Sobemovirus Research Articles

Characterization of cymbidium chlorotic mosaic virus from cymbidium tortisepalum in China

The complete nucleotide sequence of isolate YN of the putative sobemovirus Cymbidium chlorotic mosaic virus (CyCMV) from Cymbidium tortisepalum plants showing chlorotic and necrotic spots in Yunnan province (southwest China) was determined by deep sequencing. Dips from symptomatic leaves showed that this virus has icosahedral particles ca. 30 nm in diameter. The viral genome is a positive-strand RNA molecule 4,081 nt in size (GenBank accession No. KR996515) encoding four open reading frames with an organization similar to that described for sobemoviruses. The complete sequence of CyCMV-YN shares 89.5% identity at the nucleotide level with that of CyCMV-JP isolated from Cymbidium goeringii in Japan. This is the first report of a sobemovirus infecting orchid in China.

Response of cowpea lines to inoculation with four seed transmitted viruses of cowpea.

This study evaluated the performance cowpea genotypes in the field in Ibadan, Nigeria for response to infection induced by four seed transmitted viruses of cowpea. The experiment was laid out in split plot design withthree replicates. Cowpea mottle virus genus Carmovirus (CMeV) produced infection in 14 of the 15 lines, Bean common mosaic virus genus Potyvirus - blackeye cowpea strain (BCMV – BlC) in 12, Cowpea aphid-borne mosaicvirus genus Potyvirus (CABMV) in 11 and Southern bean mosaic virus genus Sobemovirus (SBMV) in 6. BCMV – BlC significantly reduced (p

Screening Cowpea (<I>Vigna unguiculata</I> (l) walp) lines for infection responses to some Cowpea Viruses in Nigeria

Thirty-three cowpea varieties were screened in a screen-house in Ibadan, Nigeria for responses to four cowpea viruses; namely, Bean common mosaic potyvirus - blackeye cowpea strain (BCMV-BlC), Cowpea aphid-borne mosaic potyvirus (CABMV), Cowpea Mottle Carmovirus (CMeV) and Southern bean mosaic sobemovirus (SBMV). 33 x 5 factorial experiment in completely randomised design was used, disease severity was measured at the second and sixth weeks after mechanical inoculation of the viruses and scored from 1 (no infection) to 5 (very severe infection). Symptomless plants were serologically tested with Protein – A sandwich enzyme linked immunosorbent assay (PAS-ELISA) to distinguish lines with latent infection from none infected lines. The yield in 2000 was not significantly (p KEY WORDS: Cowpea viruses, Disease incidence, Cowpea, Vigna, ELISA. Global Jnl Pure and Applied Sciences Vol.10(4) 2004: 473-478

Virus susceptibility and resistance of Hungarian pepper varieties

The aim of our study was to examine susceptibility or resistance of 18 pepper varieties to four viruses [tobacco mosaic
 tobamovirus (TMV), sowbane mosaic sobemovirus (SoMV), NTN strain of potato Y potyvirus (PVYNTN) and cucumber mosaic cucumovirus (CMV). Out of the 18 varieties, 13 were resistant to CMV infection. Thirteen varieties were susceptible to TMV, while five ones (Dabora Fl, Brill Fl, Feherozon Synthetic, Ciklon Fl, Cecil Fl) showed only local hypersensitive reaction. All of the tested pepper varieties showed resistance to SoMV. Eight varieties (Tuba, Fehérözön Synthetic, Boni, Alba Regia, Korona, Édesalma, Cecil Fl, Star) were found to be resistant to PVYNTN. Out of the examined varieties five (Boni, Alba Regia, Korona, Édesalma, Star) were resistant to three viruses (SoMV, CMV and PVYNTN). Only one (Cecil F1) displayed complex, extreme resistance to SoMV, PVYNTN, CMV and hypersensitive reaction to TMV, therefore this hybrid is very important in pepper breeding and growing for virus resistance.

Survey on cowpea virus incidence and distribution in Nigeria

Enzyme-linked immunosorbent assay (ELISA) was used to detectviruses in649 cowpea leafsamples collectedfrom115 fields during a 3-year survey carried out from 1991 to 1993 throughout all agroecological zones in Nigeria. Six viruses, cowpea aphid-borne mosaic potyvirus (CAMV), blackeye cowpea mosaic potyvirus (BICMV), southern bean mosaic sobemovirus (SBMV), cowpea mottle carmovirus (CMoV), cowpea (yellow) mosaic comovirus (CpMV) and the cowpea strain of cucumbermosaic cucumovirus (CMV-CS)were detectedin 390 outofthe 649 samples assayed. There was considerable variation in both disease incidence and virus distribution in the different crop habitats within and between seasons. Thus, while SBMV had the highest incidence (27.4%) and was the most prevalent (66.7% in 1991, CAMV had the highest incidences (11.3% and 28.8%, respectively) and was the most prevalent 33% and 68%, respectively) in 1992 and 1993. CpMV and CMoV remained consistently moderate both in incidence and prevalence throughout the duration of the survey. The detection of the three beetletransmitted sphericalviruses (SBMV, CpMV and CMoV)in the Sudanand Sahel Savanna indicates that there is no ecological restriction to the distributionofanyoftheviruses.Incidence ofmultipleinfectionofuptofour and five viruses in individual samples was observed, but mixed infection with two viruses was more prevalent (13%). The potential for horizontal resistance breeding based on common vector transmission is discussed.

