Summary auto-generated
Researchers identified a spontaneous deletion in RNA 2 of Potato mop-top virus (PMTV), a soil-borne virus transmitted by the fungus Spongospora subterranea. Using RT-PCR, they discovered that a contiguous segment of 2,113 nucleotides (nucleotides 480-2592) was deleted from the internal region of RNA 2, while the 5' and 3' terminal sequences remained intact. This deletion occurred reproducibly during manual passage of two PMTV isolates and during natural fungal inoculation of plants. The deletion was also detected in purified virus particles, indicating the deleted RNA is encapsidated. Northern blot analysis showed that full-length RNA 2 remained the predominant species in infected tissues, with deleted forms present at lower concentrations. The deletion removes most of the triple-gene-block (TGB) sequence, which encodes movement proteins. The authors propose that the deletion arises through a template-switching mechanism during RNA replication, where secondary structures bring distant regions of the RNA template into proximity. Similar spontaneous deletions have been observed in other soil-borne viruses, and these deleted RNAs may function as defective interfering molecules affecting virus replication and spread.
Key findings
- A 2,113 nucleotide deletion (positions 480-2592) in PMTV RNA 2 occurs spontaneously and reproducibly during virus passage and natural fungal transmission
- The deleted RNA is encapsidated into virus particles and can be detected by RT-PCR in infected plant tissues and purified virus preparations
- The deletion removes most of the triple-gene-block sequence encoding movement proteins while creating an in-frame fusion between ORF 1 and ORF 4
- A stem-loop secondary structure formation between complementary sequences flanking the deletion likely mediates template-switching during RNA replication
- The deletion occurs in multiple PMTV isolates and may explain the erratic virus distribution and self-elimination observed in infected plants
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
A spontaneous deletion in RNA 2 of Potato mop-top virus (PMTV) was identified by RTPCR. The deletion occurred reproducibly during manual passage of two isolates of PMTV and during fungal inoculation of plants with viruliferous soil. The borders of the deletion were conserved in all instances and sequence analyses showed that a contiguous segment of 2113 nucleotides was deleted internally from the genomic RNA 2, leaving the 5'- and 3'-terminal sequences. RTPCR experiments also showed that the deletion was present in preparations of PMTV particles.