The impact of increased soil risk elements on carotenoid contents

A pot experiment was conducted to compare the responses of a non-transgenic tobacco plant (WT) and plants with genetically prolonged life-span (SAG) to risk elements of As, Cd and Zn. Plants were grown in control soil and in soil with higher levels of risk elements. The pigment contents were established by HPLC and chlorophyll fluorescence parameters were measured from slow kinetics after a 15 min dark period with the PAM fluorometer. Top (i.e. young) leaves of both WT and SAG plants were more sensitive to photoinhibition caused by these risk elements but plants showed acclimation to such elements in the bottom leaves. Plants differed in the participation of individual pigments of xanthophyll cycle: increased levels of risk elements seem to stimulate especially first (violaxanthin to antheraxanthin) and second (anhtheraxanthin to zeaxanthin) steps of the cycle in WT plants. In SAG plants, toxic elements caused an increase in the content, particularly of the initial compound of the cycle — violaxanthin.