Evaluation of the changes in biochemical and physiologica parameters as indicators of heavy metal pollution

EVALUATION OF THE CHANGES IN BIOCHEMICAL AND PHYSIOLOGICAL PARAMETERS AS INDICATORS OF HEAVY METAL POLLUTION A. Rivetta, N. Negrini, M. Cocucci Department of Plant Physiology and soili chemistry, University of Milan, Milan Italy The lIse of biological system, particularly plants, could be an useful tool in monitoring polluted environments. It is known that plants incubated in the prc ,,:,cllce of heavy metals can accumulate thiels, low molecular weight molecules rich in cysteine and can change the level and the express ion of many enzymatic activit ies. [n this work wc consider the possibility to use the changes in the !evel of acid-soluble thio ts, as physiological markers of heavy metal pollution. [nroots and shoots of two different spec ies, the level of acid-solu ble th iols earl y and strongly increased when incubated in the presence of Cd2+. Thiols level also increased in plants grown on a soil-like standard substrate supplied with different amounts of Cd2+ or with increasing amounts of a heavy metal po[(utcd soil up to 10% (dry wt:dry \Vt). In both cases, when Cd2 in plant shoots reached the same level (30 nmol g [ fw), the increase in thiols level was higher in plants grown in the presence of polluted soil than Cd2+. Anyway, the increase in the level of thiols was not accompanied by the inhibition of plant growth, as indicated by the 51igh changes in fresh weight. protein and chlorophy ll content, with respect to the control. These data suggest that the changes in the level of thiols may be considered a physiological parameter indicator of the presence of heavy merals in the soil and may be used also in field conditions. Moreover, using glutathione affinity chromatography, preliminary Jula suggest that changes in glutathione-dependent activ it ies , in particular glutathione transferase. may be a very sensible marker of Cd2+ stress.