Hypoxic Stress Inhibits the Appearance of Wound-Response Proteins in Potato Tubers

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Abstract
Potato (Solanum tuberosum L.) tubers respond to environmental stresses by alterations of macromolecular synthesis. In an aerobic environment tubers respond rapidly to wounding by synthesizing a set of proteins, the most prominent of which display apparent weights of 78, 48, 38, and 31 kilodaltons. These proteins become intensely labeled by [35S]methionine within 2 hours of wounding. The 78 kilodalton polypeptide has been identified by immunoprecipitation as phenylalanine ammonia-lyase. By contrast, tubers incubated in hypoxic conditions for a period as short as 1.5 hours exhibit significantly reduced incorporation of amino acids such that newly synthesized polypeptides are not detected. However, a second set of proteins is synthesized by wounded tubers after prolonged incubation in a hypoxic environment. One peptide of this set is precipitated by an antibody directed against aldolase, several of these proteins may be enzymes of glycolysis necessary for anaerobic metabolism. The results indicate that there is a complex regulatory mechanism which allows mature potato tubers to respond to changes in the environment.