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United States Department of Agriculture

Agricultural Research Service

Research Project: Epidemiology and Management of Pierce's Disease and Other Maladies of Grape

Location: Crop Diseases, Pests and Genetics

Title: Zebra Chip disease and potato biochemistry: Tuber physiological changes in response to ‘Candidatus Liberibacter solanacearum’ infection over time

Authors
item Rashed, Arash -
item WALLIS, CHRISTOPHER
item Paetzold, Li -
item Workneh, Fekede -
item Rush, Charles -

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2012
Publication Date: April 12, 2013
Citation: Rashed, A., Wallis, C.M., Paetzold, L., Workneh, F., Rush, C.M. 2013. Zebra Chip disease and potato biochemistry: Tuber physiological changes in response to ‘Candidatus Liberibacter solanacearum’ infection over time. Phytopathology. 103:419-426.

Interpretive Summary: Zebra chip disease (ZC), putatively caused by ‘Candidatus Liberibacter solanacearum’ (Lso), is an emerging threat to potato production in North America and New Zealand. To understand the formation of ZC symptoms, levels of amino acids, phenolics, carbohydrates, and defense-associated proteins were monitored in basal (stem) and apical (budding) ends of tubers, with different potato plants left non-inoculated or inoculated once with Lso every other week from planting to harvest. Concentrations of six amino acids, ten phenolics, glucose, fructose, peroxidase, and polyphenol oxidase were greater in tubers infected with Lso for a minimum of five weeks than in non-inoculated tubers. Greater levels of nine amino acids, six phenolics, sucrose, and peroxidase were observed in basal ends of tubers compared to apical ends. Although concentrations of most amino acids, phenolics, and sugars were positively associated with ZC severity, Lso titers were not associated with levels of any analyzed compound.

Technical Abstract: Zebra chip disease (ZC), putatively caused by ‘Candidatus Liberibacter solanacearum’ (Lso), is of increasing concern to potato production in Mexico, the United States, and New Zealand. However, little is known about host tuber physiological changes that result in ZC symptom formation. This study expanded on previous ZC biochemical studies by observing levels of amino acids, phenolics, carbohydrates, and defense-associated proteins in basal and apical ends of tubers from potato plants either non-inoculated or Lso-inoculated, with different plants inoculated every other week from planting to harvest. Concentrations of six amino acids, ten phenolics, glucose, fructose, peroxidase, and polyphenol oxidase consistently increased over the course of infection in both basal (stem) and apical (budding) sides of a potato tuber. Significantly greater levels of these compounds were observed in tubers infected with Lso a minimum of five weeks compared with non-inoculated tubers. Greater levels of nine amino acids, six phenolics, sucrose, and peroxidases were observed in tuber basal ends versus apical ends. Significant associations were observed between ZC symptom severity and levels of most amino acids and phenolics. However, Lso titers were not significantly correlated with the concentrations of any analyzed compound.

Last Modified: 9/10/2014