Evidence for association of southern rice black-streaked dwarf virus with the recently emerged stunting disease of rice in North-West India

The concurrent reports on emergence of stunting disease of rice across the North-west Indian rice growing areas attracted attention for elucidating its etiology. Surveys of different rice fields recorded an incidence of stunting disease in the range of 1-20% in the affected fields. A systematic investigation employing three independent methods was undertaken. Under electron microscope, icosahedral virions of similar to 65-75 nm were observed. Based on the shape and size of virion particles and symptoms of the disease, reverse transcription-PCR and quantitative-RT-PCR of stunted rice plants and prevalent white-backed planthopper (WBPH) were performed using specific primers targeting two genomic components (S9 and S10) of Southern rice black-streaked dwarf virus (SRBSDV), a double stranded RNA virus of genus Fijivirus and the results indicated its specific association with stunting disease of rice. Sequencing of the amplified S9 and S10 genomic components showed maximum identity of 97.90-100.00% and 98.04-99.48%, respectively with SRBSDV isolates from South Korea and Vietnam. To the best of our knowledge, this is the first conclusive evidence of association of SRBSDV with stunting disease of rice from India. The findings seek urgent attention and in-depth investigation on its establishment in the Indian subcontinent and necessary interventions.