Cadmium induced physio-biochemical and molecular response in Brassica juncea.

Cadmium is a hazardous heavy metal; its presence in the agricultural soil constrains the crop productivity and restricts crop plants from reaching their full genetic potential. In the present study, two Brassica juncea cultivars (Pusa Bold and Pusa Jaikisan), were exposed to different concentrations of cadmium (Cd) as cadmium chloride (CdCl2) (50 microM, 100 microM, 150 microM, and 200 microM). The effect of cadmium on seed germination ratio, changes in the root and shoot length, plant dry weight, moisture content, metal tolerance index, antioxidant enzyme activity and lipid peroxidation were studied. The consequence of cadmium stress at the molecular level was studied using a key gene Phytochelatin Synthase (PCS). The results of our study suggested that, exposure of cadmium affected the seed germination, growth rate, biomass content and antioxidant enzyme activities in the root, shoot and leaves of both the cultivars. Transcript expression of PCS was increased with increasing CdCl2 concentration in both the cultivars. Based on the results, it was concluded that, Brassica juncea Cv Pusa Jaikisan is more tolerant to cadmium toxicity than the Pusa Bold. These findings could be used to develop heavy metal stress tolerant plants and more importantly, detoxification of heavy metals in the soil.