Comparison of the nucleotide and amino acid sequences of parental and attenuated isolates of Zucchini yellow mosaic virus

To identify possible sites of viral attenuation, the complete nucleotide sequences of two isolates of Zucchini yellow mosaic virus (ZYMV) were determined; a severe isolate Z5-1 and an attenuated isolate from Z5-1 (designated ZYMV-2002). The viral genome of both isolates consisted of 9593 nucleotides in size and contained an open reading frame encoding a single polyprotein of 3080 amino acids. Comparison of the nucleotide sequences for Z5-1 and ZYMV-2002 revealed 14 nucleotide mutations, resulting in seven amino acid substitutions with four in the HC-Pro region, two in the CI region, and one in the NIb region. These results provide a genetic basis for future manipulation of the ZYMV reverse genetics system. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession numbers AB188115 and AB188116     

Analysis of natural populations and possible natural reassortment of Cucumber mosaic virus

Plants naturally infected with Cucumber mosaic virus (CMV) were collected and analyzed by electrophoresis of the replicative form of dsRNA and by Northern blot hybridization using CMV RNA-specific probes. Some of the CMV-infected plants, especially winter crops, contained two kinds of RNA 1 segments or RNA 2 segments (or both), suggesting that mixed infections of CMV occurred naturally. Single-aphid-transmitted isolates (SATIs) from the field isolate containing two RNA 1 segments were grouped into three types by the electrophoretic mobility of RNA 1 (i.e., those containing one slow segment, those containing one fast segment, and those containing both). Furthermore, SATIs and single-lesion isolates, generated from the plants inoculated with a mixture of two CMV isolates that could be differentiated by their electrophoretic dsRNA profiles, were analyzed by dsRNA, indicating that nonparental progenies were observed. These results suggested that genetic reassortment of CMV RNA may occur in nature and that this is an important mechanism in CMV evolution.     

Cucumber mosaic virus isolated from Aconitum spp. in Japan

Viruses were isolated from leaves of plants of Aconitum species with symptoms such as mottling and yellowing in Hokkaido and Gunma prefectures in Japan. These viruses were identified as Cucumber mosaic virus (subgroup II) based on particle morphology, host range, aphid transmission, and serology.     

河南省主要推广品种对小麦黄花叶病毒抗性的评价

为了评价河南省主要推广品种对小麦黄花叶病毒(Wheat yellow mosaic virus, WYMV)的抗性,于2006—2010年在河南省西平县病圃进行了田间抗性鉴定试验和室内间接ELISA检测,并分析了病害严重程度对产量的影响。结果表明,在供试的62个品种中,仅有新麦208表现为免疫;豫麦70-36、泛麦5号、阜麦936、山东95519、豫麦70、高优503、豫麦9676、郑麦366和陕麦229等9个品种表现为抗病,占供试品种的14.5%;濮优938、兰考矮早8、新原958、花培2号、温优1号、豫麦18、郑麦9023、豫麦47、豫农201、偃展4110、豫麦36、百农878和豫麦49-198等13个品种表现为中抗,占供试品种的21.0%;另外39个品种表现为感病,占供试品种的62.9%。对48个品种进行了产量与病害严重度分析,发现随着病害的严重度增加,小麦的穗数、千粒重以及产量都有明显下降,严重度为1级时,平均减产9.6%;严重度达到2级和3级时,平均减产分别为30.3%和33.5%。     

Shoot meristem tissue of tobacco inoculated with Cucumber mosaic virus is infected with the virus and subsequently recovers from infection by RNA silencing

Distribution of Cucumber mosaic virus (CMV) in shoot meristem tissue of CMV-inoculated tobacco was successively analyzed with immunohistochemical microscopy and in situ hybridization. CMV signals were detected in the tissue at 7 days postinoculation (dpi), but then they decreased and disappeared after 14dpi. Detailed observation confirmed CMV invasion of shoot apical meristem at 6–8dpi. Short interfering RNA corresponding to CMV RNAs was first detected at 7dpi and was detected up to 24dpi. These results suggest that the shoot meristem tissue is infected with CMV but subsequently recovers from the infection by RNA silencing.     

