Role of antioxidant phenolic compounds in plant responses to environmental stress

Autores UPV


Adverse environmental conditions cause oxidative stress in plants by generation of ¿reactive oxygen species¿ (ROS), to which plants respond activating enzymatic and non-enzymatic antioxidant systems. Many phenolic compounds, especially flavonoids, are known antioxidants and efficient ROS scavengers in vitro; this activity appears to be the reason for their attributed beneficial effects for human health. There are evidences for the involvement of phenolics/ flavonoids in plant responses to abiotic stress, mostly based on experiments with model species under controlled (but artificial) greenhouse conditions; yet their role in stress tolerance mechanisms in nature is still unclear. There are large quantitative and qualitative differences in antioxidant phenolics in plant taxa, which makes it difficult to generalise the results obtained for particular species. Moreover, phenolics fulfil many different biological functions in plants, which can mask their specific effects on the defense against environmental stress. Our strategy to assess the biological relevance of these secondary metabolites in abiotic stress tolerance mechanisms is based on the correlation between the levels of total phenolics and antioxidant flavonoids and the degree and type of stress, in plant material collected in the field from a relatively large number of plant species growing under varied environmental conditions (different habitats, several seasons throughout the year). Despite the aforementioned difficulties, we could detect statistically significant correlations of phenolics contents with altitude and with soil and atmospheric parameters associated to water stress, thus supporting a general, ecologically relevant function of antioxidant phenolic compounds in the mechanisms of response to environmental stress in plants.