Nucleotide Sequence of RNA from the Sobemovirus Found in Infected Cocksfoot Shows a Luteovirus-Like Arrangement of the Putative Replicase and Protease Genes

A virus found in naturally infected cocksfoot plants had a host range, symptom expression characteristics, and a particle morphology similar to those of cocksfoot mottle sobemovirus (CoMV). The viral RNA was cloned and sequenced (GeneBank accession number L40905). Computer-assisted analysis of the 4,083-nt RNA sequence revealed four open reading frames (ORFs) flanked by 5'- and 3'-untranslated regions of 69 and 228 nt, respectively. The 3'-proximal ORF putatively coded for a 27.6-kDa product that was obviously homologous to the coat proteins of southern bean mosaic sobemovirus (SBMV) and rice yellow mottle sobemovirus (RYMV), which agrees with the identification of this virus as a Russian isolate of CoMV. This virus genome is closely related to that of a recently sequenced Norwegian isolate of CoMV. The 5' end of the subgenomic RNA was mapped 35 nt upstream of the coat-protein ORF initiation codon. Despite the considerable sequence similarity of the CoMV coat protein, putative RNA-dependent RNA polymerase (RDRP), and protease with the analogous proteins of SBMV and RYMV, CoMV differed from other sobemoviruses in the arrangement and expression of the RDRP and protease ORFs. The CoMV genome organization resembled those of the luteovirus genomes, i.e., the two ORFs overlap out of frame and are hypothesized to yield a frameshift fusion product.

Entry of Ingested Plant Viruses into the Hemocoel of the Beetle VectorDiabrotica undecimpunctata howardi

Southern bean mosaic sobemovirus (SBMV) and the cowpea strain of tobacco mosaic tobamovirus (CP-TMV) are found in the hemocoel of some beetle vectors after they have fed on infected plants. The location in the alimentary canal through which ingested plant viruses enter the hemocoel of the spotted cucumber beetle Diabrotica undecimpunctata howardi was studied. Immunofluorescent and electron microscopy were used to detect the presence of ingested viruses in the gut lumen and the epithelial cells lining the midgut of the spotted cucumber beetle. Virusspecific immunofluorescent microscopy detected bean pod mottle virus and tobacco ringspot virus only in the lumen of the gut; these two viruses cannot be detected in the hemocoel [...]

Natural Occurrence of Five Seedborne Cowpea Viruses in Pakistan

A total of 151 cowpea leaf samples with viruslike symptoms were collected from 13 districts of Punjab and North-West Frontier Province (NWFP) of Pakistan during the summers of 1990 and 1991. Desiccated samples were tested by direct antigen coating (DAC) or double antibody sandwich (DAS) enzyme-linked immunosorbent assay (ELISA) for the presence of seven viruses known to be seedborne in cowpea: blackeye cowpea mosaic (BICMV) and cowpea aphid-borne mosaic (CABMV) potyviruses, cucumber mosaic (CMV) cucumovirus, cowpea mosaic (CPMV) and cowpea severe mosaic (CSMV) comoviruses, cowpea mottle carmovirus (CPMoV), and southern bean mosauc sobemovirus (SBMV)

Cowpea Viruses in Senegal, West Africa: Identification, Distribution, Seed Transmission, and Sources of Genetic Resistance

Viral diseases of cowpea (Vigna unguiculata subsp. unguiculata) in Senegal were surveyed during the rauny seasons of 1990 and 1991. Sixty-six symptomatic plant samples from five production areas were assayed for seven viruses by enzyme-linked immunosorbent assay (ELISA). Four recognized viruses, cowpea aphid-borne mosaic potyvirus (CABMV), cowpea mottle carmovirus (CPMoV), cowpea severe mosaic comovirus (CSMV), and southern bean mosaic sobemovirus (SBMV), were detected in 34, 2, 1, and 1 samples, respectively. All are seed-transmissible in cowpea. Variants of an unknown potyvirus were also detected in 21 samples. These variants occurred principally in new, improved CABMV-resistant cowpea genotypes, and their combined incidence in plant samples was exceeded only by CABMV

Transmission of sowbane mosaic virus by Thrips tabaci in the presence and absence of virus‐carrying pollen

SummaryWhen pollen of sowbane mosaic sobemovirus (SoMV)‐infected Chenopodium amaranticolor was dusted onto C. amaranticolor and C. quinoa test seedlings which were then infested with 5–10 adult Thrips tabaci, SoMV was transmitted to 25%C. amaranticolor and 88% of C. quinoa plants. Five hours access of T. tabaci to pollen‐contaminated C. quinoa seedlings was sufficient for SoMV transmission, but 1 h was not. SoMV was also transmitted when T. tabaci was mixed with pollen of C. amaranticolor and then placed on C. quinoa test seedlings. Further, plant‐to‐plant transmission of SoMV occurred in the absence of virus‐carrying pollen when T. tabaci was caged on infected non‐flowering C. amaranticolor or C. quinoa for 1–8 days and then adults transferred to C. quinoa test seedlings. This is the first time that thrips have been shown to be a vector of SoMV, and that a virus outside the ilarvirus group is reported to be transmitted using pollen and thrips.

Effect of viruses on pollen morphology

Many pollen grains from Chenopodium quinoa plants infected with sowhane mosaic sobemovirus (SMV) were collapsed, grooved and had sunken opercula, whereas those from the first flowers of virus‐free plants were smooth, rounded and with protuberant opercula. However, pollen grains from later flowers of virus‐free plants were similar in appearance to those from the virus‐infected plants. Similar but less obvious symptoms were found in pollen of Plantago lanccoiata infected with either ribgrass mosaic tobamovirus or broad bean wilt virus. No symptoms were found in pollen of Hordeum vulgare cv. clipper, H. sponiaitcum or Triticum acstivum infected with barley suripe mosaic hordeivirus, nor in pollen of a Cardaminc sp. naturally infected with a strain of turnip yellow mosaic tymovirus. The symptoms, even those shown by pollen from SMV‐infected C quinoa, seemed not to be sufficiently characteristic for diagnosis of virus infection.