Résumé
Diseases caused by plant viruses can have significant and devastating impacts on many cultivated crops worldwide. The impact of disease caused by a virus depends on the virus species, strains, type of inoculum, host plant characteristics, vector pressure, climatic conditions, trade, changes in agricultural landscape and intensive production practices. Viruses affect plants by causing a large variety of symptoms such as alteration of shape, pigmentation, necrosis on different parts of the plant, thus affecting plant development. In most of the cases, these lead to a decrease in crop yield and quality. There are numerous viruses that affect potato; among them, Potato virus Y is considered to be one of the ten most important plant viruses of crops, because of its worldwide distribution and economic impact. Some PVY isolates are able to cause potato ringspot necrotic disease in infected tubers rendering them unmarketable. Understanding the genetic diversity and molecular biology of PVY is essential to understand its infectious cycle, epidemiology and developing efficient methods of control and management for the virus itself and its vector. In spite of an ever-increasing wealth of data in these topics, several major scientific challenges remain in understanding the molecular nature of the interaction between PVY, its hosts, aphid vector in different environments and the epidemiology of PVY. This and following chapters will present the context and current state of our knowledge for these different topics and attempt to provide some answers to these important questions.