Mosaic Potyvirus Research Articles

Strains of Turnip mosaic potyvirus as defined by the molecular analysis of the coat protein gene of the virus

Turnip mosaic virus (TuMV) is a member of the potyvirus genus with a wide host range and highly variable in its biological characteristics. Analysis of the CP gene sequences from databases, combined with the experimental analysis of the CP gene of further isolates, using data derived from sequence or restriction analysis, has allowed the genetic classification of 60 TuMV isolates or sequences. Two main genetic clusters MB (mostly Brassica isolates) and MR (mostly Radish isolates) were found, together with several apparently independent lineages. Isolates in the latter could be grouped as Intermediate between Brassica and Radish clusters (IBR) or outside Brassica and Radish clusters (OBR), according to their genetic distance to the main clusters. The genetic diversity of TuMV isolates deposited in the databases was increased with the sequences of the CP gene of seven selected isolates, mainly belonging to IBR or OBR groups. There was a correlation between the MR genetic cluster and JPN 1 serotype.

Symptom Variances in Mixed Infections of Six Turnip mosaic virus and One Ribgrass mosaic vims Isolates in Crucifers

Turnip mosaic Potyvirus (TuMV) and Ribgrass mosaic Tobamovirus (RMV) are major viruses infecting crucifer crops in Korea. RMV-FG22 was isolated from oriental cabbage. TuMV isolates were TuMV-CA7 from oriental cabbage, TuMV-TU and TuMV-TU2 from turnip, TuMV-RA from rape, TuMV-ST from stock, and TuMV-R9 from radish. The six isolates of TuMV were classified by symptom expression in inbred lines of crucifers. TuMV-CA7 and TuMV-TU isolates infected mostly oriental cabbages; TuMV-ST, TuMV-TU2, and TuMV-R9 infected radishes; and TuMV-RA infected both oriental cabbages and radishes. Crops used in six combinations of mixed infections were 'Tambok' cultivar resistant to TuMV,'SSD63' susceptible inbred line of oriental cabbage, pure line of leaf mustard, and‘Daeburyungyeorum’cultivar of radish. External symptoms in 'Tambok' and radish by each of the six single infections of TuMV showed similar results by bioassay. Synergistic response of necrotic death occurred within 1 week after inoculation in all combinations mixed with TuMV and RMV-FG22 on leaf mustard. In oriental cabbage 'SSD63' , synergism of necrosis occurred in four TuMV isolates, but not in TuMV-ST and TuMV-R9. In oriental cabbage 'Tambok' , synergism was expressed only in two combinations of RMV-FG22+TuMV-CA7 and RMV-FG22+TuV-TU, but other combinations had the same symptoms produced by RM-FG22. In radish‘Daeburyungyeorum’, only mild mosaic symptoms were induced by combinations of RMV-FG22+TuMV-CA7, RMV-FG22+TuMV-TU, RMV-FG22+TuMV-RA, and RMV-FG22+TuMV-R9. Mosaic and severe mosaic were induced in combinations of RMV-FG22 +TuMV-TU2 and RMV-FG22+TuMV-ST, respectively.

Ultrastructural Differences in Mixed Infections of Six Turnip mosaic virus and One Ribgrass mosaic virus Isolates in Crucifers

