Viruses are considered to be the the most difficult plant pathogens to diagnose. Rapid development in characterizing viruses during the last three decades has led to improved virus detection and identification. A wide spectrum of immuno- and nucleo-based assays such as enzyme-linked immunosorbent assay (ELISA), immuno electron microscopy (IEM), nucleic acid spot hybridisation (NASH), polymerase chain reaction (PCR), reverse transcription (RT)-PCR, immunocapture (IC)-RT-PCR, multiplex PCR, real time PCR, and microarray technology have been developed for rapid and reliable detection of plant viruses. These single/multi target assays have already gained acceptance in applications ranging from generation of virus free planting material to quarantine interceptions during the movement of planting material and germplasm exchange across the domestic and international boundaries and assessment of biodiversity. Of these, ELISA and PCR based assays are currently in use in several diagnostic laboratories on a day-to-day basis. Molecular diagnosis of Tospo- and Ilar-viruses, fast emerging as serious pathogens of the field and horticultural crops in India, will be discussed.
