Stress mechanisms and adaptations in plants

In natural conditions, plants are exposed to abiotic and biotic stresses. Abiotic stresses includes water stress, temperature stress, salinity stress, heavy metal stress and photo-oxidative stress while biotic stresses caused by biological factors like pests, pathogens or herbivore attack. These stresses affect the plant growth and development at the morphological, physiological, biochemical and molecular levels which either directly or indirectly affect the crop productivity. Plants possess various tolerance mechanisms that alter various gene expressions to bring about specific response to the stress. Additionally, researchers also used mitigation strategies like exogenous application phytohormones and alteration of plant genome by introducing stress tolerant genes which help the plants to cope with the stresses. In this review, we aim to discuss the various abiotic and biotic stresses, plant tolerance mechanism, mitigation of stress through phytohormones, various molecular approaches and cross tolerance between abiotic and biotic stresses.