Phosphate deficiency suppresses expression of light-regulated psbO and psbP genes encoding extrinsic proteins of oxygen-evolving complex of PSII.

摘要

Phosphate (Pi) is one of the important mineral nutrients influencing growth and development of plants. Prolonged Pi starvation is known to influence the light-saturated rate of photosynthetic evolution of O2. The genes psbO and psbP encode 33 and 23 kDa extrinsic proteins respectively, that play a critical role in the structural and functional integrity of oxygen-evolving complex (OEC) of the photosystem II (PSII). Although the role of Pi in photosynthesis is well documented, the effect of its deficiency on the expression of these genes has not been elucidated. In this study, we analysed the expression of psbO and psbP genes in Arabidopsis thaliana supplemented with different concentrations of Pi. A concurrent increase in the transcript levels of these genes was observed with an increase in the concentration of Pi in the medium, suggesting a role for Pi in the regulation of these genes. These results were further substantiated by time-course studies where a complete suppression of psbO and psbP genes was observed in plants starved of Pi for 7 days. The suppressive effect of Pi deficiency on these genes could be alleviated by replenishment with Pi. Fe deficiency had only a moderate effect on the expression of these genes. The effects of Pi stress on the expression of these genes could have potential implications on the structural integrity of OEC and consequently its O2 evolving efficacy..