Pollution-Induced Histochemical and Chemical Adaptation in Pinus Needles from the Palermo Area (Italy)

We examined adaptations in histochemical composition and chemical element content in pine needles caused by pollution stress. Phenol content and trace element concentrations were measured in mature needles of Pinus halepensis Mill. and Pinus pinea L. from an urban ecosystem (the city of Palermo, Italy) and compared with samples collected in periurban sites where air pollution is presumably lower. Macro-, microand toxic element concentrations in needles are affected by urban pollution, seasonal conditions and by the passage of time: pollutant capture rates and phenol accumulation remain high in bioindicator plants; this indicates a sub-pathological reactivity to persistent stress factors that activates the plants’ detoxification mechanism, prompting secondary metabolite production. Phenol content is positively correlated with some toxic elements (trace metals). Although this manuscript summarizes the results of a study conducted during a specific period, our findings can be considered representative and generalizable. The plants chosen for our investigations, P. halepensis and P. pinea, are widely used as ornamental plants in many cities, including Palermo, where it is also employed as a biomonitor to check the quality of the environment. _____________________________________________________________________________________________________________