Effect of cadmium stress on plant growth and gene expression in Brassica napus seedlings.

In order to reveal the effects of Cd stress on the growth of B. napus seedlings, phenotype, physiological responses, and gene expression of B. napus under different concentration of Cd treatment were investigated through pot experiment. Our results showed that B. napus seedlings had a certain degree of tolerance to low concentration of Cd treatment since no significant difference in phenotype was observed between plants under 5 mg/kg and control. However, higher concentration of Cd treatment (30 and 50 mg/kg) could suppress the growth of B. napus seedlings, as the plant height, fresh weight, leaf area and chlorophyll content of B. nupus under higher concentration of Cd decreased significantly as compared with control, while soluble protein content and activities of two antioxidant enzymes (SOD and POD) increased significantly. The Cd content in both roots and leaves of oilseed rape increased sharply with the increased of Cd concentration. Meanwhile, Cd treatment also affected the accumulation of other metals in plants, such as Mn, Mg, Zn and Cu. Comparative transcriptome analysis of B. napus under different concentration of Cd treatments found that these differentially expressed genes were mainly concentrated in the anti-oxidant activity, photosystem, ATPase activity, cell wall organization or biogenesis and so on. Analysis of the expression patterns of HMA gene family showed that HMA3 was up-regulated, HMA2 and HMA4 were down regulated in roots of B. napus under Cd treatments when compared with control. These differentially expressed genes might have contributed to Cd tolerance of B. napus. [ABSTRACT FROM AUTHOR]