Phytochelatin synthase (PCS) is involved in the synthesis of phytochelatins (PCs), plays role in heavy metal detoxification. The present study describes for first time the functional expression and characterization of pcs gene of Anabaena sp. PCC 7120 in Escherichia coli in terms of offering protection against heat, salt, carbofuron (pesticide), cadmium, copper, and UV-B stress. The involvement of pcs gene in tolerance to above abiotic stresses was investigated by cloning of pcs gene in expression vector pGEX-5X-2 and its transformation in E. coli BL21 (DE3). The E. coli cells transformed with pGEX-5X-pcs showed better growth than control cells (pGEX-5X-2) under temperature (47 degrees C), NaCl (6% w/v), carbofuron (0.025 mg ml(-1)), CdCl2 (4 mM), CuCl2 (I mM), and UV-B (10 min) exposure. The enhanced expression of pcs gene revealed by RT-PCR analysis under above stresses at different time intervals further advocates its role in tolerance against above abiotic stresses. (C) 2008 Elsevier Inc. All rights reserved.