Diagnosis of plant virus diseases

Abstract Diagnostics has played an important role in our understanding of the evolution of viruses and the emergence of viral diseases. We have come a long way from the era of filterable viruses to viromes. This chapter briefly traces the development of techniques and their application in the diagnosis of plant virus diseases. Since the demonstration of the utility of serology in plant virus diagnosis in the late 1920s, serodiagnosis has been extensively used for research, field diagnosis, seed and planting material certification programs, and plant quarantine. Introduction of the highly sensitive enzyme-linked immunosorbent assay (ELISA) in the late 1970s gave a big push to serodiagnosis of plant virus diseases. The ability of synthetically produced affirmer proteins to specifically react with homologous antigen in ELISA-based tests is going to further strengthen serodiagnostic systems in the coming years. Serology and electron microscopy remained the key diagnostic systems until the development of nucleodiagnosis in the mid-1980s. In recent years, multiplex polymerase chain reaction has emerged as the most preferred diagnostic system. Microarray and next-generation sequencing are the ultimate nucleodiagnostic systems to detect known and discover unknown viral infections, as well as generating information on viral sequences derived from metagenomics sequence data.