First Report of a Croton yellow vein mosaic virus (CYVMV) Associated with Tomato Leaf Curl Disease in India

Leaf curl disease symptoms were observed in tomato crop grown in a tomato field at Matera district of Bahraich, India, in March 2013 with an 85% disease incidence. The infected plants exhibited leaf curl symptoms accompanied with puckering, vein swelling and stunting of the whole plant. PCR carried out with begomovirus coat protein gene and DNA beta‐specific primer sets resulted in positive amplification of ~775 bp and 1.35 kbp, respectively, with all symptom‐bearing plant samples. BLASTn and phylogenetic analyses of CP gene sequences showed highest and close relationship with Croton yellow vein mosaic virus (CYVMV) isolates, while the phylogenetic study of betasatellite sequence showed distinct relationships with other begomovirus associated betasatellites reported from India and abroad. This is a first report of a CYVMV associated with tomato leaf curl disease in India.     

Biological Characterization and Complete Genome Sequence of a Possible Strain of Indian cassava mosaic virus from Jatropha curcas in India

The outbreak of a severe mosaic disease with a significant incidence was noticed on Jatropha curcas plants growing in Lucknow, Northern India. The causal virus was successfully transmitted by whiteflies (Bemisia tabaci) and grafting from naturally infected to healthy J. curcas plants. The association of Begomovirus with the mosaic disease of J. curcas was detected by PCR using primers specific to DNA‐A of Begomoviruses. Further, full‐length DNA‐A genome of ～2.7 kb was amplified by RCA followed by digestion with Bam HI restriction enzyme. Cloning and sequencing of obtained amplicons resulted in 2740 nucleotides of complete DNA‐A consisting of six ORFs and IR region (GenBank Accession HM230683 ). The sequence analysis revealed highest 85% similarities with Jatropha curcas mosaic virus, 77–84% with Indian cassava mosaic virus and 73–76% with Sri Lankan cassava mosaic virus isolates. Phylogenetic analysis of the Begomovirus isolate also showed a clear‐cut distinct relationship with earlier reported Begomoviruses from Jatropha curcas and other Begomoviruses. On the basis of the guidelines of the International Committee on Taxonomy of Viruses (ICTV‐2008), our virus isolate was identified as a possible strain of Indian cassava mosaic virus, and its name Jatropha mosaic India virus (JMIV) is proposed.     

Konjac mosaic virus Naturally Infecting Three Aroid Plant Species in Andhra Pradesh,India

The genomes of three potyvirus isolates from, respectively, naturally infected Colocasia esculenta, Caladium spp. and Dieffenbachia spp. in Andhra Pradesh, India, were amplified by RT‐PCR using degenerate potyvirus primers. Sequence analysis of RT‐PCR amplicons (1599 nucleotides) showed maximum identity of 97% with the KoMV‐Zan isolate of Konjac mosaic virus (KoMV) from Taiwan (A/C AF332872). The three isolates had a maximum identity of 99.4%. The length of coat protein (CP) gene of three isolates was 846 nucleotides encoding 282 amino acids with a deduced size of 32.25 kDa. The CP gene of the isolates had, respectively, 78.1–95.7% and 88.2–96.4% identity at nucleotide and amino acid levels with KoMV isolates. The CP gene of the three isolates had 93.1–100% (nucleotide) and 98.2–100% (amino acid) identity. The 3′‐UTR of the three isolates showed maximum identity of 91.1–100% identity between and with other KoMV isolates. In the CP amino acid–based phylogenetic analyses, the isolates branched as a distinct cluster along with known KoMV isolates. The three potyvirus isolates associated with mosaic, chlorotic feathery mottling, chlorotic spots, leaf deformation and chlorotic ring spots on three aroids were identified as isolates of KoMV for the first time from Andhra Pradesh, India.     

