A critical appraisal of challenges in exclusion of plant viruses during transboundary movement of seeds

With the liberalization of trade under the WTO regime the possible introduction of plant viruses has increased and so are the challenges to contain them. There is a need to carryout pest risk analysis prior to import of planting material. Availability of virus detection techniques, sample size, sampling procedures, detecting an unknown/ exotic virus, post-entry quarantine, urgency in clearance of the sample, antisera bank for exotic viruses and a database on sequences of virus-specific primers, easy to use PCR-based techniques including multiplex PCR are the challenging areas that need attention for exclusion of plant viruses. Development of strategies for detection of several viruses simultaneously on DNA arrays has to be explored. Adopting a workable strategy, a number of exotic viruses have so far been intercepted in imported germplasm, which includes the one not yet reported from India and also not known to occur on particular host(s).