Potassium ions enhances photosynthetic tolerance to salt stress. We
hypothesized that potassium ions, by minimizing the trans-thylakoid
proton diffusion potential difference, can alleviate an over-reduced
photosynthetic electron transport chain and maintain the integrity of
the photosynthetic apparatus. This study investigated the effects of
exogenous potassium on the transcription level and activity of proteins
related to the photosynthetic electron-transport chain of tobacco
seedlings under salt stress. Salt stress retarded the growth of
seedlings, and caused potassium ion outflow from the chloroplast. It
also lowered qP (indicator of the oxidation state of Q
), Y (average photochemical
yield of PSII) while increasing Y
(non-regulatory energy dissipation), accompanied by reduced expression
of most light-harvesting, energy-conversion, and electron-transport
genes. Interestingly, Lincomycin (a D1 protein-synthesis inhibitor)
significantly diminished the alleviation effect of exogenous potassium
on salt stress. We attribute the comprehensive NaCl-induced
down-regulation of transcription and photosynthetic activities to
ROS-induced retrograde signalling. There probably exists at least two
types of ROS-induced retrograde signalling, distinguished by their
sensitivity to Lincomycin. Exogenous potassium appears to exert its
primary effect by ameliorating the trans-thylakoid proton diffusion
potential difference caused by salt stress, thereby alleviating
over-reduction of the photosynthetic electron transport chain, and
maintaining the integrity of photosynthetic proteins.
The foreword to this special issue on the advanced technologies in studying photosynthesis focuses on the main contributions of Fred Chow, one of the key Australian scientists studying light reactions in plants.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.