Physico-chemical property of rare earths-effects on the energy regulation of photosystem II in Arabidopsis thaliana.

Photosystem II (PSII) from Arabidopsis thaliana treated by lanthanum (La(3+)), cerium (Ce(3+)), and neodymium (Nd(3+)) were isolated to investigate the effects of 4f electron characteristics and alternation valence of rare earth elements (REEs) on PSII function regulation comparatively. Results showed that REE treatment could induce the generous expression of LhcII b in A. thaliana and increase the content of light-harvesting complex II and its trimer on the thylakoid membrane significantly. Meanwhile, the light absorption in the red and blue region and fluorescence quantum yield near 683 nm were obviously increased; oxygen evolution rate was greatly improved too, suggesting that REEs could enhance the efficiency of light absorption, regulate excitation energy distribution from photosystem I (PSI) to PSII, and thus increase the activity of photochemical reaction and oxygen evolution accordingly. The efficiency order of the four treatments was Ce(3+) > Nd(3+) > La(3+) > control.