Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/15/2014
Publication Date: 5/8/2014
Citation: Wallis, C.M., Rashed, A., Workneh, F., Rush, C.M. 2014. Examining the role of tuber biochemistry in the development of zebra chip in stored potato tubers. In: Workneh F, Rush CM, eds., Proc. 13th Annu. SCRI Zebra Chip Reporting Session. Fredric Printing, CO. pp. 153-157. Interpretive Summary: ‘Candidatus Liberibacter solanacearum’ (Lso) causes zebra chip disease of potato (ZC), which renders potato tubers unmarketable. Processors reject potatoes exhibiting ZC symptoms, but may accept symptomless tubers that are infected with Lso. These Lso-infected tubers may develop ZC while in storage causing problems in the manufacture of potato products. Therefore, development of ZC symptoms and ZC-associated changes in physiology were observed in potato tubers stored at 3°C, 6°C, or 9°C for up to twelve weeks. Although storage temperature did not affect ZC symptom development after four weeks, greater phenolic and sugar levels occurred in tubers stored at 3°C than other temperatures. Greater phenolic and sugar levels in tubers were previously associated with ZC symptom progression. Results for tubers stored for eight or twelve weeks are pending. These results will define parameters to minimize ZC development in storage.
Technical Abstract: Zebra chip disease (ZC), associated with infection by the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso), is an emerging problem for potato growers in the United States, Mexico, and New Zealand. Although potato tubers exhibiting ZC symptoms will be rejected by processors, it remains possible that early, symptomless Lso-infections would progress to exhibit ZC symptoms over time in tubers held in storage. ZC symptoms were previously observed to be associated with increases in levels of certain amino acids, sugars, and phenolic compounds. Therefore, this study observes changes that occur in tuber physiology two, four, eight, and twelve weeks after Lso-positive but symptomless tubers were stored at three different storage temperatures (3°C, 6°C, or 9°C). Preliminary results that examined tubers kept for two- and four-weeks in storage observed greater levels of proline, sucrose, chlorogenic acid, and quinic acid in Lso-positive tubers kept at 3°C than tubers held at 6°C or 9°C. These results suggest that physiological shifts in response to Lso infection occurred in stored tubers.