Mateos, R.M.; Jiménez, A.; Román, P.; Romojaro, F.; Bacarizo, S.; Leterrier, M.; Gómez, M.; Sevilla, F.; del Río, L.A.; Corpas, F.J.; Palma, J.M. Antioxidant Systems from Pepper (Capsicum annuum L.): Involvement in the Response to Temperature Changes in Ripe Fruits. Int. J. Mol. Sci. 2013, 14, 9556-9580.
Abstract
Sweet pepper is susceptible to changes in the environmental conditions, especially temperatures below 15 °C. In this work, two sets of pepper fruits (Capsicum annuum L.) which underwent distinct temperature profiles in planta were investigated. Accordingly, two harvesting times corresponding to each set were established: Harvest 1, whose fruits developed and ripened at 14.9 °C as average temperature; and Harvest 2, with average temperature of 12.4 °C. The oxidative metabolism was analyzed in all fruits. Although total ascorbate content did not vary between Harvests, a shift from the reduced to the oxidized form (dehydroascorbate), accompanied by a higher ascorbate peroxidase activity, was observed in Harvest 2 with respect to Harvest 1. Moreover, a decrease of the ascorbate-generating enzymatic system, the γ-galactono-lactone dehydrogenase, was found at Harvest 2. The activity values of the NADP-dependent dehydrogenases analyzed seem to indicate that a lower NADPH synthesis may occur in fruits which underwent lower temperature conditions. In spite of the important changes observed in the oxidative metabolism in fruits subjected to lower temperature, no oxidative stress appears to occur, as indicated by the lipid peroxidation and protein oxidation profiles. Thus, the antioxidative systems of pepper fruits seem to be involved in the response against temperature changes.
Conclusions
Our results show that antioxidants from pepper fruits are involved in the response to temperature changes underwent due to local climatology. Pepper is a plant from tropical origin drastically affected by temperatures below 15 °C. However, in the conditions used in this work, with a set of fruits developing and ripening in planta at an average temperature of 12.4 °C, the antioxidative systems seem to compensate and buffer the imbalances generated under those unfavorable conditions. Thus, although great changes occur in the antioxidants from fruits subjected to temperature below 15 °C, no oxidative stress takes place as indicated by the stability of the lipid peroxidation and protein oxidation, two classic parameters associated to the oxidative stress syndrome. This pattern was observed in the two cultivars used in our experiments, Vergasa which ripens towards red fruits and Biela which does as yellow, but both framed within the same pepper type, California. The response observed in our work suggests that pepper fruits from California type respond to temperature changes issuing a canonical strategy which implies the involvement of cell antioxidants.
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