Summary auto-generated
Researchers identified and characterized beet virus Q (BVQ), a previously unknown rod-shaped virus isolated from sugarbeet in Germany. Using innovative molecular techniques, they determined the complete nucleotide sequence of BVQ's tripartite genome (three RNA segments) from unpurified virus in crude plant sap. The genome consists of RNA 1 (6003 nucleotides) encoding replication proteins, RNA 2 (2913 nucleotides) carrying the coat protein and related proteins, and RNA 3 (2529 nucleotides) containing a triple gene block involved in virus movement. BVQ shares structural and genetic features with related viruses like beet soil-borne virus (BSBV) and potato mop-top virus (PMTV). The researchers found that the 3' ends of all three RNAs can fold into tRNA-like structures similar to those in tymoviral RNAs, and the 5' ends form characteristic hairpin structures with specific mismatches. Based on genetic organization and sequence relationships, BVQ was classified as a new species in the genus Pomovirus, showing evolutionary connections to multiple rod-shaped virus groups.
Key findings
- BVQ is a new tripartite virus from sugarbeet with RNA segments encoding replication enzymes, coat protein, and movement proteins similar to pomoviruses and furoviruses
- The complete genome sequence was determined from unpurified virus using innovative RT-PCR strategies targeting conserved helicase domains, demonstrating a method applicable to other difficult-to-purify viruses
- BVQ's 3' and 5' untranslated regions contain tRNA-like structures and pseudoknots similar to tymoviral RNAs, suggesting functional importance for replication
- Amino acid sequence identities indicate BVQ is a distinct virus species rather than a strain of related viruses like BSBV
- BVQ was widely detected in sugarbeet samples across Germany and internationally, indicating significant geographic distribution
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
R Koenig, CW Pleij, C Beier and U Commandeur
Biologische Bundesanstalt fur Land- und Forstwirtschaft, Institut fur Biochemie und Pflanzenvirologie, Braunschweig, Germany. r.koenig@bba.de
Based solely on the information that beet virus Q (BVQ) contains tubular particles, the entire nucleotide sequence of its tripartite genome was determined from unpurified virus in ca. 40 ml crude sap from locally infected Chenopodium quinoa. A starting sequence for RNA 1 was generated using primers corresponding to highly conserved helicase domains in the respective RNAs of furo-, pomo-, peclu-, hordei- and tobraviruses, and was extended by a walking random-primed cDNA approach. The similarity of the 3' ends of furoviral RNAs allowed starting sequences for BVQ RNAs 2 and 3 to be obtained once the 3' end of RNA 1 was known. BVQ RNA 1 encodes a protein with a methyltransferase-like, a variable and a helicase-like region, and for a readthrough protein which, in addition, contains an RNA-dependent RNA polymerase region. RNA 2 carries the coat protein gene, a coat protein read-through protein gene and two additional ORFs which may have arisen by deletions from an originally larger readthrough domain. RNA 3 carries a triple gene block resembling that of several other rod-shaped viruses. The 5' UTRs of the three RNAs have the potential to form a series of hairpins with C-A and C-C mismatches resembling those found in tymoviral RNAs. The 3' ends can be folded into tRNA-like structures which are preceded by a long hairpin-like structure and an upstream pseudoknot domain. BVQ belongs to the recently proposed genus Pomovirus; it shows evolutionary relationships to furoviruses in sensu stricto, peclu-, hordei-, tobra-, tymo-, tobamo-, carla- and potexviruses.