OVER-EXPRESSION OF ARABIDOPSIS PHYTOCHELATIN SYNTHASE GENE IN ORYZA SATIVACONFERS ENHANCED TOLERANCE TO HEAVY METAL CADMIUM

The heavy metal cadmium (Cd) is one of the most toxic elements. It decreases the growth rate of plants by affecting various aspects of metabolism mainly in normal uptake and utilization of macro and micronutrients. To overcome these challenges Phytochelatingenes were over expressed and developed Cd tolerance in different plants. Phytochelatins, a class of post translationally synthesized peptides, play a key role in Cd tolerance in plants by chelating the Cd substances and decreasing their free concentrations. This investigation mainly deals with cloning of Arabidopsis phytochelatingene (AtPCS1) and its effects on tolerance to Cd in transgenic rice plants. We have constructed a plant expression pCambia 1302-hyg-CaMV35S-AtPCS1-polyA-GFP binary vector, and transferred into rice calli employing Agrobacterium-mediated genetic transformation method. The transgenic plants were regenerated and grown to maturity in the glasshouse. Subsequently, PCR, Southern blot and Northern blot analyses was carried out to confirm the presence, copy number and expression of AtPCS1 gene in transgenic rice plants, respectively. Later, the homozygous lines were identified by germinating T2 resistant seeds on selection medium containing hygromycin (50 mg/L). Two homozygous transgenic rice lines (SMPC2-1-15 and SMPC5-1-10) expressing AtPCS1 of T3 generation along with un-transformed controls were used for further Cd tolerance analyses. Effect of Cd on root and shoot growths of AtPCS1 rice transformants and Untransformed Control (UC) were measured. Likewise, the accumulation of Cd in roots and shoots of AtPCS1 transgenic rice lines along with untransformed controls were also measured. The transgenic rice lines showed marked enhancement in tolerance to Cd and also disclosed increased accumulation of Cd in roots and shoots