Seasonal variations of epiphytic flora, abscisic acid production and physiological response in the brown alga Cystoseira foeniculacea (Linnaeus) Greville

Abstract

In seaweeds, growth and reproduction are affected by seasonal and environmental fluctuations during their life cycle and this requires physiological control. In order to provide insights into this questions, the influence of seasonal variations and epiphytic flora on abscisic acid production, proline biosynthesis, phenolic compounds accumulation, and activity of antioxidant enzymes in the brown alga Cystoseira foeniculacea were investigated. In summer, the highest eckol content was found in the upper and lower parts of the thallus. The highest catalase activity was measured during spring, whereas the lowest one was observed in summer. In contrast, the highest ascorbate peroxidase activity was significantly increased during spring and winter in lower parts of the thallus of C. foeniculacea. Similarly, the highest superoxide dismutase activity was measured during winter. Glutathion levels were 2- and 3-fold higher in spring compared to other seasons. The abscisic acid concentration in the lower and upper parts of the thallus showed differences between seasons. Overall, the results suggest that abscisic acid accumulation with catalase activity and proline production could be related to tolerance to increased seawater temperature during summer, while eckol accumulation might be related to epiphytic flora variations.