Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/12/2006
Publication Date: 4/3/2007
Citation: Tzanetakis, I.E., Postman, J.D., Martin, R.R. 2007. First report of Blackberry chlorotic ringspot virus in Rubus in the United States. Plant Disease. 91(4):463. Interpretive Summary: In 2005, a new virus was identified in rose from Arkansas and during preparation of the results for publication the same virus was reported in blackberry from Scotland. In an effort to determine if Blackberry chlorotic ringspot virus occurs in Rubus in North America, part of the Rubus and Fragaria collection at the National Clonal Germplasm Repository in Corvallis was screened for the presence of this virus. Two of 30 Rubus plants tested were found to be infected with the virus, but none of 18 strawberry plants tested were infected when tested by RT-PCR. Based on sequences of ~500 base PCR products, the two isolates of the virus from the NCGR were very similar to each other and closely related to the isolate from rose in Arkansas. The diagnostic test developed for this virus can be used for certification and quarantine purposes.
Technical Abstract: Blackberry chlorotic ringspot virus (BCRV), genus Ilarvirus, has been found in Rubus in Scotland and rose in the United States. The possibility that BCRV infects other hosts in the United States was explored. We tested 18 Fragaria and 30 Rubus accessions from the National Clonal Germplasm Repository in Corvallis, OR. These plants have tested positive for an ilarvirus using molecular or immunological tests or have given ilarvirus-type symptoms on indicator plants. The plants were tested using reverse transcription polymerase chain reaction (RT-PCR) with primers F (5'-GTTTCCTGTGCTCCTCA-3') and R (5'-GTCACACCGAGGTACT-3') that amplify a 519-522 (depending on the isolate) bases region of RNA 3 of the virus. Two black raspberry accessions, RUB 433 and RUB 9012 tested positive for the virus. These isolates (Genbank accession No EF041817 and EF041818 for RUB 433 and 9012, respectively) had 97% nucleotide sequence identity to each other and 95% and 88% nucleotide identity to the rose and Scottish isolates, respectively. Chenopodium quinoa plants inoculated with isolate RUB 433 developed mild chlorotic spots on the inoculated leaves four days post inoculation. RT-PCR and sequencing of the amplicons verified BCRV infection on C. quinoa. This is the first report of BCRV infecting Rubus outside the United Kingdom.