Chemistry Reference
In-Depth Information
Chapter 10
Salicylic Acid-Mediated Abiotic Stress
Tolerance
M. Pál, G. Szalai, V. Kovács, O. K. Gondor and T. Janda
Abstract Plants are exposed to many environmental stresses, which are further
aggravated by the effects of global climate change. So investigations on com-
pounds capable of reducing the stress sensitivity of plants are of great importance.
Salicylic acid is a phenolic compound produced to varying extents by a wide range
of plant species. Its usefulness in human medicine was recognized much earlier
than its role in plants. This endogenous plant growth regulator participates in many
physiological and metabolic reactions. It was first demonstrated to play a role in
responses to biotic stress. Soon afterwards; however, it became increasingly clear
that salicylic acid also plays a role during the plant response to abiotic stresses
such as heavy metal toxicity, heat, chilling, drought, UV-light and osmotic stress.
Two kinds of evidence have accumulated to support this. First, endogenous sali-
cylic acid levels rise in several species when they are exposed to abiotic stress
conditions. Secondly, the application of salicylic acid at suitable concentrations
induces stress tolerance in various plant species. The use of mutants and transgenic
plants in which the synthesis, accumulation or translocation of salicylic acid is
modified could help to clarify its molecular modes of action in physiological
processes. Crosstalk with other hormones such as jasmonic acid, ethylene, abscisic
acid, gibberellic acid and cytokinin is important part of a finely tuned immune
response network. It can be seen that SA exerts an effect at several levels and its
effect also depends on several factors, such as the mode of application, the con-
centration, environmental conditions, plant species and organs, etc. In the present
chapter a summary will be given of the relationship between SA and various
abiotic stress factors in relation to biotic stress and other plant hormones, followed
by a summary of the known physiological and biochemical effects of SA that may
explain the change in stress tolerance.
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