[Show abstract][Hide abstract] ABSTRACT: To investigate the response of cucumber seedlings to exogenous salicylic acid (SA) and gain a better understanding of SA action mechanism, we generated a proteomic profile of cucumber (Cucumis sativus L.) cotyledons treated with exogenous SA. Analysis of 1500 protein spots from each gel revealed 63 differentially expressed proteins, 59 of which were identified successfully. Of the identified proteins, 97% matched cucumber proteins using a whole cucumber protein database based on the newly completed genome established by our laboratory. The identified proteins were involved in various cellular responses and metabolic processes, including antioxidative reactions, cell defense, photosynthesis, carbohydrate metabolism, respiration and energy homeostasis, protein folding and biosynthesis. The two largest functional categories included proteins involved in antioxidative reactions (23.7%) and photosynthesis (18.6%). Furthermore, the SA-responsive protein interaction network revealed 13 key proteins, suggesting that the expression changes of these proteins could be critical for SA-induced resistance. An analysis of these changes suggested that SA-induced resistance and seedling growth might be regulated in part through pathways involving antioxidative reactions and photosynthesis.
[Show abstract][Hide abstract] ABSTRACT: Salicylic acid (SA) is one of the most important signaling molecules in plant growth and defense responses to biotic and abiotic
stresses. Here, the effect of exogenous SA on the stomatal movements was investigated in cotyledons of cucumber (Cucumis sativus L.) seedlings. Application of different SA concentrations could induce the reduction in stomatal aperture and conductance,
especially at a concentration of 0.5 mM. Using the isolated epidermal strips, stomata were found to close notably in response
to exogenous SA, even at a concentration as low as 0.001 mM. Further study showed that a SA-induced decrease in the stomatal
aperture was intensified by the higher SA concentrations, longer exposure, and lower pH of the medium. In addition, to understand
the relationship between stomatal closure and endogenous hormone contents, the levels of ABA, IAA, and gibberellin (GA3) were assayed under SA treatment. SA significantly increased endogenous ABA but not IAA and GA3 content. A significant negative correlation (p ≤ 0.01) was observed between stomatal conductance and the ratio of ABA to (GA3 + IAA) during SA application. It was suggested that exogenous SA could change the balance of endogenous hormones and thereby
induce stomatal closure in cotyledons of cucumber seedlings.
–salicylic acid–stomatal closure–endogenous hormone–abscisic acid
No preview · Article · Sep 2011 · Russian Journal of Plant Physiology