Fluoride affects distribution of absorbed excitation energy more in favour of photosystem 1

Abstract

The effects of fluoride on the photosynthetic electron transport chain have been studied in spinach thylakoid membranes. Inhibition in photosystem (PS) 2 electron transport rates and a subsequent increase in PS 1 electron transport rate indicated a possibility of state transitions being a mechanism of fluoride action. This hypothesis was further confirmed by the increase in fluorescence emission F735/685 at 77 K, a decrease in variable to maximum fluorescence ratio (Fv/Fm) at room temperature and increase in the absorption cross section of PS 1 suggesting that fluoride affects distribution of the excitation energy in favour of PS 1 at the expense of PS 2.

Keywords

• chlorophyll fluorescence
• spinacea oleracea
• state transitions
• thylakoid membranes