ISHS Acta Horticulturae 464: International Postharvest Science Conference Postharvest 96
ROLE OF PYRUVATE IN REGULATING REACTIVE OXYGEN LEVELS IN PLANT TISSUES |
| Author: | A.C. Purvis |
| Abstract:
Reactive oxygen species, produced when components of the mitochondrial electron transport chain autoxidize, are the putative causal agents in the manifestation of several stress-induced injuries, as well as being involved in senescence processes. Mitochondria isolated from green bell pepper (Capsicum annuum L.) pericarp tissue produced less superoxide in the presence of pyruvate than in its absence. We postulated that the alternative pathway of electron transport in mitochondria, which is induced during exposure of plant tissues to chilling stress and during senescence, limits the production of superoxide (Purvis and Shewfelt, 1993). The alternative oxidase is activated by pyruvate and other  -keto acids, when the intermolecular disulfide bonds of the enzyme are reduced.
Under such conditions, little superoxide is produced.
Inhibition of the alternative oxidase with disulfiram enhanced superoxide production in the presence of pyruvate.
Pyruvate may also act as an antioxidant, reducing reactive oxygen species directly (Varma et al., 1995). The antioxidant activity on superoxide, however, appeared to be minimal.
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