Rieske iron-sulfur protein of cytochrome-b6f is involved in plant recovery after drought stress

Abstract

The aim of the study was to determine molecular basis of plant photosynthetic activity during soil drought and under rapid (unfavorable) and gradual (favorable) rehydration. We analyzed the content of proteins associated with the photosynthetic apparatus and photosynthetic fixation of CO2. The experiment involved two genotypes of triticale showing complete and incomplete recovery from drought stress.The reason for irreversible changes in the activity of the photosynthetic apparatus was stress-induced decrease in the content of Rieske protein (PetC) of cytochrome complex b6f. Intensification of metabolic processes during rehydration and following overload the electron transport chain led to electron transfer from primary acceptors QA/QB in PSII and ferredoxin in PSI to oxygen. The resulting reactive oxygen species oxidized proteins and inhibited synthesis of those controlling the photosynthetic apparatus and carbon fixation. The consequence was a reduction of quantum yield of electron transport to their final acceptors in PSI and lowering of plant photosynthetic activity and biomass. Simultaneous utilization of H2O2 during saturation of cell wall with phenolic compounds ensured restoration of desired level of proteins controlling the photosynthetic apparatus and photosynthetic carbon fixation, as well as high photosynthetic activity.