Response of Spirodela polyrhiza to cerium: subcellular distribution, growth and biochemical changes

摘要: Rare earth elements are new and emerging contaminants in freshwater systems. Greater duckweed (Spirodela polyrhiza L.) is a common aquatic plant widely used phytotoxicity tests for xenobiotic substances. In this study, the cerium (Ce) accumulation potential, distribution of Ce bio-molecules, ensuing biochemical responses were investigated greater fronds when they exposed to (0, 10, 20, 40, 60μM). There was concentration dependent increase accumulation, which reached maximum 67mgg-1 dry weight (DW) at 60μM after 14 d. The concentrations bio-macromolecules followed order: cellulose pectin > proteins polysaccharides lipids. response exposure, significant chlorosis; declines growth, photosynthetic pigment protein contents; cell death noted highest concentration. Photosystem II inhibition, degradation reaction center D1, damage chloroplast ultrastructure observed treated S. fronds, as revealed by chlorophyll fluorescence transients, immunoblotting, transmission electron microscopy (TEM). O2.- malondialdehyde (MDA) content increased manner, indicated that oxidative stress unsaturated fatty acids (C18:3) specifically affected exposure. These results suggest exerts its toxic effects on photosynthesis, with primary effect PS II, through stress.