ABSTRACT

Plant viruses are deceptively simple in their structure and incredibly small. However, this simplicity leads to an intensely interactive relationship and dependency between virus, host, and vector. Comprehending the mechanisms unique to this relationship is vital to understand plant viral diseases. During the past 30 years, our understanding of plant viruses, how they function, and why they cause disease has exceeded the limits imagined by early virologists. Today, new plant viruses are identified rapidly and our awareness of the pathological impact caused by known and newly emerging viruses continues to increase. This impact affects producers and consumers most clearly through economic losses caused by the reduction of yield or quality, adversely affecting plant growth and reproduction, death of host tissues and plants, sterility, crop failure, increased susceptibility to other stresses, loss of aesthetic value, quarantine or eradication of infected plants, and the cost of control and detection programs (Waterworth and Hadidi, 1998).