Amino acid 129 in the coat protein of Cucumber mosaic virus primarily determines invasion of the shoot apical meristem of tobacco plants

We previously reported that a strain of Cucumber mosaic virus (Pepo CMV) invaded the shoot apical meristem (SAM, tunica corpus) of tobacco plants at 6–8 days postinoculation (dpi), contrary to earlier observations. To identify a viral factor determining the ability to invade the SAM, we inoculated plants with two other CMV strains, MY17 and Y, and tested the three strains in this study. Immunohistochemical microscopy revealed that MY17 CMV invaded the SAM at 7 dpi, the same as Pepo CMV, but Y CMV did not, even at 21 dpi. Using RNA pseudorecombinants between Pepo and Y CMV, we found that Pepo RNA 2 affected the rate of SAM invasion, and Pepo RNA 3 was required for successful SAM invasion. Inoculation with RNA 1 and RNA 2 from Y CMV and RNA 3 containing the chimeric coat protein (CP) gene between Pepo and Y CMV or a Y RNA 3 point mutant containing a Ser-to-Pro substitution at position 129 in CP (Y129P) revealed that amino acid 129 of CP is the determinant for successful SAM invasion. The rate of SAM invasion of the pseudorecombinants and Y129P was consistent with the efficiency of cell-to-cell movement in the inoculated leaves, implying that SAM invasion by CMV strains may be due to efficient cell-to-cell movement.     

High resistance to rice yellow mottle virus in two cultivated rice cultivars is correlated with failure of cell to cell movement

Rice yellow mottle virus (RYMV) accumulation in protoplasts and whole plants was investigated in two highly resistant cultivars, Tog5681 (Oryza glaberrima) and Gigante (Oryza sativa). Three susceptible cultivars, i.e. one O. glaberrima Tog5673 and two O. sativa (IR64, Ac. 2428), and a partially resistant cultivar (Azucena) were used as control. After inoculation, accumulation of coat protein (CP) and viral RNA were monitored on protoplasts, inoculated leaves, sheaths of inoculated leaves and newly infected leaves by serological and Northern blot analysis. Viral RNA accumulated to a similar extent in protoplasts from all cultivars studied. In contrast, three distinct in planta behaviors were noted. In susceptible plants (IR64, Tog5673 and Ac. 2428), there was high CP and RNA accumulation at 5 d.p.i. in whole plants, suggesting that cell to cell and vascular movements occurred before 5 d.p.i. in inoculated leaves. The second behavior concerned Azucena, which showed a delay (around 7 d.p.i.) of viral accumulation in inoculated leaves. The third behavior involved the highly resistant cultivars Tog5681 and Gigante. CP and viral RNA were not detected in these cultivars. The comparison of viral accumulation in protoplasts and plants suggested that resistance of the highly resistant cultivars Tog5681 (O. glaberrima) and Gigante (O. sativa) was not due to the inhibition of virus replication but rather to the failure of cell to cell movement.     

Incidence of viruses in <Emphasis Type="Italic">Alstroemeria</Emphasis> plants cultivated in Japan and characterization of <Emphasis Type="Italic">Broad bean wilt virus-2, Cucumber mosaic virus</Emphasis> and <Emphasis Type="Italic">Youcai mosaic virus</Emphasis>

Alstroemeria plants were surveyed for viruses in Japan from 2002 to 2004. Seventy-two Alstroemeria plants were collected from Aichi, Nagano, and Hokkaido prefectures and 54.2% were infected with some species of virus. The predominant virus was Alstroemeria mosaic virus, followed by Tomato spotted wilt virus, Youcai mosaic virus (YoMV), Cucumber mosaic virus (CMV), Alstroemeria virus X and Broad bean wilt virus-2 (BBWV-2). On the basis of nucleotide sequence of the coat protein genes, all four CMV isolates belong to subgroup IA. CMV isolates induced mosaic and/or necrosis on Alstroemeria. YoMV and BBWV-2 were newly identified by traits such as host range, particle morphology, and nucleotide sequence as viruses infecting Alstroemeria. A BBWV-2 isolate also induced mosaic symptoms on Alstroemeria seedlings.     

