Central Potato Research Institute, Shimla-171001, India.
Potato (Solanum tuberosum L.), a member of the family Solanaceae, is perhaps the best example of a crop plant to which biotechnology has been most extensively applied in all aspects of production, germplasm handling and genetic improvement. Potato is a vegetatively propagated crop, which is a good host to a large number of viruses besides other pathogens. Disease free planting material, therefore, constitutes a key component of the integrated disease management (IDM) schedule of potato. Tissue culture techniques like meristem tip culture and micropropagation have been perfected by the institute that are being used routinely for production of virus free planting materials. ELISA is being used as the primary protocol for potato virus detection in seed production. Nucleic acid spot hybridization (NASH) technique is now routinely being used for detection of potato spindle tuber viroid (PSTVd), PVS, PVX, PVY and PLRV. RT-PCR based detection of the above four viruses has been achieved and validated for routine use in post-entry quarantine, screening of mericlones and in vitro microplants for virus freedom.
Though potato is infected by over 30 viruses and virus-like agents, potato virus Y (PVY), potato leaf roll virus (PLRV) and the newly emerging potato apical leaf curl virus caused by ToLCNDV are the important viruses that cannot be managed by conventional breeding. Transgenic development by using pathogen-derived resistance is, therefore, being pursued for their management. Attempts were made to develop PVY resistant potato by using the CP gene in collaboration with Bhabha Atomic Research Centre (BARC) and Advanced Centre on Plant Virology, IARI. Seventeen putative PLRV CP-transgenic lines of Kufri Bahar and Kufri Pukhraj were developed. Presence of PLRV CP gene was confirmed by PCR in 2 lines of K. Pukhraj. Sense, antisense and hairpin constructs of the rep gene ToLCNDV have been cloned in the binary plnat transformation vector, which are being used for transgenic development. Marker assisted selection (MAS) is particularly useful in case of introgression breeding where one or a few useful genes from an otherwise undesirable wild background have to be transferred to a commercial cultivar. Tightly linked markers for many qualitative and quantitative traits of potato have been published and are available for MAS. A published SCAR marker tightly linked to extreme resistance to PVY has been validated at CPRI and is now being used for development of triplex/quadruplex parental line and for breeding potato varieties with combined resistance to PVY and late blight.
