Ecological Indicators (Jan 2021)
Physiological responses of two different epiphytic bromeliads exposed in a polluted subtropical region in southeast Brazil characterized by seasonal climate
Abstract
Climate and atmospheric pollutants, such as ozone (O3), nitrogen oxides (NOx), sulfur dioxide (SO2), herbicides and particulate matter, can elevate the production of reactive oxygen species (ROS) and increase stress on plants. However, many plants can tolerate stress, neutralizing ROS through their antioxidant defense system and physiological mechanisms. Some, such as bromeliad species, are even able to accumulate pollutants and/or avoid the entry of pollutants into their tissues. This study aimed at investigating comparatively physiological responses of Aechmea fasciata and Tillandsia usneoides in a polluted subtropical region characterized by seasonal climate. We raised the hypothesis that the species most acclimatable physiologically to the seasonal climate will be the most appropriate for pollution biomonitoring purposes. To accomplish this, A. fasciata and T. usneoides plants were exposed in five locations in the metropolitan region of Campinas (MRC), São Paulo State, Brazil, for 22 months in 12-week cycles, totaling 8 exposure periods. Key non-enzymatic antioxidants (ascorbic acid and glutathione), chlorophylls and indicators of lipid peroxidation (hydroperoxide diene conjugated and malondialdehyde) and growth parameters were measured at the end of each exposure. Results showed that A. fasciata and T. usneoides have different strategies, especially regarding the potential to tolerate oxidative stress and grow in the subtropical region characterized by pollutants and seasonal climate. A. fasciata has a higher ability to change their antioxidant metabolism than T. usneoides to compensate the oxidative stress induced by environmental stressors in the study region, despite its higher MDA levels. The physiological parameters of A. fasciata were inversely correlated with air pollutants, revealing that the specie is responsive to fluctuations of environmental stressors. T. usneoides did not interact physiologically with air pollutants during wet periods. Therefore, we concluded that A. fasciata is a more efficient bioindicator bromeliad in a polluted subtropical region characterized by seasonal climate.
