ARS | Publication request: Large-scale shifts in potato (Solanum tuberosum) tuber physiology occur following infection by ‘Candidatus Liberibacter solanacearum

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2012
Publication Date: July 1, 2012
Citation: Wallis, C.M., Rashed, A., Rush, C.M. 2012. Large-scale shifts in potato (Solanum tuberosum) tuber physiology occur following infection by ‘Candidatus Liberibacter solanacearum. Phytopathology. 102:S4.129.

Technical Abstract: Zebra chip disease (ZC), putatively caused by ‘Candidatus Liberibacter solanacearum’ (Lso), is an emerging threat to worldwide potato (Solanum tuberosum) production. The disease renders infected tubers unmarketable due to increased browning symptoms when tubers are cut or fried. Potato tubers exhibiting ZC symptoms previously were characterized as possessing increased levels of phenolics and amino acids. Both phenolics and amino acids could result in increased ZC-characteristic non-enzymatic and enzymatic browning. However, the development of phenolics and amino acids as an infection with Lso progresses has not been documented. Likewise, increased sugar levels also could contribute to browning symptoms characteristic of ZC. Thus, changes in concentrations of tuber phenolics, amino acids, and reducing sugars were monitored over nine weeks after inoculation with Lso for both apical and terminal ends of potato tubers. This study also correlated levels of phenolics, amino acids, and sugars with ZC symptoms and Lso titers. Particular phenolics, amino acids, and sugars were more concentrated in tubers infected with Lso for longer durations. Terminal ends of tubers possessed greater phenolic and amino acid levels than apical ends. Levels of phenolics, most amino acids, fructose, and glucose were significantly positively associated with tuber symptoms. However, levels of these compounds were not associated with Lso titers.