Studies on Pospiviroid isolates from solanaceous and wild plant hosts in Western Australia Alison Mackie PhD Student Supervisors: Roger Jones, Martin Barbetti, Brendan Rodoni and Simon McKirdy biosecurity built on science Cooperative Research Centre for National Plant Biosecurity
Pospiviroids 9 viroids in the Pospiviroid Genus Potato spindle tuber viroid (PSTVd) type species - First viroid to be identified - Small circular RNA molecule, only 359 nucleotides Emergency plant pest for Australia
L-R: PSTVd infected and Healthy Rutgers tomato biosecurity built on science
PSTVd hosts & transmission Primary hosts tomato and potato Natural infections reported in: - Solanaceous hosts - Avocado - Sweet potato Contact transmitted
Cape Gooseberry
Blackberry nightshade
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PSTVd detections in Carnarvon
2006 – detected in Capsicum (first report for Australia) 2008 – detected in non Solanaceous plants - Streptoglossa sp (Asteraceae), Conyza bonariensis (flaxleaf fleabane)(Asteraceae), Atriplex semilunaris (Annual saltbush)(Chenopodiaceae) and a native Malavceae species. 2009 –detected in asymptomatic tomato, capsicum and chilli crops
Flaxleaf fleabane
Annual saltbush biosecurity built on science
Pathogenicity of PSTVd 3 cultivars of tomato (Petula, Swanson and Rutgers) and 3 cultivars of potato (Nadine, Atlantic and Russet Burbank) Inoculated with the Carnarvon (“Chittering”) isolate of PSTVd Plants were assessed on symptoms expressed and yield parameters
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Pathogenicity of PSTVd – Tomato
Leaf cupping
Small apical leaves
Necrosis of leaflet midrib
Shortened internode length
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Pathogenicity of PSTVd – Tomato
L-R: PSTVd infected and Healthy Petula tomato
L-R: PSTVd infected and Healthy Swanson tomato
L-R: PSTVd infected and Healthy Rutgers tomato
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Pathogenicity of PSTVd – Tomato Petula
Total Weight
Swanson
Rutgers
Healthy
Infected
Healthy
Infected
Healthy
Infected
3274.6
784.9
3141.1
1072.4
2213.6
240.6
Infected
Healthy
Petula
Swanson
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Pathogenicity of PSTVd – Potato
Upright growth, ruffled leaf margins and reduced leaf size
Apical bunching from shortened internode length biosecurity built on science
Pathogenicity of PSTVd – Potato
L-R: PSTVd infected and Healthy Nadine potato
L-R: PSTVd infected and Healthy Russet Burbank potato
L-R: PSTVd infected and Healthy Atlantic potato biosecurity built on science
Pathogenicity of PSTVd – Potato
Russet Burbank
Total Weight
Atlantic
Nadine
Russet Burbank
Atlantic
Nadine
Healthy
Infected
Healthy
Infected
Healthy
Infected
1939.4
558.8
3383.7
368.6
3258
326.9
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Summary of Pathogenicity of
PSTVd
Weights of infected tomato and potato plants were reduced Infected plants did not produce marketable fruit or tubers Carnarvon isolate not a mild strain under glasshouse conditions
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Acknowledgements CRC NPB Horticulture Australia Ltd DAFWA
- Brenda Coutts and Stuart Vincent - Ian McPharlin and Andrew Taylor
UWA
- Rob Creasy and Bill Piasini
Rijk Zwaan Toolangi Elite Elders
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Thank you  For more information, please email alison.mackie@agric.wa.gov.au
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