**Preface to "Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense"**

Plants are continuously exposed to a large number of abiotic stress factors during their life cycles. These influence their cellular metabolisms, physiological processes, and growth as well as development. Thus, plants have evolved inherent strategies with which to acclimatize to changing abiotic stress conditions and adapt through in-built tolerance mechanisms; however, drastic changes in climatic conditions further aggravate the impact of stress on plants, which exceeds plants' tolerance capacities. Factors such as low or high temperatures, drought or waterlogging, high salinity, ultraviolet radiation, heavy metals, nutrient stress, etc., are grouped under abiotic stress, which generates the excessive production of reactive oxygen species (ROS), causing oxidative stress. One of the essential ways through which to improve plants' tolerance and relieve the pressure of abiotic-stress-induced oxidative changes for the survival of plants is to improve the capacity of antioxidant machinery. The research/review articles included in this book provide collective knowledge on the antioxidant machinery for abiotic stress tolerance mechanisms.

> **Nafees A. Khan** *Editor*
