The Use of Nicotiana benthamiana as an Herbaceous Receptor Host for Closteroviruses From Leafroll-Affected Grapevines

Abstract

In vitro shoot tip cultures from four leafroll-affected grapevines, Vitis vinifera Limberger, Kadarka, Müller-Thurgau, and Schwarz Riesling, were ground in a nicotine-containing buffer, and the extracts were rubinoculated into Nicotiana benthamiana. The N. benthamiana plants inoculated with extracts from the first two cultivars showed an auxiliary vein clearing which eventually progressed into an interveinal chlorosis with darker primary vein banding. Only one type of closterovirus, identified by immunosorbent electron microscopy (ISEM) as grapevine virus A (GVA), was detected in these plants. The N. benthamiana plants inoculated with extracts from Müller-Thurgau or Schwarz Riesling showed a flecking which developed into a pronounced interveinal chlorosis with dark vein banding. These N. benthamiana plants contained two types of closterovirus-like particles. One type was identified as GVA by ISEM. The other closteroviruslike particles were not decorated in ISEM preparations using antisera prepared against the closteroviruses GVA, NY-1, GLRV-1, or GLRV-3. These results illustrate that other closterovirus-like particles, as well as GVA, can be mechanically transmitted from grapevine into N. benthamiana and are consistent with the view that grapevine leafroll disease has a complex etiology.