Impact of Zebra Chip Disease on the Mineral Content of Potato Tubers

Zebra chip (ZC) is an emerging and damaging disease of potato (Solanum tuberosum L.) that has been documented in potato fields throughout the southwestern United States, Mexico, Central America, and most recently New Zealand. The bacterium "Candidatus Liberibacter" has been putatively identified as the causal agent of this disease and the potato psyllid, Bactericera cockerelli (Sulc), as the insect vector. Tuber symptoms of ZC-infected plants include collapsed stolons, enlarged lenticels, vascular tissue browning, medullary ray discoloration, and necrotic flecking. ZC tuber symptoms are similar to those of potato diseases which exhibit perturbations in tuber mineral composition resulting in internal necrotic disorders. To determine the effect of ZC disease on the mineral content of potato tubers, concentrations of P, K, S, Ca, Mg, Na, Fe, Al, Mn, Cu, Zn, and B were analyzed in 'Atlantic' potatoes from ZC-infected and free plants, for both tuber flesh and peel tissues. The potatoes were grown at Weslaco, TX and Wapato, WA, two different and distant geographical locations under controlled cage conditions. Results showed that flesh tissue from ZC-infected tubers had significantly higher concentrations of P, K, and Ca at both locations, whereas, ZC-infected tuber flesh from Weslaco had higher concentrations of Mg, Cu, Zn, and B, while concentrations of Fe and Al were higher in ZC-infected tuber flesh from Wapato. Peel tissue from ZC-infected tubers were found to have a significantly higher level of Zn at both locations, whereas the levels of P and Na were found to significantly higher in peel tissue from Wapato and Weslaco, respectively. Finally, Mg was found to be significantly higher in ZC-free tubers from both locations and levels of Cu and B were significantly higher in ZC-free peel tissue from Wapato.