Properties of a novel satellite RNA associated with tomato bushy stunt virus infections

Abstract

The biological and molecular properties of a novel satellite RNA (satRNA L) associated with tomato bushy stunt virus (TBSV) are described. satRNA L consisted of a linear single-stranded RNA of 615 nt, lacked significant open reading frames (ORFs) and had no sequence identity with the helper genome other than in the 59-proximal 7 nt and in a central region that is also conserved in all tombusvirus genomic, defective interfering and satellite RNAs. Secondary-structure analysis showed the presence of high-order domains similar to those described for other tombusvirus RNAs. Shorter-than-unit-length molecules were shown not to be related to a silencing mechanism. satRNA L did not modify the symptoms induced by TBSV under any of the temperature conditions tested. A full-length cDNA clone was constructed and used in co-inoculations with transcripts of carnation Italian ringspot virus (CIRV) and cymbidium ringspot virus (CymRSV). CIRV, but not CymRSV, supported the replication of satRNA L. Using CIRVCymRSV hybrid infectious clones, two regions were identified as possible determinants of the different ability to support satRNA L replication. The first region was in the 59-untranslated region, which folds differently in CymRSV in comparison with CIRV and TBSV; the second region was in the ORF1-encoded protein where a more efficient satRNA L-binding domain is suggested to be present in CIRV.

Agents Resembling or Altering Virus Diseases

“…It is thought that this structure is involved in enhancing satRNA accumulation and inducing programmed cell death (PCD) in tomato ( Figure 5.13) Xu and Roossinck, 2000). of satRNAs [B1 (822 nt), B10 (612 nt), and L (615 nt)] (Rubino and Russo, 2010) and one type of CymRSV (621 nt). The D4-satRNA induces PCD in developing phloem cells either by some metabolic perturbation or by a direct unidentified effect.…”

“…The complex pathway leading to CMV/satRNA systemic necrosis. The presence of the TBSV B10 satRNA attenuates disease symptoms, but the other three tombusvirus satRNAs influence disease expression directly; CymRSV may alter symptomatology by affecting defective interfering (DI) RNA accumulation (see Chapter 7, Section IV, C) (Rubino and Russo, 2010). Secondary cell death then occurs via a signal such as hydrogen peroxide or ethylene in nearby infected cells.…”

“…The four tombusvirus satRNAs have various features in common but also some differences (see Rubino and Russo, 2010):…”

“…However, CymRSV-sat and TBSV sat L have an A at this position, and it is thought that they may replicate by a different strategy to that of the viral genomic and DI RNAs (Rubino and Russo, 2010). However, CymRSV-sat and TBSV sat L have an A at this position, and it is thought that they may replicate by a different strategy to that of the viral genomic and DI RNAs (Rubino and Russo, 2010).…”

Biologically-supported structural model for a viral satellite RNA

“…Tombusviruses are among the best experimentally-explored plus-strand RNA plant viruses, both at the protein and RNA level ( 35 – 40 ). Two members of this genus, Cymbidium ringspot virus (CymRSV) and Tomato bushy stunt virus (TBSV), have cognate satRNAs ( 41 – 43 ). The satRNA associated with CymRSV (sat-Cym) has been most extensively characterized, and several noteworthy features have been uncovered ( 44 – 48 ).…”