Exogenous mammalian sex hormones mitigate inhibition in growth by enhancing antioxidant activity and synthesis reactions in germinating maize seeds under salt stress.

BACKGROUND: Mammalian sex hormones (MSH)-progesterone, β-estradiol and androsterone-enhance plant growth and development by stimulating significant morphological and biochemical parameters under normal conditions. However, there is no report regarding their effects on plants exposed to environmental stress conditions. Therefore, the present study was focused on elucidating the possible positive effects of MSH on seedling growth, antioxidant activity and synthesis reactions in maize seeds exposed to salt stress, one of the most important environmental stresses. For this purpose, the various concentrations (10⁻⁶, 10⁻⁸, 10⁻¹⁰ and 10⁻¹² mol L⁻¹) of MSH were studied.

RESULTS: Salinity (100 mmol L⁻¹ NaCl) significantly reduced root length and seedling height, whereas MSH treatment significantly ameliorated the adverse effects of salinity on root length and seedling height. On the other hand, although salinity increased soluble protein, soluble sugar and proline content in 7-day-old maize seedlings, these were higher in MSH-treated seedlings. Similarly, MSH treatment augmented superoxide dismutase, peroxidase and catalase activities under salt stress, whereas it decreased superoxide production and lipid peroxidation level. The most favorable concentrations were determined as 10⁻⁸ mol L⁻¹ for progesterone and β-estradiol and 10⁻¹⁰ mol L⁻¹ for androsterone.

CONCLUSION: Exogenous MSH application was found to have an important ameliorative effect on growth of seeds exposed to salt stress by stimulating antioxidant activity and synthesis reactions. This is the first study investigating the effects of MSH on germination of seeds exposed to stress conditions.