The DNA-1 like alphasatellites in association with the bipartite Mungbean yellow mosaic virus in natural infections

Yellow mosaic disease is the major limitation in the production of grain legumes in India. This disease is caused by bipartite begomovirus, Mungbean yellow mosaic virus. In addition to the bipartite genomic components, the yellow mosaic disease affected urdbean plants which contain satellite like DNA-1 component called as alphasatellites. The present study has been attempted to characterise the alphasatellites associated with Mungbean yellow mosaic virus. Nucleotide sequence analysis of alphasatellites showed 98% identity with Vernonia yellow vein Fijian alphasatellite, VYVFA (JF733780). Since the sequence identity is more than 98%, the threshold value for demarcation of alphasatellites species, the alphasatellites of the present study are named as Vernonia yellow vein Fijian alphasatellite. Comparison with other, alphasatellites shared 51–55% identity with alphasatellites associated with monopartite begomovirus and it shared only 41–42% identity with an unusual alphasatellites, DNA-2. This is the first report on characterisation of alphasatellites associated with Mungbean yellow mosaic virus.     

Dolichos yellow mosaic virus belongs to a distinct lineage of Old World begomoviruses; its biological and molecular properties

Dolichos yellow mosaic disease (DYMD) affects the production of dolichos in South Asia. Diseased plants produce characteristic bright yellow mosaic patches on the leaves and early infections cause reductions in yield. The putative dolichos yellow mosaic virus (DoYMV) was transmitted poorly (maximum 18.3% transmission) by the whitefly, Bemisia tabaci. DoYMV has a narrow host range and infected only Lablab purpureus and L. purpureus var. typicum out of the 36 species tested. Virus was detected using monoclonal antibodies in a triple‐antibody sandwich enzyme‐linked immunosorbent assay and by PCR. Complete DNA‐A components of DoYMV isolates from Mysore and Bangalore, South India, were sequenced, but several attempts to identify DNA‐B and DNA‐β were unsuccessful. DoYMV isolates shared DNA‐A nucleotide identities of 92.5–95.3% with previously described isolates from North India and Bangladesh. They were most similar to mungbean‐infecting begomoviruses at 61.6–64.4% of DNA‐A nucleotide identities. Phylogenetic analyses of DNA‐A sequences grouped the dolichos‐infecting and mungbean‐infecting begomoviruses into a distinct cluster away from begomoviruses infecting non‐leguminous plants in the Indian subcontinent. Antigenically, legume‐infecting begomoviruses were most similar to each other compared with non‐legume viruses. Collectively, these results indicate that legume‐infecting begomoviruses in the Indian subcontinent belonged to a distinct lineage of Old World begomoviruses.     

Association of tomato leaf curl Palampur virus with yellow mosaic disease of Armenian cucumber (Cucumis melo var. flexuoses) and wild melon (C. callosus var. agrestis) in India

Natural occurrence of yellow mosaic disease was observed on Armenian cucumber (Cucumis melo var. flexuoses) and wild melon (C. callosus var. agrestis) with disease incidences of ~36 and ~27%, respectively. Association of tomato leaf curl Palampur virus (ToLCPV) with the disease was investigated by Polymersae chain reaction (PCR) using begomovirus-specific primers. Full-length genome was amplified by rolling circle amplification (RCA) method from representative samples of C. melo and C. callosus. RCA products obtained were cloned and sequenced. Analyses of sequence data revealed the presence of full-length begomoviral genome of 2756 nucleotides with the gene arrangement of a typical begomovirus: HQ848383 (C. melo) and GU253914 (C. callosus). Both the isolates shared 99% sequence identity together and high 97–99% identities and the closest phylogenetic relationships with ToLCPV strains reported worldwide, hence identified as two new members of ToLCPV. Natural occurrence of ToLCPV on C. melo and C. callosus is the first report.     

Host range, vector relationships and sequence comparison of a begomovirus infecting hibiscus in India

