Role of heme oxygenase-1 in spermidine-induced alleviation of salt toxicity during alfalfa seed germination
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This study investigated molecular mechanism of spermidine (Spd)-mediated enhancement of tolerance against salinity during alfalfa seed germination.
A combination of histochemical, physiological and molecular approaches was used to study the effect of Spd on the alleviation of salt toxicity.
Exogenously applied Spd (100 μM) and a heme oxygenase-1 (HO-1) inducer hemin (10 μM) not only up-regulated alfalfa HO-1 gene expression and increased its protein level and activity, but also significantly alleviated the inhibitory effects of 100 mM NaCl on seed germination and seedling growth. K+ to Na+ ratio was also increased. Further results revealed that total, isozymatic activities or corresponding transcripts of antioxidant enzymes, including superoxide dismutase (SOD), ascorbate peroxidase (APX) and guaiacol peroxidase (POD), were induced differentially. These antioxidant behaviors were confirmed by histochemical staining for the detection of lipid peroxidation and the loss of plasma membrane integrity. Above cytoprotective role of Spd is specific for HO-1 because the inhibitor of HO-1 significantly suppressed above responses, and some of the inhibitory effects were reversed when 10 % carbon monoxide (CO)-saturated aqueous solution was added.
Together, our results suggested that Spd-mediated alleviation of NaCl toxicity during alfalfa seed germination acts, at least partially, in a HO-1-dependent pathway.
KeywordsHeme oxygenase-1 Ion homeostasis Medicago sativa Oxidative damage Salinity Seed germination Spermidine
Medicago sativa cDNA 27
Reactive oxygen species
Zinc protoporphyrin IX
This work was financially supported by the National Natural Science Foundation of China (J1210056,J1310015), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
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