THE EFFECT OF SALICYLIC ACID ON DIFFERENT PLANT PROCESSES – A REVIEW

1 Faculty of Agriculture and Natural Resources, University of Torbat Heydarieh, Torbat Heydarieh, Iran ABSTRACT. Salicylic acid (SA) is a well-known signaling molecule that plays an important role in resistance against pathogens, as well as adaptation to some abiotic stress factors, such as drought, heavy metal toxicity, chilling, heat and osmotic stress and can be a factor effective treatment for plants. The impact of SA on different plant processes under optimal environmental conditions is controversial. Also, SA as a plant growth regulator may have a positive effect on the regulation of physiological and biochemical processes of different plant species, such as seed germination, seed production, respiration, vegetative growth, flower formation and photosynthesis. In addition, SA as a regulator of cell growth, could contribute to maintaining cellular redox homeostasis by induction of the alternative respiratory pathway and the regulation of antioxidant enzymes activity and to regulating gene expression by inducing a RNA-dependent RNA polymerase. However, SA may act as a stressor, and may have a negative impact on different plant processes. Recent results indicate that the exogenous application of SA to plants have affect several on many physiological processes, such as control of ion absorption, stomatal closure and transport, reducing of stress and stimulation of growth and differentiation of plants, and also the controlled levels of SA in plants are important for improving performance and adaptation to environmental stimuli and emphasize its important role in plant health and protection. The present study investigated the effect of SA on different plant processes.