We investigated whether spermidine (Spd) application alleviates salinity-induced damage in alfalfa (Medicago sativa L), and explored defence mechanisms associated with stress-related ion balance, antioxidant metabolism, and gene expression. We examined the response of 30-day-old alfalfa maintained in hydroponic culture tests for 7 days and subjected to one of six treatments: half-strength Hoagland solution (control); 1% NaCl; 10 μM Spd + 1% NaCl; 20 μM Spd + 1% NaCl; 40 μM Spd + 1% NaCl; and 60 μM Spd + 1% NaCl. In salinity-stressed plants, chlorophyll b, chlorophyll a + b, and total protein showed significant decreases, while marked increases were detected in relative electrolyte leakage, H2O2 content, glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione reductase (GR) activity, the Na+/K+ ratio, and APX1, APX2, GR, and SOD gene expression levels. Chlorophyll a and total protein content markedly increased under exogenous application of 20 μM Spd, while H2O2 content, GSH, SOD, CAT, POD, GR activity, the Na+/K+ ratio, and APX2, GR, and SOD expression levels all decreased. These results indicated that exogenous application of 20 μM spermidine effectively alleviates salinity-induced damage in alfalfa. These findings could benefit alfalfa cultivation and promote the development and utilization of saline–alkali soil.
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We are grateful to the Independent Innovation and Achievement Transformation Project of Shandong Province, the Key Research and Development Program (Industry Key Technology) of Shandong Province, and the Key Research and Development Program of Shandong Province for their support for our study.
This work was financially supported by grants from the Independent Innovation and Achievement Transformation Project of Shandong Province (2014ZZCX07402), the Key Research and Development Program (Industry Key Technology) of Shandong Province (2016CYJS05A02), and the Key Research and Development of Shandong Province (2017CXGC0306).
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Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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