Six isolates of Turnip mosaic Potyvirus (TuMV) namely, TuMV-CA7 from oriental cabbage, TuMV-TU and TuMV-TU2 from turnip, TuMV-RA from rape, TUMV-ST from stock, and TuMV-R9 from radish, and Ribgrass mosaic Tobamovirus (RMV-FG22) from oriental cabbage were isolated. Three kinds of characteristics of the six TuMV isolates were sorted by bioassay: TuMV-CA7 and TuMV-TU isolates infected mostly oriental cabbages; TuMV-ST, TuMV-TU2, and TuMV-R9 infected radishes; and TuMV-RA infected both oriental cabbages and radishes. Mixed infections of crucifers were RMV-FG22+TuMV-CA7, RMV-FG22+TuMV-TU, RMV-FG22+TuMV-RA, RMV-FG22+TuMV-ST, RMV-FG22 +TuMV-TU2 and RMV-FG22+TuMV-R9. Crops used were 'Tambok' cultivar resistant to TuMV, 'SSD63' susceptible inbred line of oriental cabbage, pure line of leaf mustard and 'Daeburyungyeorum' cultivar of radish. New specific ultrastructures of nonagon-like ring (NLR) and spiral aggregates (SA) by mixed infection with TuMV and RMV were formed in cells of crucifer plants. The NLR was made by a TuMV surrounded loosely by nine RMV particles, and the SA was formed spirally by full mixed of two virus particles. The SA had some NLR in its center, which was observed from cross sectioned SA. Host plants with specific ultrastructures expressed synergistic symptoms. Specific ultrastructures of NLR and SA were formed in combinations of RMV-FG22 and in TuMV-CA7, TuMV-TU, or TuMV-RA that could infect oriental cabbages. How-ever, no specific ultrastructures and mixing of the two virions in the same cell were observed in combinations of RMV-FG22, and TuMV-57, TuMV-TU2, or TuMV-R9 isolates haying virulence in radishes.

Gene silencing in transgenic soybean plants transformed via particle bombardment.

Transgenes are susceptible to silencing in plants especially when multiple copies of the gene of interest are introduced. Transgenic plants derived by particle bombardment, which is the common method for transforming soybean, have a tendency to have multiple integration events. Three independent transgenic soybean plants obtained via particle bombardment were analyzed for transgene silencing. A GUS transgenic soybean line had at least 100 copies of the GUS gene while there were approximately 60 copies of the transgene in the two soybean lines transformed with a 15-kDa zein storage protein gene from maize. Soybean plants transformed with the GUS gene showed variable GUS expression. The coding region and promoter of the GUS gene in the plants with low expression of GUS were heavily methylated. Variability in GUS expression was observed in the progeny of the high expressors in the T(2) and T(3) generations as well. Expression level of the 15-kDa zein gene in transgenic soybean plants showed correlation with the level of transgene methylation. The helper component-proteinase from potyviruses is known to suppress post-transcriptional gene silencing. Transgenic plants were inoculated with the soybean mosaic potyvirus (SMV) to test possible effects on transgene silencing in soybean. Infection with SMV did not suppress transgene silencing in these plants and suggests that the silencing in these plants may not be due to post-transcriptional gene silencing.

Infectivity of in vitro transcripts of Johnsongrass mosaic potyvirus full-length cDNA clones in maize and sorghum.

In vitro transcripts of full-length cDNA clones of the Johnsongrass strain of Johnsongrass mosaic potyvirus (JGMV-Jg) were infectious on maize and sorghum when inoculated by mechanical or by biolistic bombardment. Two of the cDNA clones with spontaneous mutations in the coat protein were not infectious. Sequence differences between infectious and non-infectious transcripts revealed that alteration of inferred amino sequences, near or in the N-terminus of the coat protein, profoundly affected the infectivity of transcripts. Transcripts of chimeric full-length cDNA of JGMV-Jg, containing coat protein sequences from the Krish-infecting strain of JGMV, were infectious in Krish resistant sorghums.

Detection of Japanese yam mosaic virus by RT-LAMP

Arapid and simple procedure is described to detect the genomic RNA molecule of Japanese yam mosaic potyvirus (JYMV). This method, named RT-LAMP, allows direct detection of RNA from infected plants without careful RNA extraction, rapid thermal cycling and gel electrophoresis. RT-LAMP was successfully applied to leaves, propagules and roots of Japanese yam infected with JYMV. One of the characteristics of the RT-LAMP method is its ability to synthesize an extremely large amount of DNA. Accordingly, a large amount of by-product, pyrophospate ion, is produced yielding a white precipitate of magnesium pyrophosphate in the reaction mixture. The presence or absence of this white precipitate allows easy detection of the amplification of JYMV genomic RNA without gel electrophoresis.

Diverse RNA viruses elicit the expression of common sets of genes in susceptible Arabidopsis thaliana plants.

