis Type="Italic">Myzus persicae</Emphasis>

Sixty-nine tomato genotypes representing nine Solanum species were evaluated for resistance to Cucumber mosaic virus (CMV) subgroup IA and its aphid vector Myzus persicae. Resistance was assessed by visual scoring of symptoms in the field under natural conditions, and in the greenhouse by artificial inoculations through aphid M. persicae and mechanical transmissions in the year 2007 and 2009. Considerable variation in responses was observed among the evaluation methods used. Field evaluations were found liable to errors as different levels were observed for the same genotypes in the different years, however mechanical inoculation was found to be the most useful in identifying CMV subgroup IA resistance, in contrast aphid transmission was most useful in identifying insect transmission resistance. All genotypes observed as highly resistant to CMV subgroup IA in the field or through vector transmission became systemically infected through mechanical inoculations. Using mechanical inoculation, six genotypes (TMS-1 of S. lycopersicum, LA1963 and L06049 of S. chilense, LA1353, L06145 and L06223 of S. habrochaites) were found resistant and another six (L06188 and L06238 of S. neorickii, L06219 of S. habrochaites, L05763, L05776 and L06240 of S. pennellii) were found tolerant showing mild symptoms with severity index (SI) ranging 1-2 and with delayed disease development after a latent period (LP) of 18–30 days. However, these genotypes were found to be resistant to highly resistant in the field and through inoculation by M. persicae; and they also supported low population levels of M. persicae except TMS-1. Another nine genotypes (LA2184 of S. pimpinellifolium L., LA2727 of S. neorickii, LA0111, L06221, L06127 and L06231 of S. peruvianum L., LA1306, L06057 and L06208 of S. chmielewskii) showing a susceptible response after mechanical inoculation were highly resistant, resistant and tolerant after M. persicae transmission. The resistant genotypes, identified in the present study can be exploited in the breeding programmes aimed at developing tomato varieties resistant to CMV subgroup IA and broadening the genetic base of CMV-resistant germplasm. The differences observed between mechanical and aphid transmission suggests that one should consider both evaluation methods for tomato germplasm screening against CMV subgroup IA.     

Natural infection of <Emphasis Type="Italic">Nicandra physaloides</Emphasis> by <Emphasis Type="Italic">Tomato severe rugose virus</Emphasis> in Brazil

Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in São Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil.     

New potyvirus isolated from <Emphasis Type="Italic">Cryptotaenia japonica</Emphasis>

 A potyvirus, for which the name Japanese hornwort mosaic virus (JHMV) is proposed, was isolated from Japanese hornwort plants (Cryptotaenia japonica) with mosaic disease symptoms. The virus was used to inoculate mechanically 34 plants belonging to 33 species of 10 families. Of these species seven from two families were infected. Faint chlorotic spots appeared on the inoculated leaves of Chenopodium quinoa and C. amaranticolor, but no systemic infection occurred in these plants. JHMV systemically infected only Umbelliferae plants; they did not infect 26 other species in eight families. JHMV was transmitted in a nonpersistent manner by aphids (Myzus persicae). The virus was a flexuous rod-shaped particle about 750 nm in length. Sequencing the nucleotides in the 3′ terminal region of JHMV revealed that the coat protein contains 280 amino acids with a molecular mass of 32.2 kDa. The nucleotide sequence of the coat protein of JHMV had the highest similarity with that of Zantedeschia mosaic virus (83.3%) compared to those of other potyviruses (57.0%–64.9%). An antiserum against JHMV reacted strongly with JHMV and weakly with Potato virus Y. These results indicate that JHMV is a new potyvirus. Received: September 9, 2002 / Accepted: November 7, 2002 RID="*" ID="*" The nucleotide sequence determined in this work appears in the DDBJ/EMBL/GenBank nucleotide sequence databases with the accession number AB081518