Salicylic Acid-Mediated Abiotic Stress Tolerance - Salicylic Acid: Plant Growth and Development - page 226

receptor-like kinase, (b) PR-proteins, heat shock proteins and proteins with a direct
anti-pathogenic effect, such as chitinases and b-1,3-glucanase, (c) antioxidant
enzymes,enzymes neutralizing toxic compounds and ozmoprotectants, (d) the
enzymes of respiration and photosynthesis, such as AOX, isocitrate lyase and
ATP-synthase, (e) proteolysis-regulating proteins, such as proteasome, (f) cyto-
skeleton proteins, like tubulin and plant cell wall proteins, such as PRP, and (g)
complexing proteins, such as glycine-enriched RNA-binding protein (Tarchevsky
et al. 2010 ).
6 Conclusions
Based on the above, SA could be useful as a protective compound improving the
abiotic stress tolerance of plants. Exogenous SA treatment at a suitable concen-
tration is able to protect plants against stress-induced injury; however, the treat-
ment itself may also cause stress to the plants. Furthermore, SA treatment may also
alter the endogenous SA metabolism, either by inducing de novo synthesis or by
disturbing it. The effect of SA depends on several factors, such as the mode of
application, the concentration, environmental conditions, species and organ, etc.
Although a number of questions remain unanswered, it can be seen that SA exerts
an effect at several levels. Both endogenous and exogenous SA have a local, direct
effect at molecular level, for example in the control of ROS production. SA is also
involved in general stress responses, in a complex relationship with other plant
hormones, leading to the regulation of gene expression.
Acknowledgments The authors wish to thank Barbara Harasztos for revising the English.
Magda Pál is a grantee of the János Bolyai Scholarship. This work was supported by the Hun-
garian National Scientific Research Foundation (OTKA PD83840, K101367 and K104963).
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