Bioaccumulation and changes in the photosynthetic apparatus of Prosopis juliflora exposed to copper
The effect of copper toxicity on the photosynthetic activities and bioaccumulation in different tissues of <em>Prosopis juliflora</em> was investigated using three CuSO<sub>4</sub> concentrations (10, 50 and 100 mM) added under hydroponic conditions. Copper concentration and chlorophyll fluorescence were measured after 48 h of copper stress. The results obtained in this study show that increasing levels of 50 and 100 mM Cu<sup>2+ </sup>resulted in a significant accumulation of this metal mainly in roots compared with control roots. On the other hand, our result showed a significant reduction of maximum photochemical efficiency of photosystem II (F<em>v</em>/F<em>m</em>) and the activity of photosystem II (F<sub>v</sub>/F<sub>0</sub>) ratios in <em>P.</em><em> </em>juliflora leaf treated with<em> </em>100 mM Cu<sup>2+</sup> with respect to control after 4h of exposure. These changes suggested that the photosynthetic apparatus of P. juliflora was the primary target of the Cu<sup>2+ </sup>action. Therefore the information provided by this short-term (48 h) experiment in <em>P. juliflora</em> showed that several physiological processes are activated, in which the copper uptake by roots and their accumulation in tissues play a central role. In conclusion, the chlorophyll fluorescence parameters can be used as a useful physiological tool to assess early changes in photosynthetic performance of <em>P.</em> juliflora in response to copper pollution in short-term. Finally, the present study showed that <em>P. juliflora </em>is a promising prospect for heavy metals phytoremediation purposes occurring in arid and semi-arid climates in the northwest Mexico.