U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


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Published in Physiological and Molecular Plant Pathology (2001) 59, 25-32.


Plant suspension cells have been shown to respond to bacteria or microbial elicitors by producing active oxygen as well as increasing oxygen uptake. Here we characterize a unique two stage oxygen uptake response of potato suspension cells to heat-killed bacteria. Stage 1 occurred within minutes after the addition of heat-killed bacteria; the potato suspension cells responded with a rapid increase in oxygen uptake and reached a steady state approximately 50 % greater than the initial basal rate. Stage 2 began 20-30 min after this new steady state was achieved and was characterized by a slow increase in the oxygen uptake rate over the remaining 90 min period. Calculation of the total oxygen consumption by the plant cells indicated that only a small fi-action of the increased oxygen uptake was due to the concomitant production of reactive oxygen species. The protein kinase inhibitor, K-252, inhibited the oxygen uptake response by 80-90 %, suggesting the involvement of protein phosphorylation in the oxygen uptake response. The alternate oxidase inhibitor, SHAM, inhibited the elicited oxygen uptake response by about 25 % while a combination of SHAM and KCN almost completely blocked respiration as well as the elicited response. The data indicate that mitochondrial respiration and, in particular, the alternate oxidase, play a significant role in the elicited oxygen uptake response of potato cells.