Hibiscus leaf curl disease (HLCuD) occurs widely in India. Infected hibiscus plants show vein thickening, upward curling of leaves and enations on the abaxial leaf surface, reduction in leaf size and stunting. The commonly‐occurring weeds (Ageratum conyzoides, Croton bonplandianum and Euphorbia geniculata), Nicotiana benthamiana, Nicotiana glutinosa and Nicotiana tabacum (var. Samsun, Xanthi), cotton and tomato were shown to be susceptible to HLCuD. One of the four species of hibiscus (Hibiscus rosa‐sinensis) and 75 of the 101 commercial hybrids/varieties grown in the Bangalore area of southern India were also susceptible. Two virus isolates associated with HLCuD from Bangalore, South India (Ban), and Bhubaneswar, North India (Bhu), were detected serologically and by PCR‐mediated amplification of virus genomes. The isolates were characterised by sequencing a fragment of DNA‐A component (1288 nucleotides) and an associated satellite DNA molecule of 682 nucleotides. Phylogenetic analyses of these DNA‐A sequences clustered them with Old World cotton‐infecting begomoviruses and closest to Cotton leaf curl Multan virus (CLCuMV) at 95–97% DNA‐A nucleotide identities. The 682‐nucleotide satellite DNA molecules associated with the HLCuD samples Ban and Bhu shared 96.9% sequence identity with each other and maximum identity (93.1–93.9% over positions 158–682) with ～1350‐nucleotide DNA‐β satellite molecules associated with cotton leaf curl disease in Pakistan and India (accession nos AJ298903, AJ316038). HLCuD in India, therefore, appears to be associated with strains of CLCuMV, a cotton‐infecting begomovirus from Pakistan, which is transmitted in a persistent manner by Bemisia tabaci.     

A Leaf Curl Disease in Germplasm of Rapeseed‐Mustard in India: Molecular Evidence of a Weed‐Infecting Begomovirus–Betasatellite Complex Emerging in a New Crop

Evaluation of 130 accessions of rapeseed‐mustard germplasm grown at the National Bureau of Plant Genetic Resources, New Delhi, India during the winter season (2011–2012) revealed the occurrence of a leaf curl disease in seven accessions. The occurrence of the disease was observed in another 62 of 525 accessions evaluated during 2012–2013. The association of a monopartite begomovirus and betasatellite was established with the symptomatic plants by whitefly transmission and PCR amplification. The complete nucleotide sequences of the begomovirus (JX270684, 2745 nucleotides), obtained by rolling circle amplification, showed the highest sequence identity (98.1%) with the weed‐infecting begomovirus, Croton yellow vein mosaic virus. Analysis of recombination indicated the probable occurrence of many overlapping inter‐ and intraspecific recombination events. The sequence of betasatellite (JX270685, 1355 nucleotides) showed the highest sequence identity (95.7%) with Croton yellow vein mosaic betasatellite. Begomoviruses were not previously known to naturally infect rapeseed‐mustard. This is the first report of the emergence of a weed‐infecting begomovirus–betasatellite complex in rapeseed‐mustard germplasm in India and raises the concern on utilization of such susceptible germplasm in crop improvement programmes.     

Characterisation of pumpkin yellow vein mosaic virus from India

Yellow vein mosaic disease symptoms occur frequently in pumpkin in India. Diseased plants show vein yellowing, which sometimes coalesces to form chlorotic patches. Infected plants are stunted and flowers drop prematurely, greatly reducing yields. Diseased plants are infected by a begomovirus, designated pumpkin yellow vein mosaic virus (PYVMV), which is transmitted readily and in a persistent manner by the whitefly, Bemisia tabaci. Transmission of PYVMV requires minimum acquisition and inoculation access periods of 30 min and 10 min, respectively. The minimum latent period in the insect is 6 h and the virus persists in the vector for at least 8 days. PYVMV has a narrow host range consisting of a small number of cucurbit species and some tobacco cultivars. It was detected serologically in diseased plants and in viruliferous B. tabaci using polyclonal antibodies in a double‐antibody sandwich enzyme‐linked immunosorbent assay. Reactions with monoclonal antibodies in a triple‐antibody sandwich ELISA showed that PYVMV has an epitope profile distinct from those of other begomoviruses from the Indian sub‐continent. Polymerase chain reaction amplified fragments from the putative viral coat and movement protein genes. Based on comparative phylogeny of complete coat protein gene sequences, PYVMV was most similar to the bipartite Tomato leaf curl New Delhi virus from India and appears to be a new strain of this virus.     