Systemic infections of plants by viruses require that viruses modify host cells in order to facilitate infections. These modifications include induction of host factors required for replication, propagation and movement, and suppression of host defense responses, which are likely to be associated with changes in host gene expression. Past studies of the effects of viral infection on gene expression in susceptible hosts have been limited to only a handful of genes. To gain broader insight into the responses elicited by viruses in susceptible hosts, high-density oligonucleotide probe microarray technology was used. Arabidopsis leaves were either mock inoculated or inoculated with cucumber mosaic cucumovirus, oil seed rape tobamovirus, turnip vein clearing tobamovirus, potato virus X potexvirus, or turnip mosaic potyvirus. Inoculated leaves were collected at 1, 2, 4, and 5 days after inoculation, total RNA was isolated, and samples were hybridized to Arabidopsis GeneChip microarrays (Affymetrix). Microarray hybridization revealed co-ordinated changes in gene expression in response to infection by diverse viruses. These changes include virus-general and virus-specific alterations in the expression of genes associated with distinct defense or stress responses. Analyses of the promoters of these genes further suggest that diverse RNA viruses elicit common responses in susceptible plant hosts through signaling pathways that have not been previously characterized.

Virus Disease Problems on Field Cucumber in Hungary with Some International Aspects

Viruses caused severe yield losses of field cucumber in Hungary last years. Field surveys have been carried out on field cucumber to evaluate virus infection in the region of Gyor-Moson-Sopron county. Virus infection was determined on the basis of symptoms, biotest and with DAS-ELISA serological method for the presence of 15 viruses. The virus vector aphid flight was monitored by Moericke yellow water pan. On the basis of field surveys 100% virus infection has been observed in cucumber fields. Virus symptoms were various, depending on varieties, environmental factors, viruses and strains. Out of the viruses investigated only three [Cucumber mosaic cucumovirus (CMV) (DTL serotype); Zucchini yellow mosaic potyvirus (ZYMV) and Watermelon mosaic 2 potyvirus (WMV-2)] have been occurred on cucumber samples. Biological tests confirmed the results of DAS-ELISA. There was much difference, regarding the frequency of viruses. ZYMV was dominant in 1998, while CMV was dominant in 1999. The proportion of the complex infection was very high. Till now, besides CMV other viruses cannot be detected from weeds in cucumber ecosystems. The peak of aphid flight was in the middle of June and later a secondary peak was observed at the beginning of July, which coincided with the appearance of the first virus symptoms. Regarding, that cucumber production occurs in fields at the same place year by year, soil borne virus vectors may play important role in virus infection. To reduce virus infection we can suggest using of light summer oils, which prevents virus transmission by aphids. It is concluded that team work of virologists, pathologists, growers, technologists and the breeders is necessary to solve virus problems of field cucumber in Hungary.

The Canadian Phytopathological Society Annual Meeting, Waterton Lakes National Park, Alberta, 2002

The Canadian Phytopathological Society Annual Meeting, Waterton Lakes National Park, Alberta, 2002

Screening of sugarcane mosaic potyvirus (SCMV) from cane stalk juice

Sugarcane mosaic potyvirus (SCMV) is widely infected in most of the sugarcane growing belts of India causing intervienal chlorotic specks, streaks or stripes especially on young leaves. Earlier only the infected leaves extract were commonly used for the screening of this virus by serological methods. However, in the present study, direct antigen coating enzyme linked immunosorbant assay (DAC-ELISA) and dot blot immunoassay (DIBA) were standardized for the detection of the virus in infected cane stalk juice samples. Juice dilution up to 1:150 was found satisfactory for the detection of SCMV in DAC-ELISA and DIBA serological tests. Our results suggest that cane stalk juice could be equally satisfactory as virus infected leaf samples and can be used in commercial screening of sugarcane mosaic potyvirus.

A non-aphid-transmissible isolate of bean yellow mosaic potyvirus has an altered NAG motif in its coat protein.

