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CEVd-induced symptom modification as a response to a host-specific temperature-sensitive reaction
D Skoric1, M Conerly, J A Szychowski
1Department of Plant Pathology, University of California, Riverside, California 92521, USA.
Virology
|February 13, 2001
Summary
Two citrus exocortis viroid (CEVd) variants, CEVd-S and CEVd-M, showed stable, distinct symptoms in Gynura aurantiaca. CEVd-M
Area of Science:
- Plant Pathology
- Virology
- Molecular Biology
Background:
- Citrus exocortis viroid (CEVd) exists as diverse variants.
- Viroid pathogenicity is linked to specific sequence and structural domains.
- Host-pathogen interactions can be influenced by environmental factors.
Purpose of the Study:
- To investigate the natural selection and stability of two CEVd variants.
- To characterize the differential symptomology induced by CEVd-S and CEVd-M in Gynura aurantiaca.
- To explore the underlying mechanisms of variable viroid-induced disease expression.
Main Methods:
- Observation of symptom severity in Gynura aurantiaca infected with CEVd variants.
- Propagation of viroid variants through cuttings and tissue extracts.
- Inoculation with cDNA clones of viroid variants.
- Molecular modeling to predict sequence and conformational changes.
Main Results:
- Two stable CEVd variants, CEVd-S (severe) and CEVd-M (mild), were identified.
- CEVd-S induced consistent severe symptoms, while CEVd-M caused variable symptoms, from asymptomatic to severe, particularly at 40°C.
- Differential host responses could not be correlated with sequence or conformational changes in the viroid variants.
- Variable symptom expression was linked to a temperature-sensitive response in Gynura aurantiaca.
Conclusions:
- CEVd variants can arise and maintain distinct pathogenic profiles.
- Gynura aurantiaca exhibits a temperature-sensitive response influencing CEVd-M symptom severity.
- Environmental factors, specifically temperature, play a crucial role in modulating viroid disease expression in susceptible hosts.
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