Coated-Vesicle Transport of Luteoviruses Through Salivary Glands ofMyzus persicae

Abstract

Beet western yellows virus (BWYV) or potato leaf roll virus (PLRV) was visualized by EM in basal lamina and plasmalemma invaginations of accessory salivary glands in each of 61 aphids that had fed on infected plants [Raphanus sativus L. cv. White Icicle], but never in any of 15 control aphids reared on healthy plants. Virions were identified as BWYV or PLRV by indirect labeling with ferritin-antibody. Virus particles were frequently observed in tubular vesicles and coated vesicles in cytoplasm near salivary canals and in coated pits connected to the canal membrane. Following injection of anti-PLRV antibody into the aphid hemocoel, PLRV particles accumulated in the accessory gland basal lamina and aggregated in the salivary duct. These results help identify the route of luteoviruses through the accessory salivary gland to the salivary duct. A cellular mechanism, involving coated-vesicle transport of virions from tubular vesicles to the salivary canal, is suggested as a model for transport of luteovirus through accessory gland cytoplasm. The relation of vector-specific transmission of luteoviruses to this model is discussed.