Association of Satellite RNA with Grapevine fanleaf virus in its Geographical Origin and Sequence Characteristics

Abstract

The region between The Caspian Sea and Black Sea has been hypothesized as the origin of grapevine. Likewise, an extensive study on Grapevine fanleaf virus (GFLV) from this region suggests this region as a possible origin of the virus. However, as yet there is no information as to whether or not the virus variants from this region accompanied with the virus satellite RNA (satRNA) and if so, how diverse theses satRNAs can be. To answer these questions, Grapevine fanleaf virus isolates were collected from different vineyards in the northwest region of Iran for the occurrence of the satellite RNA. A total of 421 samples including Vitis vinifera, Chenopodium quinoa, C. amaranticolor, Cynodon dactylis, Medicago sativa were initially screened against GFLV by RT-PCR with the coat protein primers (Cp433, Cp912). When the GFLV-infected plants (36 samples) were screened by RT-PCR with the newly designed satRNA primers Gf750 and Gr750, three samples appeared to possess the satRNA. The satellite cDNA fragments were cloned and sequenced and when the resulting data were compared with sequences of previously-reported satRNA of GFLV and Arabis mosaic virus (ArMV), 70-98% and 69-71% similarities were found, respectively. Phylogenetic studies revealed distinctness of the satRNAs from Iran. This may suggest coevolution of the satRNA with the helper virus because GFLV isolates from this region also form a distinct branch. Among previously reported corresponding satRNA sequences to those from Slovenia and South Central Europe were the closest. This study also reports C. amaranticolor as the natural host for GFLV, which was previously reported only as an experimental host.

Keywords

• arabis mosaic virus
• double-stranded rna
• grapevine fanleaf virus
• satellite rna