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Ferulic acid confers tolerance against excess boron by regulating ROS levels and inducing antioxidant system in wheat leaves (Triticum aestivum)

Yildiztugay, Evren, Ozfidan-Konakci, Ceyda, Karahan, Huseyin, Kucukoduk, Mustafa, Turkan, Ismail
Environmental and experimental botany 2019 v.161 pp. 193-202
Triticum aestivum, antioxidant activity, ascorbate peroxidase, boron, catalase, ferulic acid, glutathione dehydrogenase (ascorbate), glutathione-disulfide reductase, hydrogen peroxide, hydroponics, leaves, lipid peroxidation, monodehydroascorbate reductase (NADH), osmotic pressure, peroxidase, proline, seedlings, superoxide dismutase, thiobarbituric acid-reactive substances, water content, water solubility, wheat
Ferulic acid (FA; 3-methoxy-4-hydroxycinnamic acid) is a candidate for improving plant tolerance to stress conditions through improving water solubility and antioxidant activity. To our knowledge, no study has thus far explored the potential for exogenous FA application to improve tolerance against excess boron (B) in plants. For this purpose, wheat seedlings grown in hydroponic culture were treated with FA (25 and 75 μM) alone or in combination with B (4 and 8 mM). The results showed that B caused a decrease in water content (RWC), osmotic potential (ΨΠ) and proline content (Pro). FA application prevented decreases of these parameters. 8 mM B increased superoxide dismutase (SOD) activity. Superoxide anion radical (O2―) and hydrogen peroxide (H2O2) increased during B exposure, while catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR) activities did not. However, due to increased SOD activity, FA under stress successfully decreased O2― content. Additionally, exogenously applied FA under 4 mM B stress increased the activities of CAT and POX. While excess B in wheat leaves did not induce activities of APX, GR, monodehydroascorbate reductase (MDHAR) or dehydroascorbate reductase (DHAR) or increase total ascorbate (tAsA) or dehydroascorbate (DHA) contents, FA with stress did. 25 μM FA with B remarkably maintained regeneration of ascorbate and induced contents of tAsA and GSH (including the ascorbate-glutathione cycle) and induced CAT activity. Taken together, stress-induced H2O2 content significantly decreased and the scavenging of OH increased in wheat with FA application through the activation of antioxidant enzymes. Consequently, FA prevented lipid peroxidation (TBARS) caused by stress due to increased radical scavenging activity.