Foliar applications of spermidine improve foxtail millet seedling characteristics under salt stress

Abstract

This study investigated the mitigating effects of spermidine (Spd) application on salinity-induced ion inbalance, physiological properties, and the expression of some genes in foxtail millet (Setaria italica L.). We observed 30-d-old seedlings maintained at a half-strength Hoagland solution (control), 1.0 % NaCl, 10, 20, and 40 μM Spd, and 10, 20, and 40 μM Spd + 1.0 % (m/v) NaCl for 14 d. The results show that salt stress significantly inhibited plant growth, and this was significantly ameliorated by Spd. The mass of the shoots and roots, content of chlorophyll a and chlorophyll b, root activity, and K+ content were higher whereas Na+ content, Na+/K+ ratio, relative electrolyte leakage, glutathione content, H2O2 content, activity of glutathione reductase (GR), and catalase (CAT) were lower after application of Spd in comparison with NaCl alone. The expression of GR, ascorbate peroxidase, CAT, and superoxide dismutase genes also significantly decreased in salt stressed plants with Spd. This study has proved the role of Spd in alleviating salt stress in foxtail millet and identified that 20 μM Spd was most effective.

Keywords

• antioxidant enzymes
• gene expression
• reactive oxygen species
• root activity
• soil salinity