Genetic diversity of legume yellow mosaic begomoviruses in Indonesia and Vietnam

High incidences of yellow mosaic symptoms were observed in soybean and yard‐long bean crops in Indonesia in 2009 and in mungbean crops in Vietnam in 2011. All five soybean and 20 yard‐long bean samples from Java, Indonesia, and 15 mungbean samples from Vietnam with symptoms tested positive for begomovirus infection by polymerase chain reaction (PCR) with primer pair PAL1v1978B/PAR1c715H. On the basis of collection location and the nucleotide sequence comparisons of the 1.5 kb begomoviral DNA‐A components amplified, a subset of samples comprising two soybean and six yard‐long bean isolates from Indonesia and five mungbean isolates from Vietnam were taken forward for more detailed examination. Sequence comparison and phylogenetic analysis of the full‐length sequences of all Indonesian and Vietnam isolates alongside other legume‐infecting begomoviruses revealed that all the isolates from Indonesia were Mungbean yellow mosaic India virus (MYMIV) strain‐A, and all from Vietnam were Mungbean yellow mosaic virus (MYMV) strain‐B. To the best of our knowledge, this is the first identification of MYMIV and MYMV associated with yellow mosaic of legumes in Indonesia and Vietnam, respectively. The epidemiological implications and potential consequences of the emergence of legume‐infecting begomoviruses on legume production in these areas of Southeast Asia are discussed.     

Antisense RNA approach targeting Rep gene of Mungbean yellow mosaic India virus to develop resistance in soybean

The Yellow mosaic disease is caused by Mungbean yellow mosaic India virus (MYMIV) and Mungbean yellow mosaic virus (MYMV) belonging to the genus Begomovirus of the family Geminiviridae. Yellow mosaic disease (YMD) is a major constraint to the production of soybean in South-East Asia. In India, yield losses of 10–88% had been reported due to YMD of soybean. An effort has been made to generate resistant soybean plants, by a construct targeting replication initiation protein (Rep) gene sequences of MYMIV. A construct containing the sequences of Rep gene (566?bp) in antisense orientation was used to transform cotyledonary node explants of three soybean cultivars (JS 335, JS 95-60 and NRC 37). Transformation efficiencies of 0.2, 0.21 and 0.24% were obtained with three soybean cultivars, JS 335, JS 95-60 and NRC 37, respectively. The presence of transgene in T₁ plants was confirmed by polymerase chain reaction (PCR) and sequence analysis. The level of resistance was observed by challenge inoculation with the virus in T₁ lines. The inheritance of transgene showed classical Mendelian pattern in six transgenic lines.     

First report of Squash leaf curl china virus causing mosaic symptoms on summer squash (Cucurbita pepo) grown in Varanasi district of India

Severe incidence of a mosaic disease was observed on summer squash (Cucurbita pepo), commonly called pepo, grown in Varanasi during June–September of Khariff season 2007. Symptoms observed were mosaic, puckering on the leaves, wartiness on fruits, general stunting of plants and low yield. PCR amplification with degenerate primers designed to target the conserved sequences of coat protein gene of whitefly transmitted geminiviruses showed ～800 bp fragment in all symptomatic samples tested, indicating the association of a geminivirus with the disease. Nucleotide sequence analysis of the amplified fragment showed 99% identity with pumpkin isolate of squash leaf curl china virus (SLCCNV) from Lucknow. It showed 85–96.7% homology with other isolates of SLCCNV from India and abroad. Phylogenetic analysis revealed the isolate on pepo from Varanasi clustered with SLCCNV isolates on pumpkin from Lucknow and Coimbatore.     

Mixed infections of begomoviruses in pumpkins with yellow vein mosaic disease in north India

Yellow vein mosaic disease of pumpkin (Cucurbita moschata) is a serious problem for the cultivation of pumpkin throughout India. Symptomatic samples collected from Varanasi region of North India showed mixed infection of the three begomoviruses which could represent up to three species namely Tomato leaf curl New Delhi virus, Squash leaf curl China virus and Tomato leaf curl Palampur virus.     