An isolate of Bean yellow mosaic virus (BYMV) not transmitted by aphids (NAT) was compared with the aphid-transmissible isolate (MI) from which it was derived. For each isolate, the sequence of the coat protein and parts of the helper component was determined. A single nucleotide substitution caused a NAG to NAS alteration in the coat protein of the non aphid-transmissible isolate. Loss of aphid transmissibility in isolate BYMV(MI)-NAT was most likely caused by this mutation within the NAG motif. Systemic movement and accumulation of the virus in infected plants were not affected by the mutation.

Evaluation of Resistance in Soybean Germplasm to Soybean Mosaic Potyvirus under Field Conditions

Evaluation of Resistance in Soybean Germplasm to Soybean Mosaic Potyvirus under Field Conditions

Loss-of-Susceptibility Mutants of Arabidopsis thaliana Reveal an Essential Role for eIF(iso)4E during Potyvirus Infection

The Arabidopsis thaliana-potyvirus system was developed to identify compatibility and incompatibility factors involved during infection and disease caused by positive-strand RNA viruses [1, 2]. Several Arabidopsis mutants with increased susceptibility to Tobacco etch potyvirus (TEV) were isolated previously [1], revealing a virus-specific resistance system in the phloem [3–5]. In this study, Arabidopsis mutants with decreased susceptibility to Turnip mosaic potyvirus (TuMV) were isolated. Three independent mutants that conferred immunity to TuMV were isolated and assigned to the same complementation group. These mutants were also immune or near-immune to TEV but were susceptible to an unrelated virus. The locus associated with decreased susceptibility was named loss-of-susceptibility to potyviruses 1 (lsp1). The LSP1 locus was isolated by map-based cloning and was identified as the gene encoding translation factor eIF(iso)4E, one of several known Arabidopsis isoforms that has cap binding activity. eIF4E and eIF(iso)4E from different plant species were shown previously to interact with the genome-linked protein (VPg) of TEV and TuMV, respectively. Models to explain the roles of eIF(iso)4E during virus infection are presented.

Reflective mulches for management of aphids and aphid-borne virus diseases in late-season cantaloupe ( Cucumis melo L. var. cantalupensis)

A complex of aphids and several mosaic virus diseases can cause major losses in cucurbitaceous crops grown in the inland valleys of California. Three field experiments were conducted to test and compare the effectiveness of reflective polyethylene and biodegradable, synthetic latex spray mulches for management of aphids and aphid-borne virus diseases of late-season cantaloupe ( Cucumis melo L. var. cantalupensis cv. Primo) in the San Joaquin Valley. Beneficial responses were obtained from the reflective mulches, under conditions of high aphid populations and virus inoculum potential, during each of the experiments. Aphid numbers on leaves of plants growing over mulches were consistently lower than on those growing over bare soil. Onset of symptoms of cucumber mosaic cucumovirus, and watermelon mosaic and zucchini yellow mosaic potyviruses, were delayed 3–6 weeks in plants growing over the mulches, which was critical for initiation of normal flowering and fruiting. High virus disease incidence (100% incidence of foliar symptoms) reduced cumulative, marketable melon yields (number of fruit, fresh weight, and size) in the control plots to near zero in two of the three experiments. In each of the experiments, polyethylene or spray mulch treatments which completely covered each planting bed provided at least 9.5- and 2.5-fold increases in marketable yield, respectively. In the first two experiments, reflective mulches would have provided the difference between salable crops and total crop loss. Partial bed coverage with spray mulch, and alternate row applications of polyethylene film mulches, were less effective than complete coverage of every planted row.

Effect of Soybean Mosaic Potyvirus on Growth and Yield Components of Commercial Soybean Varieties

Effect of Soybean Mosaic Potyvirus on Growth and Yield Components of Commercial Soybean Varieties

Registration of Two Cranberry Bean Germplasm Lines Resistant to Bean Common Mosaic and Necrosis Potyviruses: USCR‐7 and USCR‐9

Registration of Two Cranberry Bean Germplasm Lines Resistant to Bean Common Mosaic and Necrosis Potyviruses: USCR‐7 and USCR‐9

Registration of Three Kidney Bean Germplasm Lines Resistant to Bean Common Mosaic and Necrosis Potyviruses: USLK‐2 Light Red Kidney, USDK‐4 Dark Red Kidney, and USWK‐6 White Kidney

Registration of Three Kidney Bean Germplasm Lines Resistant to Bean Common Mosaic and Necrosis Potyviruses: USLK‐2 Light Red Kidney, USDK‐4 Dark Red Kidney, and USWK‐6 White Kidney

Lettuce mosaic poty virus is the causal agent of a new disease inBupleurum spp.

