The present study was carried out in two seasons from two areas at different distances from the industrial zone of Gabes city which is classified as a Mediterranean host-spot pollution region. Pomegranate tree were highly exposed to various industrial air pollutants containing Zn and Cu. The relation between Zn, Cu, morphological, physiological and biochemical changes induced in pomegranate leaves was evaluated based to the measurement of leaf heavy metals, leaf changes, total phenolic content and quali-quantification of individual phenol profile by LC-ESI-MS.Results showed that the highest levels of metals were found in the closet site to the industrial area. This accumulation varied significantly between areas and seasons and cause significant increase of necrosis leaf area, decrease of leaf area, green leaf area and specific leaf area. LC-ESI-MS analysis showed a spatial and seasonal variation of total phenolic acids and flavonoids which indicate that phenolic compounds are rigorously depending to stressful conditions. A significant positive correlation was found among total Zn, Cu, necrosis, cirsiliol, caffeic and trans-ferulic acids. This accumulation can serve as protective defensive mechanism to minimize the air pollutants effects, chelate Zn and Cu and then to improve the resistance of pomegranate trees.
Keywords: Air pollution; LC-ESI-MS; defense; heavy metals; phenolic compounds.
Few studies have focused on the impact of industrial dust particles (Cu and Zn) emitted by phosphate factory on Mediterranean trees in arid region. Furhtermore, as far as we know, none of them have considered the variation and the relation between the individual phenolic acids, flavonoids, growth parameters and heavy metals considering the role of meteorological conditions. Therefore, this is one of the first studies which interested in the impact of seasonal Cu and Zn on the physiological and the biochemical parameters of pomegranate trees growing in a Mediterranean hot-spot pollution region. Moreover, the spatial and seasonal variation of phenolic acids and flavonoids was evaluated by LC-ESI-MS. PCA and correlation analysis were also determined to establish the relation between all the studied parameters.