ABSTRACT
Photoinhibition comprises of a set of complex molecular and physiological processes that lead to the inhibition of photosynthesis. In nature it is the process responsible for the reduction in photosynthesis, instigated due to unstable photosynthetic apparatus ensued by the arrival of excess excitation energy that reaches the PSII reaction center. This excess energy deactivates and damages the reaction center, especially the PSII, and thus reduces the photosynthesis. The excess of light is not the only factor accountable for the reduction in the rate of photosynthesis; many other biotic and abiotic factors which cause many types of stress in plants can be responsible for photoinhibition. Plants have well-regulated mechanisms to cope with photoinhibition operating at different levels of the photosynthetic machinery. Plants have a photosynthetic lifestyle and to manage this they have evolved very efficient cross-talk mechanisms between internal signaling networks and their growth. Plant hormones, especially signaling molecules such as jasmonates, which are synthesized only under the influence of some external or internal growth-related clue, invoke as an effector system to protect the photosynthetic machinery from photoinhibition. Jasmonates mutant studies describe the novel role of this signaling hormone in photo-protection against photo-damaged photoinhibition in plants.
