Subgenomic mRNA transcription in Tombusviridae

Members of the large virus family Tombusviridae are plus-strand RNA viruses that infect a wide variety of plant hosts. As part of their gene expression strategy, these viruses transcribe viral subgenomic (sg) mRNAs during infections. These short viral messages are synthesized so as to allow for efficient translation of a subset of viral genes. Over the past decade, evidence has been mounting that different members of this virus family utilize a premature termination mechanism for transcription of their sg mRNAs. Here, we describe what is currently known about this unique transcriptional process as gleaned from studies on members of Tombusviridae.