Effects of Pb2+ on the Structure and Function of Photosystem II of Spirodela polyrrhiza

Lead (Pb2+) is a well-known highly toxic element, and Spirodela polyrrhiza is one of the hydrophytes most sensitive to Pb2+, which might be highly toxic to photosynthesis. However, the mechanism by which Pb2+ inhibits energy transfer and conversion efficiency remains unclear. Here, we report the effects of Pb2+ on the secondary structure and function of photosystem II (PS II) of S. polyrrhiza using spectral methods. We found that Pb2+ accumulated in PS II and damaged its secondary structure, decreased the absorbance of visible light, inhibited energy transfer among amino acids within the PS II protein–pigment complex, and reduced energy transport from tyrosine residue to chlorophyll a. Taken together, Pb2+ exposure damaged the structure and function of S. polyrrhiza PS II.