Molecular characterization of A2 and D strains of Soybean mosaic virus, which caused a recent virus outbreak in soybean cultivar Sachiyutaka in Chugoku and Shikoku regions of Japan

Coat protein sequences of two isolates in strain A₂ and five isolates in strain D of Soybean mosaic virus (SMV), which caused a recent mosaic outbreak in soybeans (cv. Sachiyutaka) in Chugoku and Shikoku in Japan, were compared to published data on 15 other Asian-origin isolates. Sequence comparison and cluster analysis showed that SMV isolates of strain A₂ from these districts were closely related, as were those of strain D, but strains A₂ and D were not. Thus, the two strains may have different origins and be carried through seed transmission.     

Evidence of a new Tomato yellow leaf curl virus in Japan and its detection using PCR

A new isolate of Tomato yellow leaf curl virus (TYLCV) has been identified from tomato plants in Kochi Prefecture in Japan and designated TYLCV-[Tosa]. The complete nucleotide sequence of the isolate was determined and found to consist of 2781 nt. In phylogenetic analyses of entire nucleotide sequences, TYLCV-[Tosa] was delineated as a single branch and was more closely related to TYLCV-[Almeria] than TYLCV isolates Ng, Sz, or Ai reported in Japan, which had spread since 1996. Isolate TYLCV-[Tosa] is suggested to be a newly introduced, novel isolate of TYLCV that dispersed into Kochi Prefecture. In addition, a rapid method using the polymerase chain reaction to separate TYLCV isolates into four genetic groups was established. This method would be useful for reliable diagnosis based on genetic differences among isolates of TYLCV.The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under accession numbers AB192965 and AB192966     

Characterization and detection ofCucumber green mottle mosaic virus in Greece

The host range specificity of Greek isolates ofCucumber green mottle mosaic virus (CGMMV) was determined and the ability of the virus to retain its infectivity in naturally contaminated soil, after storage at 4°C for at least 10 months, was established. An immunocapture RT-PCR protocol was developed for the detection of the virus and proved to be 10⁵ times more sensitive than DAS-ELISA and 10² times more sensitive than F(ab’)₂-ELISA using F(ab’)₂ fragments that were prepared from an antiserum, which was raised against a local virus isolate. In order to clarify dissimilarities that were revelaed between the coat protein (CP) genes of the Greek isolates after restriction mapping of their respective PCR products, the CP genes of three isolates were sequenced and found to be very similar but not identical to the CP gene of CGMMV-SH. http://www.phytoparasitica.org posting Aug. 27, 2002.     

A novel approach to spider mite control based on expression of sarcotoxin IA peptidevia a virus-vector system in plants

Control of the spider miteTetranychus cinnabarinus Boisduval is problematic, and there is a pressing need for efficient, non-hazardous and inexpensive strategies for limiting the damage it causes. The gene for the anti-bacterial peptide sarcotoxin IA of the flesh flySarcophaga peregrina was cloned into the nonpathogenic potyvirus-based vector system ZYMV-AGII (Zucchini yellow mosaic virus-AGII). Expression of this peptidevia the AGII vector was detected in infected squash leaves and was not deleterious to the host plant. Leaf discs of squash infected with the recombinant virus AGII-sarcotoxin IA were tested for spider mite control under laboratory conditions. Spider mite egg production on plants expressing the sarcotoxin IA gene was decreased by a factor of two or three compared with that on AGII-infected plants or healthy leaf discs, respectively. In contrast to its effect on oviposition, sarcotoxin IA expressing squash did not significantly affect the mortality and the ability to repel spider mites. Crude extract from squash leaves infected with AGII-sarcotoxin IA was also found to cause a significant decrease of mite fecundity compared with extracts from AGII-treated or healthy plants and also caused a rise in mite mortality. Our results demonstrate that sarcotoxin IA affects mite fecundity and, to a lesser degree, mortality, and shows potential for controlling spider mites in the field.     

