Mechanism of Oxidative Stress Tolerance in Plants

Generally the use of light energy by most photosynthesizing organisms is saturated at 25-50% of sunlight. In other words, they are commonly exposed to more light energy than they required for normal photosynthesis. When leaves are irradiated by excess light energy, the chloroplasts that carry out photosynthesis can easily suffer oxidative stress and stop the process of photosynthesis. When excess light energy is absorbed by plants during photosynthesis, some harmful reactive oxygen species are produced and these reactive oxygen species break down important structures such as proteins and membranes, preventing them from functioning properly. A team of researchers with associate Professor Miyake Chikahiro (Kobe University Graduate School of Agricultural Science) have discovered the system used by plants to prevent oxidative stress and to safely carry out photosynthesis.

They discovered that plants used P700 oxidation system, to suppress the production of reactive oxygen species.P700 is the particle of chlorophyll in the reaction center of photosystem I, that transforms oxygen into reactive oxygen species.This system, common to photosynthetic organisms, starts to function when excess light energy is present (caused by environmental stresses such as strong sunlight, drought, or lack of nutrients). This P700 oxidation is essential for the growth of cyanobacteria, and it also functions in algae, moss, ferns, gymnosperms and angiosperms.

By:-Dr. Sandeep Dhyani
HOD, Department of Botany
Uttaranchal (P.G.) College Of Bio-Medical Sciences & Hospital