Floriculture Division, Institute of Himalayan Bio-resource Technology, Palampur-176061, Himachal Pradesh.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Diseases caused by plant viruses are a major concern to floricultural crops. To combat viral diseases it is important to diagnose the viruses efficiently and effectively. Advances in serological and biotechnological techniques have evolved immensely leading to reliable detection of these pathogens. Serological detection apart from other tests has greatly improved with the advent of ELISA using polyclonal as well as monoclonal antibodies. At IHBT a number of viruses have been detected from floricultural crops using polyclonal antibodies by ELISA namely Dasheen mosaic (DsMV), Alstroemeria carlavirus, Alstroemeria mosaic (AlMV), Cucumber mosaic (CMV) (alstroemeria, chrysanthemum, gerbera, gladiolus and lily strains), Tospovirus (alstroemeria, begonia, chrysanthemum, gladiolus and lily strains) Carnation etched ring (CERV), Carnation mottle (CarMV), Carnation vein mottle (CVMV), Carnation latent (CLV), Carnation necrotic fleck (CNFV), Carnation ringspot (CRSV), Tomato aspermy (TAV), Chrysanthemum B (CVB), Bean yellow mosaic (BYMV) (gladiolus and iris strains), Tobacco mosaic (TMV) (gladiolus and rose strains), Tobacco rattle (TRV), Tobacco ring spot (TRSV), Iris mild mosaic (IMMV), Iris severe mosaic (ISMV), Lily mottle (LMoV) Lily symptomless (LSV), Tulip breaking (TBV), Strawberry latent ringspot (SLRSV) (lily and rose strains), Apple mosaic (ApMV), Arabis mosaic (ArMV), Prunus necrotic ring spot (PNRSV) rose strain, Cymbidium mosaic (CymMV) and Odontoglossum ring spot (ORSV) viruses. Immunosorbent electron microscopy (ISEM) is also an effective tool to diagnose the viruses. Using this technique a number of viruses namely DsMV, TAV, CMV (alstroemeria, chrysanthemum, gerbera, gladiolus and lily strains), CVB, BYMV (gladiolus and iris strain), IMMV, ISMV, LMoV, LSV, TBV, CymMV and ORSV have been identified infecting floricultural crops at IHBT. Polyclonal antibodies to be used at large scale and for continuous availability, have been developed in rabbit using expressed coat protein gene in E. coli against CMV, CarMV, CERV, CymMV, LSV, PNRSV and TAV.
Polymerase chain reaction (PCR) has been exploited for the detection of plant viruses and presently this is a common technique for plant virus detection. Reverse Transcription PCR (RT-PCR)/PCR techniques have been standardized at IHBT to detect Alstroemeria carlavirus, Tospovirus (alstroemria strain), AlMV, CMV (alstroemeria, chrysanthemum, gerbera, gladiolus, lily strain), PNRSV (begonia gladiolus and rose strains), CERV, CarMV (carnation and begonia strains), CVMV, CNFV, TAV, CVB, BYMV (gladiolus and iris strains), IMMV, ISMV, LMoV, LSV, TBV, CymMV and ORSV. For most of the viruses the primers were designed indigenously. Complete genome of Chrysanthemum stunt viroid (CSVd) has also been amplified by RT-PCR. Various kinds of PCR have been developed namely immunocapture (IC) RT-PCR) for IMMV, ISMV, BYMV, ArMV and CarMV. Multiplex-PCR has been standardized to detect CERV (three genes viz. coat protein, movement protein and aphid transmitting) and TAV (RNA1, RNA2 and RNA3). Nucleic acid hybridization using DNA/RNA and a complementary nucleic acid probe is also an important technique to detect the viruses in a large number of samples. This technique has been utilized to detect CMV (alstroemeria, chrysanthemum, gerbera, gladiolus, lily), CERV, CarMV, CVMV, CNFV, TAV, CVB, BYMV (gladiolus and iris), IMMV, ISMV, LMoV, LSV, TBV, PNRSV (rose), CymMV, ORSV and for CSVd. RT-PCR has also been standardized for the detection of ArMV and SLRSV in their nematode vectors viz. Xiphinema spp. and Longidorus spp. infecting lily and rose crops.
In vitro techniques have been standardized to produce virus-tested ornamental crops like alstroemeria, begonia, carnation, chrysanthemum, gerbera, gladiolus and lily. The planting materials are being generated and provided to the growers. Farmers and NGO's are being trained towards production and maintenance of virus-free quality planting material.
