Question

What is photooxidative damage?

Answer 1

It is caused as an anomaly during the process of photosynthesis or at the time of energy formation and the while photosynthetic activity gets altered due to the formation of a reactive element causing damage.

Complete answer:
During the process of photosynthesis when the light of high intensity is produced and the concentration of carbon dioxide is low, at this condition the oxidation of oxygen is formed which is quite reactive since the energy or electrons are directly donated to the oxygen. This happens because of the direct exposure of tissues to the ultraviolet radiation due to the occurrence of the photosynthetic activity resulting in the oxidative stress.
If this stress continues then this will affect the chloroplast badly resulting in its damage thus the process of photosynthesis will no longer occur. This whole condition is called photooxidative damage or photooxidative stress. This process can be reversed when the exposure to light is according to the requirement and the concentration of the reactive elements are controlled or maintained.
The various photosynthetic pigments like carotene and xanthophylls are useful in the process of photosynthesis and help the chloroplast to undergo the process of photooxidative damage.
Oxidative stress is one of the most serious and harmful effects of stress on the plants. In this process, the reactive oxygen species are accumulated in the tissues of the plants. These reactive oxygen species are formed by the over-reduction of the electron transport chain due to the excessive excitation of energy.

Note:
The process of photooxidation that occurs inside the chlorophyll is called solarization. In this process, due to the change in the intensity of light, the starch present in the leaves disappears. At higher light intensity the process of photosynthesis is inhibited due to the pigments getting bleached and thus no photosynthetic activity.