Mosaic symptoms were seen on the ornamental plantBupleurum falcatum (Apiaceae) grown in a commercial nursery in Israel. Examination by electron microscopy (EM) of samples from diseased plants revealed elongated filamentous virus particles. Here we provide evidence thatB. falcatum is an alternate host for Lettuce mosaic potyvirus (LMV). Several lines of evidence indicated thatBupleurum was infected by LMV, including double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), immunosorbent electron microscopy, and sap and aphid transmission of LMV to lettuce and other host plants. Additionally, general primers derived from a conserved region of the 3’-terminus of the potyvirus genome were used in a reverse transcription-polymerase chain reaction (RT-PCR) assay and gave an expected amplification product of 672 bp. A similar approach was carried out to amplify the corresponding fragment from LMV-infected lettuce. The PCR product was cloned and sequenced; it encompassed an open reading frame encoding 153 amino acids and a 3’ untranslated region (UTR) of 273 nucleotides, very similar to the coat protein (CP) and the 3‵UTR nucleotide sequence, respectively, of other LMV isolates. Analysis of the amino acid sequences of the putative CP of theBupleurum isolate showed complete identity to the lettuce isolate of LMV. TheBupleurum isolate had no new nucleotide changes which have not been established in other published LMV strain sequences. It is concluded that LMV is the causal agent of the disease inB. falcatum in Israel.

Identification of viruses infecting pumpkins (Cucurbita pepo L) in Yugoslavia

This study was carried out in order to identify the major viruses infecting pumpkins (Cucurbita pepo)grown in Serbia. Leaf samples from virus-infected pumpkin plants were collected in mid-July 2001. Naked-seeded and hulled oil pumpkins, patty pan, zucchini and summer squash from three different locations were included (Table 1). Virus-infected plants showed different symptoms (Table 2 and Figures 1-4). Due to the great variability of the symptoms, the causal viruses could not be fully and precisely determined by visual examination only. The infected samples were tested by the biotest, as well as by two serological methods, ELISA and EBIA. Polyclonal antibodies raised against cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 1 (WMV-1), watermelon mosaic potyvirus 2 (WMV-2) and squash mosaic comovirus (SqMV) were used. In each of the 50 collected samples one or two viruses were detected (Tables 3 and 4). The most prevalent viruses infecting pumpkins were ZYMV (62%) and CMV (58%). WMV-2 was extremely rare.

Biological and serological characterization of viruses of summer squash crops in Yugoslavia

A survey on summer squash open field crops was carried out during 2000 and 2001 in order to identify the major viruses infecting these crops in different localities. Plants showed different types of symptoms: mild mosaic, chlorotic spotting, distinctive mosaic, blistering of leaf lamina leaf yellowing, deformation of leaf lamina, knobbed fruits and stunting of plants. The symptoms were very variable but showed the viral nature of the investigated summer squash diseases. The collected samples were tested by bioassay and by two serological methods ELISA and EBIA using cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 2 (WMV-2), zucchini yellow flack potyvirus (ZYFV) watermelon mosaic potyvirus 1 (WMV-1), squash mosaic comovirus (SqMV) and cucurbit aphid-borne yellows polerovirus (CABYV) polyclonal antisera. In all tested samples single or mixed infection with ZYMV, CMV and WMV-2 was detected. The most prevalent virus infecting summer squash was ZYMV. This is the first report of ZYMV, the most destructive virus infecting cucurbits, in Yugoslavia. It was also proven that the identified viruses are transmissible by Aphis gossypii in a non-persistent manner, but possible role of seed in virus transmission was not confirmed.