Gene expression in cadmium-tolerant Datura innoxia: detection and characterization of cDNAs induced in response to Cd2+.

The response of a metal tolerant plant to heavy metal stress involves a number of biochemical pathways. To investigate the overall molecular response of a metal-tolerant plant to heavy-metal exposure, suppressive subtractive hybridization was used to create a library enriched in cadmium-induced cDNAs from cadmium-tolerant Datura innoxia. Two differential screening steps were used to screen the cadmium-induced library resulting in 8 putative cadmium-specific cDNAs out of a pool of 94 clones. Reverse transcriptase polymerase chain reaction was used to confirm that 4 of these 8 clones were cadmium-specific, while the other 4 were induced under heat shock or in the no treatment cells in addition to cadmium exposure. All 8 cDNAs were sequenced and used to search for identification against GenBank. One of the 4 cadmium-specific cDNAs had homology to a sulfur transferase-family protein in Arabidopsis thaliana. The possible link between this result and the heavy-metal response of plants is discussed.