Mechanism of exogenous selenium alleviates cadmium induced toxicity in Bechmeria nivea (L.) Gaud (Ramie)

The protective role of exogenously supplied selenium (Se6+) on Bechmeria nivea (L.) Gaud (Ramie) subjected to cadmium (Cd) stress was studied in vitro, and the mechanism was discussed by investigating plant growth, malondialdehyde (MDA), activity of antioxidative enzymes and DNA methylation pattern. Plants grown in hydroponic culture were supplied with spraying Se (selenate, 1.2 μmol/L) and cadmium (Cd(NO3)2, 0, 3, 6 and 9 mg/L), individually or simultaneously. At low Se spraying levels, SOD activity was increased by 35.34%, 43.18%, 3.63% under 3, 6 or 9 mg/L cadmium contents, POD was increased by 12.45%, 14.14%, 3.27%, and the level of DNA methylation was decreased by 10.70%, 18.18% and 15.59%, respectively. The results confirmed that spraying low Se on ramie leaves could enhance the activity of SOD and POD, and regulate DNA methylation in ramie leaves.