Biochemical analysis of transgenic tobacco lines producing bacterial serine acetyltransferase

The preliminary biochemical analysis of the selected lines of transgenic tobacco producing Escherichia coli serine acetyltransferase (SAT, EC 2.3.1.30) targeted either to the chloroplasts or to the cytosol was performed. The selected enzymatic activities and chemical composition of the leaf tissues collected from the plants cultivated in vivo were examined and statistically evaluated. In all SAT-over-producers increased level of non-protein thiols in comparison with the controls was detected and a higher resistance of the leaf tissue to the oxidative stress generated by hydrogen peroxide was observed. These two factors were significantly positively correlated only in plants producing bacterial SAT in the cytosol. Moreover, in the 'cytosolic' but not 'chloroplastic' groups, a strong negative correlation between glutathione and sulfate levels was seen. The leaves of most SAT-over-producers contained more protein. sulfur, calcium and iron (but less phosphorus, potassium and sodium) than the leaves of control plants, The vast majority of transgenics had higher glutathione S-transferase activity. All plants producing foreign SAT in the cytosol had an elevated activity of O-acetyl-serine (thiol) lyase, while in most plants from 'chloroplastic' groups, this activity remained closed to the control level. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.