|RASHED, ARASH - University Of Idaho|
|PAETZOLD, LI - Texas A&M University|
|WORKNEH, FEKEDE - Texas A&M University|
|RUSH, CHARLES - Texas A&M University|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2014
Publication Date: 2/1/2015
Citation: Wallis, C.M., Rashed, A., Chen, J., Paetzold, L., Workneh, F., Rush, C.M. 2015. Effects of potato-psyllid-vectored ‘Candidatus Liberibacter solanacearum’ infection on potato leaf and stem physiology. Phytopathology. 105:189-198.
Interpretive Summary: Zebra chip disease, caused by the bacterial pathogen ‘Candidatus Liberibacter solanacearum’ (Lso), is a substantial threat to potato production throughout the western United States, Mexico, and New Zealand. Recent studies have made great progress in understanding host reactions to Lso infection within tubers. However, understanding how other potato tissues react to Lso infection is poorly understood. Foliar and stem levels of amino acids, sugars, phenolicS, and terpenoids were compared between non-infected and Lso-infected potato plants. Lso-infected plants were observed to have shifts in foliar and stem metabolism characteristic of plant host defense responses, including increased levels of phenolics and terpenoids. This study improves understanding not only about how potato plants respond biochemically to Lso, but also how plants in general respond to bacterial pathogens.
Technical Abstract: The bacterium ‘Candidatus Liberibacter solanacearum’ (Lso) is associated with zebra chip disease (ZC), a threat to potato production in North America and New Zealand. Previous studies observed that Lso infection causes potato tubers to undergo ZC-symptom associated shifts in physiology, such as increased levels of amino acids, sugars, and phenolics. However, little is known about how Lso infection affects metabolism in other potato tissues. Therefore, this study compared foliar and stem levels of amino acids, sugars, phenolics, and terpenoids in non-infected and Lso-infected potato plants. Levels of asparagine, aspartic acid, glutamine, and sugars were lower in Lso-infected than non-infected plants. However, levels of proline, serine, particular phenolics (i.e. ellagitannins), and terpenoids were greater in Lso-infected than non-infected plants. These results were consistent with a coordinated host defense response against a pathogen, whereby precursors (such as asparagine, aspartic acid, and glutamine) were converted into defense-associated compounds (such as proline, serine, and certain phenolics).