Broad-based resistance to pigeonpea sterility mosaic disease in wild relatives of pigeonpea (Cajanus: Phaseoleae)

Sterility mosaic disease (SMD), an important biotic constraint on pigeonpea (Cajanus cajan) in the Indian subcontinent, is caused by Pigeonpea sterility mosaic virus (PPSMV) transmitted by the eriophyid mite, Aceria cajani. Distinct PPSMV isolates occur in different geographical regions and broad‐based resistance to all these isolates is scarce in cultivated pigeonpea germplasm. Wild relatives of pigeonpea, which are known to possess resistance to several pests and diseases, were evaluated for broad‐based SMD resistance. One hundred and fifteen wild Cajanus accessions from six species (C. albicans, C. platycarpus, C. cajanifolius, C. lineatus, C. scarabaeoides and C. sericeus) were evaluated against three PPSMV isolates prevailing in peninsular India. Evaluations were done under greenhouse conditions in endemic locations of each isolate through mite‐mediated virus inoculation. Fifteen accessions showed resistance to all three isolates: ICP 15614, 15615, 15626, 15684, 15688, 15700, 15701, 15725, 15734, 15736, 15737, 15740, 15924, 15925 and 15926. Most of the wild accessions did not support mite multiplication. The majority of the accessions resistant to PPSMV following inoculations with viruliferous mites were susceptible by graft inoculation, suggesting that vector resistance is conferring resistance to infection with PPSMV. The 15 accessions identified as being resistant to infection to all three virus isolates tested are cross compatible with pigeonpea by traditional breeding. They are therefore useful for exploitation in breeding programmes to increase both the level of SMD resistance and to diversify its genetic base in the cultivated pigeonpea gene pool.     

Identification of Mungbean yellow mosaic Indian virus Associated with Tomato Leaf Curl Betasatellite Infecting Phaseolus vulgaris in Oman

Kidney bean (Phaseolus vulgaris) plants exhibiting foliar yellow mosaic symptoms and some leaf crumpling were identified in the Al Batinah region of Oman. Rolling circle amplification and polymerase chain reaction identified a bipartite begomovirus (family Geminiviridae) and a betasatellite in association with the symptomatic plants. Analysis of full‐length sequences showed the virus to be Mungbean yellow mosaic Indian virus (MYMIV) and the betasatellite Tomato leaf curl betasatellite (ToLCB). This is the first identification of a legume‐adapted begomovirus in Oman and the first identification of MYMIV in association with the betasatellite ToLCB. The isolate of MYMIV from Oman shows the greatest levels of sequence identity to isolates occurring in South Asia and South‐East Asia, suggesting that the virus has only recently been introduced. The significance of these findings is discussed.     

Detection of begomovirus associated with okra leaf curl disease

Leaf curl and yellow vein mosaic viral disease is the major constraint on okra (Abelmoschus esculentus L.) production in India. Amplified fragment sequence of DNA-β showed highest similarity of 91.7% with Bhendi yellow vein mosaic virus-Tamil Nadu (AJ308425, NC_003405) and lowest similarity of 48.5% with OKLCV (NC_004093), whereas coat protein specific amplified sequence showed highest homology with isolate of Madurai, Haryana, Ludhiana and lowest homology of 92% with Mesta yellow vein mosaic Bahraich virus (MYVMBV) (EU360303). The results obtained in the present study confirm that both the viral diseases of okra reported in southern India are caused by a begomovirus associated with DNA-β in which the plants show leaf curl symptoms and never develops yellow vein mosaic and those plants which show yellow vein mosaic, never develops leaf curl symptoms even in the same rows and field. The okra leaf curl is an emerging virus disease in India.     

Genetic Diversities of Cymbidium mosaic virus and Odontoglossum ringspot virus Isolates Based on the Coat Protein Genes from Orchids in Guangdong Province,China

Orchids are some of the most important ornamental flowers. Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) are the most prevalent and economically important viruses affecting orchids in China. In this study, 20 CymMV and 28 ORSV isolates were selected for genetic diversity analysis. The CymMV isolates shared 84.6–100% and 89.5–100% identities of coat protein (CP) at the nucleotide (nt) and amino acid (aa) levels, respectively. The identities of ORSV isolates were 96.4–100% (nt) and 92.5–99.4% (aa). The CP genes of CymMV were found to have genetic diversity, and the CP genes of ORSV were genetically conservative. These results can aid in designing effective disease‐control strategies.     

Characterization of Mungbean yellow mosaic India virus genome with a recombinant DNA-B in Southern Peninsular India.

Molecular Biology Reports - Mungbean yellow mosaic India virus (MYMIV) is a representative of the genus begomovirus/Begomoviridae, which is prevalent in the northern part of Indian subcontinent...