Characterization of cucumber mosaic virus originating from cucurbits in Serbia

Cucumber mosaic virus (CMV) is considered one of the most economically important plant viruses and has a worldwide distribution and a very wide host range including plants from family Cucurbitaceae. In Serbia, on cucurbits CMV was detected in single and mixed infections with Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV). Viruses, including CMV, are constantly present in cucurbit crops, but their frequency changes by year and locality. Surveys and sample collections were conducted in cucurbit crops in the period from 2008 to 2009 at 15 localities in Vojvodina province, and sample testing was carried out using the DAS-ELISA method and commercially available antisera for six economically most important cucurbit viruses. In 2008, a total of 51 samples were collected from 13 cucurbit crops of oilseed pumpkin Olinka variety, squash, and bottle gourd and CMV was detected in a total of 55% of tested samples with symptoms of viral infection. The most common infectious type was mixed infection with ZYMV and WMV (35.3%), and then mixed infection with ZYMV (17.7%) and WMV (2%). A total of 599 symptomatic samples of oilseed pumpkin Olinka variety, zucchini squash varieties Beogradska and Tosca, squash, and winter squash were collected in 15 cucurbits crops in 2009. CMV was present in 4.4% of total collected samples, in single infections in 1.3%, and in mixed with WMV or ZYMV in 1.3%, and 1.8%. Five CMV isolates were obtained by mechanical inoculations of N. glutinosa and one of them was selected for further biological characterization. Test plants which were described to be hosts of CMV expressed symptoms characteristic for those caused by CMV after inoculations by isolate 115-08. CMV specific primers Au1u/Au2d were used to amplify an 850 bp fragment using RT-PCR method. Amplified fragment encodes the entire viral coat protein (CP) gene and partial 5' and 3' UTRs of two selected CMV isolates. Amplified fragments were sequenced and deposited in the NCBI, where they were assigned accession numbers, HM065510 (115-08) and HM065509 (151-08). The sequences of CMV isolates from Serbia shared the highest nucleotide and amino acid identity with isolates from subgroup IA, from 99.5 to 97.4% and 99.1 to 97.4%, and the lowest identities were with the subgroup II isolates from 66.9 to 64, 5%, from 75.8 to 74.1%