The transmission of plant viruses

Plant viruses are a threat to a sustainable economy because they cause economic losses in yields. The epidemiology of plant viruses is of particular interest because of their dynamic spread by insect vectors and their transmission by seeds. The speed and direction of viral evolution are determined by the selective environment in which they are found. Knowledge of the ecology of plant viruses is critical to the transmission of many plant viruses. Accurate and timely detection of plant viruses is an essential part of their control. Rapid climate change and the globalization of trade through free trade agreements encourage the transmission of vectors and viruses from country to country. Another factor affecting the emergence of viruses is the cultivation of monocultures with low genetic diversity a nd high plant density. Trade in plant material (germplasm and living plants) also cause the emergence of new viruses. Viruses have a fast adaptation and development in a new environment. Aphids are the most widespread and important vectors of plant viruses. Myzus persicae transmits more than 100 different plant viruses. In nature plant viruses are transmitted also by nematodes, fungi, mites, leafhoppers, whiteflies, beetles, and planthoppers. The symptoms of viral diseases are very diverse and are often confused with symptoms of abiotic stress. Control of viral diseases is based on two strategies: i) immunization (genetic resistance acquired by plant transformation, breeding, or cross-protection), ii) prophylaxis to limit viruses (removal of infected plants and control of their vectors). For management, we rely on quick and accurate identification of the disease.