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Genetic variability of potato spindle tuber viroid RNA replicon
A Góra-Sochacka1, T Candresse, W Zagórski
1Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa. annag@ibbrain.ibb.waw.pl
Acta Biochimica Polonica
|December 6, 2001
Summary
Potato spindle tuber viroid (PSTVd) genetic continuity was studied in tomato plants. New PSTVd variants emerged, causing specific symptoms, and a non-infectious mutant unexpectedly became infectious in potato, suggesting genome recovery.
Area of Science:
- Plant pathology
- Virology
- Molecular biology
Background:
- Viroids, such as potato spindle tuber viroid (PSTVd), are small, non-coding RNA pathogens that infect plants.
- Understanding viroid genetic dynamics and replication mechanisms is crucial for disease management and crop protection.
Purpose of the Study:
- To analyze the genetic continuity and evolution of the PSTVd genome in infected tomato plants.
- To investigate the role of specific genomic regions, particularly the central conserved region, in PSTVd infectivity and replication.
- To explore potential mechanisms of viroid genome recovery and adaptation.
Main Methods:
- Infection of tomato plants with cloned PSTVd cDNA of parental strains.
- Monitoring of PSTVd sequence variants and associated disease symptoms over six weeks.
- Construction and testing of a PSTVd cDNA mutant with a deletion in the central conserved region.
- Analysis of PSTVd RNA in potato transformants expressing the deleted mutant.
Main Results:
- Emergence of new PSTVd sequence variants in the progeny population, inducing sequence-specific disease symptoms.
- PSTVd populations behave as pseudo-strains, propagating as a collection of similar sequences.
- A PSTVd mutant with a central conserved region deletion was non-infectious.
- Surprisingly, an infectious viroid was detected in potato transformants expressing the deleted PSTVd RNA, indicating genome recovery.
Conclusions:
- The PSTVd genome exhibits genetic continuity through the propagation of sequence variants, consistent with pseudo-strain behavior.
- The central conserved region is essential for PSTVd infectivity, but its deletion can be overcome through specific transcript conversion and recovery of the full-length genome in certain hosts.
- This study reveals a novel mechanism of viroid genome recovery and adaptation, highlighting the complex interactions between viroids and their hosts.