Lipid peroxidation and changes in the activity of superoxide dismutase caused by water deficit in basil (Ocium basilicum L.) and savory (Satureja hortensis L.)

Abstract

SummaryTwo aromatic species (Ocimum basilicum L. and Satureja hortensis L.) with different water requirements were submitted to varying water supply, as characterised by different soil water capacities [SWC; control (C), 70% SWC; Stress 1 (S1), 50% SWC; and Stress 2 (S2), 30% SWC] in a growth chamber. The effect of water deficit on the formation of malondialdehyde (MDA), a product of lipid peroxidation (LPO), and on superoxide dismutase (SOD) activity were evaluated at three phenological phases (before flowering, at full-flowering, and after flowering) in both plant species. The results revealed that MDA contents were significantly higher in savory than in basil. However, significant increases in MDA contents, as a consequence of changes in the water supply, were detected only in basil (by 23% and 49% in S1 and S2, respectively). In contrast, SOD activities in control plants showed similar values in both species. Elevated SOD activities were detected in basil and in savory as a reaction to water deficit stress, with maximum SOD activities occurring during full-flowering (3.212 Units mg–1 protein and 2.655 Units mg–1 protein in basil and savory, respectively). We conclude that water deficit stress (to 50% or 30% SWC) may result in increased SOD activities, which were responsible for the decreased levels of superoxide free radicals in both species examined. However, under the conditions used here, enhanced LPO was detectable only in basil, known as a plant with a high water requirement.