Occurrence and distribution of banana streak disease and standardization of a reliable detection procedure for routine indexing of banana streak viruses in India

• In a survey conducted during the years 2010–2013, an incidence of 20–50% was recorded for banana streak disease in different banana growing areas of India. Serological and molecular methods provided the evidence for the infection of episomal Banana streak MY virus (BSMYV) and Banana streak OL virus (BSOLV) in these field samples.
• Among the various detection tools tested, the duplex-immunocapture-PCR (D-IC-PCR) employing polyclonal antiserum with an immunocapture time of 3 h was found to be a sensitive, reliable and accurate procedure for detection of episomal banana streak viruses (BSV) infection over the direct binding-PCR (DB-PCR) and rolling circle amplification (RCA).
• Based on the present study D-IC-PCR was proposed as the most effective and suitable method for routine indexing of tissue culture plantlets at different stages in the test labs as well as for germplasm exchange at quarantine stations in India. This method was successfully validated in routine indexing for BSV infection in tissue culture plantlets as well as field samples collected from different banana orchards at different locations in India.

In a survey for banana streak disease during 2010–2013, occurrence of typical streak symptoms was recorded with an incidence of 20–50% in different banana orchards at different locations in India. Serological and molecular studies provided evidence for the presence of episomal Banana streak MY virus (BSMYV) and Banana streak OL virus (BSOLV) in the field samples collected from different banana growing regions. Various methods of virus detection for banana streak viruses (BSVs) were employed. Direct PCR and direct binding-PCR (DB-PCR) did not give accurate and confirmatory results for the presence of episomal virus infection. Rolling circle amplification (RCA) was found to be highly reliable but was time consuming and difficult to use for indexing of a large number of samples. The duplex-immunocapture-PCR (D-IC-PCR) employing polyclonal antiserum with an immunocapture time of 3 h was found to be a sensitive, reliable and accurate procedure for detection of episomal BSV infection. For definite detection of BSMYV, the widely occurring banana streak virus species in India D-IC-PCR using BSMYV specific primers and Musa specific internal primers was found to be most reliable procedure which can be used for routine indexing of tissue culture plantlets at different stages in the test labs as well as for germplasm exchange at quarantine stations. Based on the immuno- and immuno-nucleo detection procedures up to 46% of samples collected from different banana growing regions of India were found positive for BSV infection. Present study for the first time reported the widespread occurrence and distribution of BSV in India.