Molecular approaches towards analyzing the viruses infecting maize (Zea mays L.)

Abstract

Information on virus diseases of maize still remains scanty in several maize growing countries. Therefore it is hoped that this description will stimulate more research, which will lead to better understanding of viruses infecting maize in Africa. Plant viruses are a major yield-reducing factor for field and horticultural crops. The losses caused by plant viruses are greater in the tropics and subtropics, which provide ideal conditions for the perpetuation of both the viruses and their insect vectors. Management of viral diseases is more difficult than that of diseases caused by other pathogens as viral diseases have a complex disease cycle, efficient vector transmission and no effective viricide is available. Traditionally, integration of various approaches like the avoidance of sources of infection, control of vectors, cultural practices and use of resistant host plants have been employed for the management of viral diseases of plants. All these approaches are important, but most practical approach is the understanding of seed transmission, symptom development, cell-to-cell movement and virus multiplication and accurate diagnosis of viruses. This update aims to continue on this course while simultaneously introducing additional levels of complexity in the form of microbes that infect plants. Rather than serving as a standard literature review, the objective is to provide a broad conceptual introduction to the field of molecular plant-microbe interactions, virus multiplication, transmission and virus diagnosis and various immunodiagnostic and molecular diagnostic methods such as enzymes linked immunosorbent assay (ELISA), immunosorbent electron microscopy (ISEM), polymerase chain reaction (PCR), nucleic acid hybridization, dot immunoblotting assay (DTBIA) found suitable for diagnosis of viruses infecting maize. These techniques do not only provide information for epidemiological purposes, but also help to develop disease free stock of maize. Therefore, these various techniques with symptoms and history are of immense value to diagnose maize viruses and are the cornerstone of the management of maize viruses. This information will be useful to researchers in understanding of maize viruses. Information on symptomatology, transmission, geographical distribution and properties of viruses is summarized here based on literature review. Key words: Maize, diagnosis, ELISA, transmission, virus