Effect of cadmium on photosynthesis and enzymes of photosynthetic sulphate and nitrate assimilation pathways in maize (Zea mays).
1994
Ferretti M. | Ghisi R. | Merlo L. | Dalla Vecchia F. | Passera C.
Chlorophyll content, photosynthetic oxygen evolution and the activities of ATP-sulphurylase (ATP-s), OAS-sulphydrylase (OAS-s), nitrate reductase (NR) and glutamine synthetase (GS) were determined in leaves of Zea mays cv. Sponsor plants grown in the presence of 0, 10, 100, 250 microM Cd in order to evaluate the effect of this metal on sulphate and nitrate assimilation pathway. Cd induced a slight decrease of photosynthetic oxygen evolution (-21 % of the control at 250 microM), whereas the enzyme activities were differently induced: OAS-s and GS increased up to 40 and 25 % of the control, respectively, at 250 microM Cd; NR showed a 20 % stimulation at 100 microM Cd, and ATP-s was slightly inhibited. The results stress the importance of experimental conditions adopted on the response of enzyme activities to Cd and suggest that the observed increases of enzyme activities are related to a defence mechanism.
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