Abstract
Cross-talk between exogenous salicylic acid (SA) and endogenous phytohormone pathways affects the antioxidant defense system and its response to salt stress. The study presented here investigated the effects of SA treatment before and during salt stress on the levels of endogenous plant growth regulators in three barley cultivars with different salinity tolerances: Hordeum vulgare L. cvs. Akhisar (sensitive), Erginel (moderate), and Kalaycı (tolerant). The cultivars’ relative leaf water contents, growth parameters, proline contents, chlorophyll a/b ratios, and lipid peroxidation levels were measured, along with the activities of enzymes involved in detoxifying reactive oxygen species (ROS) including superoxide-dismutase, peroxidase, catalase, ascorbate-peroxidase, and glutathione-reductase. In addition, levels of several endogenous phytohormones (indole-3-acetic-acid, cytokinins, abscisic acid, jasmonic acid, and ethylene) were measured. Barley is known to be more salt tolerant than related plant species. Accordingly, none of the studied cultivars exhibited changes in membrane lipid peroxidation under salt stress. However, they responded differently to salt-stress with respect to their accumulation of phytohormones and antioxidant enzyme activity. The strongest and weakest increases in ABA and proline accumulation were observed in Kalaycı and Akhisar, respectively, suggesting that salt-stress was more effectively managed in Kalaycı. The effects of exogenous SA treatment depended on both the timing of the treatment and the cultivar to which it was applied. In general, however, where SA helped mitigate salt stress, it appeared to do so by increasing ROS scavenging capacity and antioxidant enzyme activity. SA treatment also induced changes in phytohormone levels, presumably as a consequence of SA-phytohormone salt-stress cross-talk.
Highlights
Cereals are the main source of nutrients for all societies around the world
In this study we investigated the effects of salicylic acid (SA) treatment before and during salt stress on the different growth and physiological parameters in three barley cultivars with different salinity tolerances: Akhisar, Erginel, and Kalaycı
The barley seedlings were randomly divided into nine groups: C; 150; 300; pSAC; pSA150; pSA300; co-treatment under non-saline conditions (cSAC); cSA150 and cSA300
Summary
Cereals are the main source of nutrients for all societies around the world. these plants are often grown under adverse environmental conditions. Phytohormones, which occur in very low concentrations in plants, are key regulators of plant growth and development under stress conditions. To improve salt tolerance and mitigate the adverse effects of salt stress, several researchers have investigated the physiological, biochemical, and molecular responses of various plant species to treatment with exogenous phytohormones including indole-3-acetic acid (IAA), CK, GAs, ABA, JA, BR, and ethylene[12,13,14,15,16]. More recent studies have examined the effects of treatment with exogenous SA on physiological and biochemical processes including antioxidant mechanisms, seed germination, and plant growth under the influence of salt s tress[3,19,20]. Two studies have examined the mode of action of SA under saline conditions; one focusing on the accumulation of ABA, IAA, and selected CKs in wheat s eedlings[25], and one focusing on the accumulation of ABA and IAA in corn[26]
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