黄瓜花叶病毒和马铃薯Y病毒混合侵染烟株对烟蚜取食行为的影响

为探究黄瓜花叶病毒(Cucumber mosaic virus,CMV)、马铃薯Y病毒(Potato virus Y,PVY)混合侵染烟株对烟蚜取食行为的影响,利用刺探电位图谱(electrical penetration graph,EPG)技术记录了烟蚜在健康烟株与CMV、PVY混合侵染后不同发病级别烟株上的取食波形。结果显示:烟蚜在健康烟株上的刺探次数最少,在感病烟株上的C波总持续时间均显著长于健康烟株;第1次到达韧皮部前的刺探次数,健康植株上仅为4.00次,3级感病烟株上的为健康烟株上的2倍;在健康烟株上E2波总持续时间为120.65 min,极显著大于2级和3级感病烟株;刺探过程中,感病烟株上的pd波出现次数均高于健康烟株,且pd波II-1和II-3亚波的持续时间也显著高于健康烟株。研究表明,CMV、PVY混合侵染烟株可降低寄主对烟蚜的适合度,且能促进烟蚜对病毒的传播。     

Lonicera latent virus,a new carlavirus serologically related to poplar mosaic virus: some properties and inactivation in vivo by heat treatment

A virus with elongate particles (656 nm) was isolated from severalLonicera species. This virus, apparently belonging to the carlavirus group, is serologically distantly related to shallot latent virus and closely related to poplar mosaic virus. The inability to infect poplar and two other hosts of poplar mosaic virus characterizes the virus fromLonicera as a new virus which was namedLonicera latent virus.The virus was easily sap-transmissible but was not transmitted byMyzus persicae.Dilution end-point was about 10^–3, thermal inactivation between 65°C and 80°C and ageing in vitro 1–6 days.Heat treatment, combined with tip-rooting appeared to be a good method to eliminate the virus from severalLonicera species and cultivars.Samenvatting In verschillende soorten en cultivars van het geslachtLonicera (kamperfoelie) blijkt een virus voor te komen dat gemakkelijk door sapinoculatie kan worden overgebracht op kruidachtige planten.Een tegen gezuiverd virus bereid antiserum had een titer van ca. 4096. Er kon mee worden aangetoond dat het virus van kamperfoelie serologisch nauw verwant is met populieremozaïekvirus (Tabel 1). Het virus van kamperfoelie is echter niet in staat om populier,Phaseolus vulgaris Bataaf enVigna sinensis te infecteren en wordt mede daarom als een afzonderlijk virus beschouwd. Het wordt aangeduid als latent kamperfoelievirus (Lonicera latent virus) en behoort evenals populieremozaïekvirus tot de carlavirusgroep (aardappelvirus-S-groep).Het virus blijkt vrij gemakkelijk te kunnen worden geëlimineerd door besmette kamperfoelieplanten gedurende ongeveer zes weken een warmtebehandeling (37°C) te geven en daarna de uiterste toppen (1 cm) te stekken. Van verschillende cultivars werd op deze wijze virusvrij uitgangsmateriaal verkregen.     

The <Emphasis Type="Italic">cyv-2</Emphasis> resistance to <Emphasis Type="Italic">Clover yellow vein virus</Emphasis> in pea is controlled by the eukaryotic initiation factor 4E

The same mutant allele of eukaryotic initiation factor 4E (eIF4E) that confers resistance to Pea seed-borne mosaic virus (sbm-1) and the white lupine strain of Bean yellow mosaic virus (wlv) also confers resistance to Clover yellow vein virus (ClYVV) in pea. The eIF4E genes from several pea lines were isolated and sequenced. Analysis of the eIF4E amino acid sequences from several resistant lines revealed that some lines, including PI 378159, have the same sequence as reported for sbm-1 and wlv. When eIF4E from a susceptible pea line was expressed from a ClYVV vector after mechanical inoculation of resistant PI 378159, the virus caused systemic infection, similar to its effects in susceptible line PI 250438. The resistance to ClYVV in line PI 378159 was characterized through a cross with PI 193835, which reportedly carries cyv-2. Mechanical inoculation of the F1 progeny with ClYVV resulted in no infection, indicating that the resistance gene in PI 378159 is identical to cyv-2 in PI 193835. Furthermore, particle bombardment of pea line PI 193835 with infectious cDNA of ClYVV (pClYVV/C3-S65T) resulted in the same resistance mode as that described for PI 378159. These results demonstrate that the resistance to ClYVV conferred by cyv-2 is mediated by eIF4E and that cyv-2 is identical to sbm-1 and wlv.