Efficacy of Bioindexing for Graft-Transmissible Citrus Pathogens in Mixed Infections
G Vidalakis1, S M Garnsey1, J A Bash1
1Department of Plant Pathology, University of California, Riverside, CA 92521, U.S.A.
Plant Disease
|February 24, 2019
Summary
Bio-indexing for citrus pathogens like Citrus tristeza virus (CTV) and Citrus psorosis virus (CPsV) is effective even with multiple infections. However, some virus combinations can suppress symptom expression and diagnostic accuracy in specific citrus indicators.
Area of Science:
- Plant Pathology
- Horticultural Science
- Virology
Background:
- Graft-transmissible pathogens pose a significant threat to citrus production worldwide.
- Accurate detection of these pathogens is crucial for disease management and certification programs.
- The presence of multiple pathogens can potentially interfere with diagnostic assays.
Purpose of the Study:
- To investigate the efficacy of biological indexing for citrus pathogens in the presence of other infections.
- To evaluate the impact of multiple infections on symptom expression and diagnostic accuracy.
- To assess the utility of alternative bioassay hosts for citrus pathogen detection.
Main Methods:
- Statistical evaluation of symptom expression probability and bio-indexing test efficacy.
- Assessment of the number of citrus indicators required for pathogen detection.
- Investigation of single and multiple infections using various citrus pathogens and indicator plants.
Main Results:
- Multiple infections did not impede symptom expression or reduce diagnostic efficacy for Citrus tristeza virus (CTV), Citrus psorosis virus (CPsV), and Citrus tatter leaf virus (Apple stem grooving virus).
- Citrus vein enation virus (CVEV) symptoms and Mexican lime efficacy were suppressed by specific CTV isolates.
- Citrus psorosis virus (CPsV) suppressed symptom expression and diagnostic efficiency in Dweet tangor and sweet orange for concave gum disease.
- Alternative hosts like Dweet tangor and Citrus excelsa showed potential for CVEV detection, while sweet orange required co-infection for detection.
- Citrus excelsa effectively detected CTV, whereas Mexican lime was only efficient for specific CPsV isolates.
Conclusions:
- Bio-indexing remains a reliable method for detecting key citrus pathogens, even under multiple infection scenarios.
- Specific virus interactions can negatively impact diagnostic accuracy, highlighting the need for careful selection of indicator plants.
- Alternative bioassay hosts offer potential for improved detection of certain citrus pathogens, expanding diagnostic capabilities.
Keywords:
Clopper-Pearson confidence intervals
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