Groundnut bud necrosis virus (GBNV) is the most significant member of the genus Orthotospovirus occurring in the Indian subcontinent. There is hardly any effective measure to prevent GBNV in crop plants. In order to develop GBNV infection prevention procedure, we examined the effect of the direct foliar application of double-stranded RNA (dsRNA) derived from the full-length NSs gene (1,320 nucleotides) of GBNV. The bacterially expressed dsRNA to the non-structural (dsNSs) gene of GBNV was purified and delivered to plants as an aqueous suspension containing 0.01% Celite for evaluating its efficacy in preventing GBNV infection in systemic host, Nicotiana benthamiana as well as in local lesion and systemic host, cowpea cv. Pusa Komal (Vigna unguiculata). The dsNSs application and challenge-inoculation were conducted in three different combinations, where plants were challenge-inoculated with GBNV a day after, immediately, and a day before the application of dsNSs. N. benthamiana plants, which were not treated with dsRNA showed severe systemic wilting and death by 9–16 days post-inoculation (dpi). The non-treated cowpea plants exhibited many chlorotic and necrotic lesions on the cotyledonary leaves followed by systemic necrosis and death of the plants by 14–16 dpi. The dsNSs treated plants in all the combinations showed significant reduction of disease severity index in both N. benthamiana and cowpea. The treatment combination where the GBNV inoculation was conducted immediately after the dsNSs treatment was found to be the most effective treatment in preventing symptom expression. The viral RNA analysis by real time PCR also showed 20 and 12.5 fold reduction of GBNV in cowpea and N. benthamiana, respectively. Our results suggest that the foliar application of dsRNA derived from the full-length NSs gene of GBNV through Celite is successful in delivering long dsRNA leading to effective prevention of GBNV infection.

No abstract

No abstract

No abstract

Promoters are specific sequence of nucleotides present upstream of gene coding region involved in initiation and regulation of transcription. Multiple cis-acting element forms the architecture of promoter to which trans-acting nucleic binding factors bind and regulates its activity. Since 1980 genome of pararetrovirus, are being exploited for developing efficient promoters. Among all of them Cauliflower mosaic virus is the most widely used promoter for gene expression. The basic rational behind the strength of promoter lies in the sequence of cis elements and the spacer nucleotide elements between them, thereby strength of these promoter fragments can be regulated by altering these nucleotide sequences. In the present study sequence of eight putative promoters of plant pararetrovirus are retrieved from National Centre for Biotechnology Information (NCBI) website. These sequence are subjected to various bioinformatics tools comprises of Clustal W, Plant Care, Mathinspector, ModelInspector for establishing the phylogenetic similarity, to identify the quantity and quality of present cis-elements, to find the various common transcription factors binding sites and to determine the presence of module for various specific functions respectively. A range of 28.80-56.0 percentage identification was observed in phylogenetic analysis, with the greatest similarity in Mirabilis mosaic virus and Dahlia mosaic virus. A broad range of cis-elements (51), transcription factor binding site (512) was obtained and 60% observed module are in combination with DOFF motif which shows a function relevance with abiotic stress inducibility. The present study had revealed the functional significance of these elements in gene regulation of pararetrovirus genome and also gives a overall idea for designing novel synthetic promoter.