The Phytotoxicities Of Decabromodiphenyl Ether(BDE-209) To Different Rice Seedlings

Decabromodiphenyl ether(BDE-209)is the most commercialized PBDEs,which is extensively employed as a major component of brominated flame retardants.PBDEs tends to fall off the surface of its products and finds it way into the environment.Given that BDE-209 is toxic,ubiquitous and persistent,BDE-209 might induce toxic effects on rice cultivars planted in contaminated soil.This thesis compares the phytotoxicities of BDE-209 to different rice cultivars within the scope of 0-500 μg/L,and explores the tolerance mechanism.The main findings of this thesis are summarized below:(1)BDE-209 induced toxic effects on rice cultivars through responding mechanism.The degrees of toxic effects in the cultivars were positively correlated with their ROS contents.At the same exposure concentration,there were no significant differences in BDE-209 concentration in both sensitive and tolerant cultivars.The increases of ROS contents were the highest in sensitive cultivar compared with those in tolerant cultivars,which led to higher toxic effects in sensitive cultivars.(2)L-tryptophan and L-valine were identified as the most important antioxidant-related metabolites responsible for the separation of sensitive and tolerant cultivars.In the loading plot,these two amino acids were most positively correlated with tolerant cultivars within the nearest distance(VIP>1).At control treatment,the contents of L-tryptophan and L-valine in tolerant cultivars were 2.6 and 1.5 times as much as that of sensitive cultivar respectively;At 500 μg/L BDE-209 treatment,the contents of L-tryptophan and L-valine in tolerant cultivars were 3.1 and 1.6 times respectively.The differences in the antioxidant-related metabolites contents led to the different phytotoxicities.The up-regulation of L-tryptophan and L-valine are the tolerance mechanism of rice cultivars to BDE-209.