Molecular cloning of Indian tomato leaf curl vims genome following a simple method of concentrating the supercoiled replicative form of viral DNA (original) (raw)
Related papers
Significant Acheivements and Current Status : Virology
Adolf Eduard Mayer in 1880s for the first time thought that mosaic symptoms in tobacco termed by the Dutch growers as “bunt”, “rust” or “smut” is distinct therefore; to prevent confusion he termed it “mosaic disease of tobacco”. Thus the first ever name of a viral disease was inadvertently coined. ‘Virus’ (venom/poison) a Latin word was first used for the causal agent of this disease when Martinus Beijerinck gave the classical ‘contagium vivum fluidum’ theory in 1898. Since then several landmark discoveries viz. insect, nematode, fungus, dodder and seed transmission of viruses; local lesion host used for quantitative assay of tobacco mosaic and other viruses; antigenicity and immunogenicity; nucleoprotein nature; isolation, purification and electron microscopy; inclusion bodies; infectivity by nucleic acid; viroids; satellite virus; nanovirus; DNA 1 and DNA β etc. coupled with the recent advancements in molecular studies lead to the development of strong system of classification of viruses. Today Virology is a separate dynamic science. In the recent years, developments were so fast that now there are as many as 15 journals exclusively devoted to the science of Virology. In India root (wilt) disease of coconut (Cocos nucifera L.) is known to be present since 1882 (Table 1) in south Kerala (Butler, 1908, Varghese, 1934, Nampoothiri and Koshy, 1998). Thereafter, almost simultaneous to ‘contagium vivum fluidum’ theory (1898), spike disease of sandal (Santalum album L.), was observed in Karnataka in 1899 (McCarthy, 1903). However the long understood viral etiology of these diseases proved to be elusive when Solomon et al. (1983) and Varma et al. (1969) respectively reported association of mycoplasma like organisms (MLOs) later termed as phytoplasma with these diseases. Thus the first virus disease studied in India became mosaic of sugarcane reported by Dastur in 1923. There after several other virus diseases (Table-1) were recorded in the country. Upto mid fifties about 70 plant virus diseases were recorded infecting 59 plant species in19 families (John. 1957). When Dastur in 1923 noticed sugarcane mosaic in Bihar, it was very much dreaded because then recently in 1920 it caused epiphytotics in Louisiana, USA resulting into near collapse of the sugar industry there (Abbot, 1961). In this furore, for the first time in India detailed studies were undertaken on any plant virus disease (McRae, 1926, McRae, 1932, McRae and Subramaniam, 1928, McRae and Subramaniam, 1933, McRae and Subramaniam, 1934, Rafay, 1935, Chona and Rafay, 1950). Some important findings of these studies were; that sugarcane mosaic disease was wide spread in India, it induced 10% reduction in yield, it did not affect the quality of the juice and sugarcane varieties in India were tolerant to this disease. It was later reported that losses due to this disease were much higher (Rishi et al., 1975) and also there was deterioration in the quality of juice (Bhargava, 1971). For the first time in India internationally accepted sugarcane differentials were used and several strains of this virus were identified (Rishi, 1969, Bhargava, et al., 1972, Bhargava, 1971, 1975, Rao et al., 2002).
Journal of Phytopathology, 1989
Tomato yellow leaf curl virus (TYLCV) DNA was used as a probe to identify and analyze virus-related DNAs in the viral capside, in infected tomato plants and in the virus vector, the whitefly. In addition to the single-stranded viral genomic DNA, double-stranded virus-related DNA molecules were detected in infected plants. Not all of the virus-related DNA forms are present simultaneously in the infected plant. The double-stranded molecules, which are probably the replicative form of the viral genome, have been purified from an infected tomato plant. In the viruliferous whitefly, only the single-stranded unit-size viral genome was detected.
Reverse transcription polymerase chain reaction of the infected leaf samples of Colocasia esculenta plants showing severe whitish feathery symptoms were carried out using Potyvirus group specific primers, resulting in an amplicon of 327 bp, encoding the core region of the coat protein gene. Sequencing and BLAST analysis showed that the virus is distinct, closely related to Dasheen mosaic virus (DsMV). Sequence analysis revealed 86 and 96% identity at the nucleotide and amino acid level respectively with the DsMV isolate SY1(accession Number AJ628756). This is the first molecular level characterisation of the DsMV infecting C. esculenta in India.
European journal of plant pathology, 1998
DNA of tomato yellow leaf curl virus (TYLCV), a geminivirus transmitted by the whitefly Bemisia tabaci, was amplified from squashes of infected tomato plants and of viruliferous vectors using the polymerase chain reaction (PCR). Samples of infected tissues as small as 1 mm 2 were squashed onto a nylon membrane. A 1 2 mm strip containing the squash was introduced into a 25 l PCR reaction mix. The reaction products were subjected to gel electrophoresis, blotted and hybridized with a radiolabeled virus-specific DNA probe. TYLCV DNA was amplified from squashes of leaves, roots, and stem of infected tomato and from individual viruliferous whiteflies. The same squash could be used several times to amplify different virus DNA fragments with various sets of primers. Thus plant and insect squashes can be used as templates for the amplification of geminiviral DNA with no need to prepare tissue extracts or purify nucleic acids. The squash-PCR procedure was applied to study whitefly transmission of TYLCV. Tomato plants were inoculated by placing a single viruliferous insect in the center of a young leaflet. In some plants TYLCV DNA was detected at the site of inoculation as early as 5 min after the beginning of the access feeding and in all plants after 30 min. The squash-PCR procedure also was applied to the study of TYLCV acquisition by the insect vector. TYLCV DNA was detected in the head of whiteflies as early as 5 min after the beginning of the access feeding on infected tomato plants. Viral DNA was detected in the thorax after 10 min and in the abdomen after 25 min.
A Century of Plant Virology in India
2017
Plant viruses are important constraints in Indian Agriculture. There are as many as 168 plant virus species documented in India. The viruses belonging to the genera, Babuvirus, Badnavirus, Begomovirus, Closterovirus, Cucumovirus, Emaravirus, Ilarvirus, Luteovirus, Macluravirus, Polerovirus, Potyvirus and Tospovirus, are economically important. The insects, aphid, thrips and whitefly are the important vectors in India. Virus diseases are more problematic in vegetable pulse and fiber crops. The investigation of plant viruses began in India a few years after the discovery of virus. Plant Virology in India has a long and remarkable history. In this book, we bring out the research findings on plant viruses that were carried out in India during the past more than 100 years. The book contains 31 chapters of which 20 are dealt with the characterization of the viruses belonging to 22 genera, one chapter is on viroids, three chapters are on virus vectors, two on diagnosis and four on manageme...