The Role of the Helper Virus in Aphid Transmission of Potato Aucuba Mosaic Virus and Potato Virus C

Abstract

SUMMARYPotato aucuba mosaic virus and potato virus C were transmitted by the aphid Myzuspersicae, not only from plants also infected with a helper virus, but also from plants infected with them alone, provided the aphids fed first on plants infected with the helper virus. Several different viruses acted as helpers but all are in the potato virus Y group. Helper viruses differed in the efficiency with which they aided potato aucuba mosaic virus and potato virus C, and some potato aucuba mosaic virus isolates were transmitted more frequently than others. With potato virus Y as helper, up to 3o % of the aphids transmitted potato aucuba mosaic virus. Aphids were usually fed for brief periods on plants infected with the helper virus but aphids fed for 2 days also transmitted potato aucuba mosaic virus readily. Starving the aphids for I to 2 hr between their acquisition feeds on plants infected with helper and aided virus decreased but did not eliminate transmission.

Mutations in the HC-Pro gene of zucchini yellow mosaic potyvirus: effects on aphid transmission and binding to purified virions.

“…The first report of the presence of helper activity in plants infected with a potyvirus was of a strain of potato virus Y (PVY c ) (Kassanis & Govier, 1971). Using membrane feeding, evidence was then provided that the so-called ' helper ' is a component other than the virion .…”

Mutations in zucchini yellow mosaic virus helper component protein associated with loss of aphid transmissibility

“…Loss of transmissibility associated with HC deficiency was also reported (Kassanis & Govier, 1971 ;Thornbury et at., 1990;Lecoq et al, 1991) both for ZYMV isolates and potato virus C (PVC). Thornbury et al (1990) identified two mutations in the HC coding sequence of PVC potentially leading to the loss of aphid transmissibility.…”

Loss of Aphid Transmissibility of Plum Pox Virus Isolates

“…The presence of a DAG motif in the CP of an aphid transmissible isolate of PPV and its absence in a non-aphid transmissible one was reported by (25). In other reports, the lack of aphid transmission of certain potyviruses has been associated with lack of a helper component in infected tissues or with the presence of a defective one (16,17,21,23).…”

“…The successful transmission of potyviruses also depends upon an active HC. The requirement of an HC in the transmission of potyviruses was recognised by ( 14) and ( 16,17). The HCs of several potyviruses, including these of Potato virus Y 0 , TEV and TVMV have been extracted and purified (9,32,36,37).…”