Effects of lanthanum and calcium on photoelectron transport activity and the related protein complexes in chloroplast of cucumber leaves

The effects of lanthanum and calcium ions on electron transport, dichloreph enol indophenol (DCIP) photoreduction, and oxygen evolution activities in c hloroplast from cucumber (Cucumis satives L.) were determined. The lanthanu m inhibited the whole electron chain-transport activity of chloroplast. DCI P photoreduction and oxygen evolution activities of the photosystem I (PSII ) also decrease after treatment with La3+. But the diminished activities of PSII and chloroplast caused by La3+ could be reversed by Ca2+ and even bec ame higher than the control level. The concentration analysis of related pr otein complexes to photoelectron transport in chloroplast included that La3 + induced the concentration of chlorophyll protein complexes increasing but caused some nonchlorophyll protein complexes to decompose partially. This increasing effect of La3+ on chlorophyll protein complexes results in the i mprovement of chlorophyll content, which will improve the absorption of pho toelectron and energy transport in the process of photosynthesis.