Vol. 5 No. 1
Present status of rice tungro disease in West Bengal: occurrence and characterization of viruses.
Abstract: Rice tungro disease is one of the most severe virus diseases of rice (Oryza sativa L.) and significant threat to rice production in Southeast Asia. In India, it can cause an estimated loss of 2% at the national level. Rice tungro is a composite disease caused by joint infection of two unrelated viruses, rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV), appears in the form of severe yellowing and stunting in susceptible rice cultivars. Exhaustive surveys have been made to identify the locations of tungro incidence in West Bengal during 2007-2008. The samples showing tungro like symptoms were collected and checked for the presence of tungro through polymerase chain reaction (PCR) using primers specific for the tungro viruses. But all the collected samples were virus free except that collected from Rice Research Station, Chinsura, Hoogly, West Bengal. Previous studies reported all the RTBV isolates from the India as the “South Asian type”. Recently considerable variations at the genomic level have been detected within the above group. In this present experiment, attempts were taken to sequence a part of the genome of both RTBV and RTSV from West Bengal to reveal any changes that might have been occurred in these segments. These sequences have been compared with the previous reports available from NCBI. Similarity analysis of the sequenced genome of RTBV exhibited about 95% similarity with the previously reported isolate from West Bengal. Where as sequenced segment of RTSV exhibited near about 96% similarity.
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