ABSTRACT
Aims: This whole review tells about origin of ROS, Cell death, role of ROS, defense system in numerous developmental pathways.Methodology: In plant reactive oxygen species are the main factor of cell mechanism deterioration. The stability of the reduction and regeneration is disturbed under stress environment. ROS continuously damages the main organelles of cell in plants as well as inactivate several enzymes. Break down of lipids, nucleic acid, proteins, pigments, damages in membrane which may lead to cell death.Conclusion: ROS is diffusible measures in pathways of signal transduction in numerous developmental pathways in plants. ROS acts as a messenger. Plants protect cell from misbalancing and also damages ROS production. ROS produced in excess amount rather than required for numerous metabolic reaction. In aerobic respiration ROS is produced