Plant virus transmission from the insect point of view

Although much is known about the proteins and processes within the plant cell required for efficient virus transmission, up to now, little was known about the requirements and mechanisms from the insect point of view. In this issue of PNAS, Uzest et al. (1) tackle that problem and trace the receptor for the cauliflower mosaic virus (CaMV) movement protein to a protein imbedded into the chitin matrix at the tip of the stylet of the aphid vector. In terms of epidemiology, insects are the most important factors in plant virus disease. Approximately 80% of the plant viruses depend on insect vectors for transmission (other vectors can be nematodes and fungi), and the plant virus vector interactions are very specific. Thus, the recent spreading of begomoviruses throughout America might be caused by the introduction of the old world vector Bemisia tabaci. This spreading might have provided the opportunity of preexisting viruses to be transmitted to a variety of crop plants (2). Plant viruses can be transmitted by insects in various ways. These have been classified as nonpersistent, semipersistent, and persistent, depending on the length of the …