Alleviation of chromium toxicity by trehalose supplementation in Zea mays through regulating plant biochemistry and metal uptake

Exogenously applied trehalose is effective for improving plant tolerance to some abiotic stresses, but whether it has function in alleviating maize (Zea mays) tolerance to chromium (Cr) stress is unknown. This study investigated the effects of exogenous application of trehalose (0, 25 and 50 mM) on the growth, physiological parameters and oxidative defense systems of maize seedlings exposed to chromium (Cr) stress at the rate of 100 and 500 mu M. Our results depicted that Cr stress reduced plant growth, biomass, leaf chlorophyll contents, transpiration rate, photosynthetic properties, stomatal conductance and antioxidant enzymes. The Cr-induced increase was observed in oxidative defense system, malondialdehyde, hydrogen peroxide contents and membrane leakage. Although, activities of POD, SOD and CAT enzymes, total phenolics and proline concentrations increased at 100 mu M Cr but were significantly diminished at 500 mu M compared to non-Cr plants. However, the negative impacts of Cr on plant growth and physiological traits were reduced by the foliar application of trehalose. Trehalose significantly enhanced plant biomass, improved photosynthetic apparatus and antioxidants in addition to ascorbic acid, free proline, GB and total phenolic compounds. The application of trehalose diminished the exudation of organic acids and indicator of oxidative stress in roots and shoots by decreasing Cr retention in plant parts. The findings suggest that 50 mM trehalose spray efficiently mitigated the Cr toxicity in maize plants as compared to 25 m trehalose spray. However, the exogenous application of trehalose alleviated Cr toxicity by regulating Cr uptake in plant tissues by enhancing the antioxidative defense system.