ARS | Publication request: Strawberry chlorotic fleck: Identification and Characterization of a Novel Closterovirus Associated with the Disease

Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2006
Publication Date: March 1, 2007
Citation: Tzanetakis, I.E., Martin, R.R. 2007. Strawberry chlorotic fleck: Identification and characterization of a novel Closterovirus associated with the disease. Virus Research. 124:88-94.

Interpretive Summary: Recent work on strawberry decline has shown that there are a number of virus combinations that can lead to serious decline in the field. Thus, an effort to develop diagnostic reagents for all known strawberry viruses has been undertaken. A plant maintained at the Germplasm Repository in Corvallis, OR that originally came from a collection of Dr. Fraser and labeled as Strawberry chlorotic fleck was used as a source of virus for this study. This plant was infected with Strawberry pallidosis, Beet pseudo yellows and a third crinivirus as well as with a closterovirus. Criniviruses are whitefly transmitted and closteroviruses are aphid transmitted. Since the chlorotic fleck agent has been reported to be aphid transmitted, the closterovirus is the best candidate as the causal agent of the disease. Double-sranded RNA was isolated, cloned and sequenced from the infected plant. Sequence information was used to develop a detection protocol for the virus, and using this test the virus was identified in several production fields.

Technical Abstract: Chlorotic fleck, a strawberry disease caused by a graft and aphid transmissible agent, was identified more than 45 years ago. The mode of transmission indicated that a virus may be associated with the disease. Four closteroviruses, two of which are novel, were identified in the single chlorotic fleck infected strawberry clone known to exist in the United States. Sequence analysis revealed a close relationship of one of the novel viruses with members of the Closterovirus genus, the aphid-transmitted viruses in the family Closteroviridae. The presence of a closterovirus is in accordance with the aphid transmissibility of the chlorotic fleck agent. The genome of the virus exceeds 17 kilobases and encodes the signature closterovirus genes as well as a novel gene without obvious homologs in the family. Detection protocols have been developed and the virus was detected in several strawberry plants from production fields.