Beet black scorch virus (BBSV) is a soil-borne Necrovirus found on sugar beet in China, Spain, USA, California and more recently in Iran. The virus is sometimes associated with a satellite RNA, found in China and Iran. Over 200 samples gathered in Iranian sugar beet fields have been analyzed for the presence of BBSV and its satellite, hence revealing a wide diversity. 61 different Iranian BBSB sources have been recorded, a large number of which were associated with the satellite. The whole genome of BBSV isolates and satellites from several Iranian sugar beet growing areas have been sequenced. Full length clones of BBSV were generated by simply amplifying the viral genome before cloning into the pDrive vector (Qiagen) before generating infectious RNA transcripts. Comparison of the virus sequences stress the numerous changes in the 3’ untranslated terminal region at the nucleotide level, yet with limited impact on the structure. A sequence homologous to Argonaute was found lying within the satellite RNA. This finding raises the possibility that the satellite is acting as a suppressor of gene silencing , by targeting RNAi itself. As for other Tombusviridae, such finding stimulates interest in a better understanding of the intriguing interaction between the virus and its satellite RNA.

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