Plant Virus Transmission by Insects

Abstract

Most plant viruses depend on vectors for their survival and spread. Most vectors are piercing-sucking insects that transmit plant viruses in either the circulative virus (CV) or noncirculative virus (NCV). NCV are carried on the lining cuticle of vectors stylets. CVs cross the vectors’ gut, move internally to the salivary glands (SG), cross the SG membranes to be ejected upon feeding. Transmissibility of NCVs depends on motifs of coat protein and for Potyviruses and Caulimoviruses also on helper proteins (encoded by the virus). NCV proteins were found to associate with vectors’ cuticle proteins. Transmissibility of CVs depends on proteins comprising the virus capsid (the coat protein and the read-through protein) and on symbionin (produced by vectors’ symbionts). Passage of CV through the gut has been also associated with vectors’ proteins. To suppress plant virus epidemics, several control measures that interfere with vector landing or feeding are proposed.