Abstract
The effects of environmental stresses on photosynthetic responses, ascorbate levels and pigment composition were investigated in samples of Parmelia quercina (Willd.) Vainio from control and polluted regions of the northern Castellón area (Valencia, Spain). In response to sustained pollutant stress in the field, lichen thalli had closed PSII traps and exhibited lower rates of electron transport and non‐radiative energy dissipation. The xanthophyll concentration was not affected by exposure to atmospheric pollutants. The ascorbate concentration was lower in samples exposed to ambient air pollutants compared to control thalli. Ascorbate feeding of thalli from polluted sites stimulated electron flow, photochemical quenching and non‐radiative energy dissipation. Additionally, ascorbate feeding enhances the de‐epoxidation state of the xanthophyll pool in polluted thalli. The partial recovery for non‐radiative energy dissipation was presumably due to the interaction between the increased thylakoid pH gradient and de‐epoxidized xanthophylls. Furthermore, ascorbate feeding decreased photon excess in thalli from polluted sites owing to the stimulation of linear electron flow and non‐radiative energy dissipation. The present study suggests that atmospheric pollutants, besides their intrinsic toxicity, put on an additional burden by hampering the operation of photoprotective mechanisms.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
