Division of Plant Quarantine, NBPGR, Pusa Campus, New Delhi
National Symposium on “Plant Pathology in the Changing Global Scenario” held at National Bureau of Plant Genetic Resources, New Delhi on February 27–28, 2009
More than 130 viruses are seed-borne and seed-transmitted in plants and may also spread by vectors in fields causing severe crop losses. This calls for a stringent quarantine processing of imported seeds. Adopting a strategy of post-entry quarantine and laboratory testing using infectivity assay, electron microscopy, enzyme-linked immunosorbent assay, dot immunobinding assay and reverse-transcription polymerase chain reaction, a number of exotic viruses have been intercepted in germplasm imported into India for the last 10 years. The interception includes the destructive viruses yet not reported from India viz., Broad bean stain virus on Vicia faba, Cherry leaf roll virus on Glycine max and Phaseolus vulgaris; Cowpea mottle virus on Vigna subterranea, Raspberry ringspot virus and Tomato ringspot virus on G. max. Besides, ten viruses viz., Alfalfa mosaic virus, Bean common mosaic virus, Cowpea aphid borne mosaic virus, Cowpea mosaic virus, Grapevine fan leaf virus, Pea seed-borne mosaic virus, Southern bean mosaic virus, Soybean mosaic virus, Tobacco streak virus and Tomato black ring virus are not known to occur on the hosts in India on which they were intercepted. Even though many of the intercepted viruses are not known to occur in India, their potential vectors exist and so also the congenial conditions for them to multiply, disseminate and spread the destructive exotic viruses/strains and even native strains more efficiently. The present scenario of global exchange of seed and liberalization in trade under WTO regime has potential in enhancing the long-distance dissemination of a destructive virus or its virulent strain, and an effective quarantine strategy for germplasm and legume seed imports is thus indispensable.
