Molecular studies on tobacco streak virus (TSV) infecting cotton in Tamil Nadu, India.

Tobacco streak virus (TSV), the causal agent of cotton necrosis, is of emerging importance in the recent years. Unfortunately, all the cotton varieties and hybrids are susceptible to this virus. Cotton plants cultivated in different districts of Tamil Nadu were surveyed during 2014–2016. Samples collected from different locations confirmed the presence of TSV in cotton. TSV infection was confirmed by direct antigen coating-enzyme linked immuno sorbent assay (DAC-ELISA), dot immuno binding assay (DIBA), and reverse transcriptase polymerase chain reaction (RT-PCR). The virus was morphologically confirmed by transmission electron microscope (TEM). TSV isolate collected from Coimbatore was sequenced to obtain the full-length genome. Full length analysis was done for RNA 1 and RNA 3, whereas there was problem in obtaining few nucleotides in 5′ and 3′ end in spite of using different primers. Critical domain search in the nucleotide sequences revealed the presence of characteristic viral methyl transferase domain and helicase domain (RNA 1), ‘GDD’ motif and ‘DFSKFD’ of viral replicase in RNA 2 and Zinc finger motif in RNA 3. Phylogenetic analysis reveals high nucleotide similarity with TSV isolates of India and USA. [ABSTRACT FROM AUTHOR]