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A greenhouse hydroponic experiment was performed to evaluate how peanut seedlings ( Arachis hypogaea L.) responded to iron (Fe) deficiency stress in the presence of sodium nitroprusside (SNP), a nitric oxide (NO) donor. The results showed that Fe deficiency inhibited peanut plant growth, decreased chlorophyll and active Fe concentrations, and dramatically disturbed ion balance. The addition of 50, 100, 250, and 500 µM SNP, significantly promoted the absorption of Fe in the cell wall, cell organelles, and soluble fractions, increased the concentrations of active Fe and chlorophyll in peanut plants, and alleviated the excess absorption of manganese (Mn) and copper (Cu) induced by Fe deficiency. In addition, SNP also significantly increased the activities of superoxide dismutase, peroxidase, and catalase, which is beneficial to inhibit the accumulation of malondialdehyde and reactive oxygen species. Addition of 250 µM SNP had the most significant alleviating effect against Fe-deficiency stress, and after 15 days of treatment, the plants with the 250 µM SNP treatment achieved comparable NO levels with those grown under optimal nutrition conditions. However, the effects of SNP were reversed by addition of hemoglobin (Hb, a NO scavenger). These results suggest that NO released from SNP decomposition was responsible for the effect of SNP-induced alleviation on Fe deficiency. [ABSTRACT FROM AUTHOR]

The effects of salicylic acid (SA) on alleviating chlorosis induced by iron (Fe) deficiency in peanut seedlings ( Arachis hypogaea L.) were studied by investigating the symptoms, plant growth, chlorophyll concentrations, soluble Fe concentration, Fe distribution in subcellular, and antioxidant enzymes. Fe deficiency caused serious chlorosis and inhibited growth of peanut seedlings, and dramatically decreased the soluble Fe concentration and chlorophyll concentration. Furthermore, ion balance was disturbed. The addition of 50, 100, and 250 μM SA significantly increased the absorption of Fe from the cell wall to cell organelles and the soluble fraction, enhanced the Fe concentration in cell organelles, Fe activation and chlorophyll concentrations in leaves, ameliorated the inhibition of Ca, Mg, and Zn absorption induced by Fe deficiency, alleviated the chlorosis induced by Fe deficiency and promoted plant growth. The accumulation of reactive oxygen species (ROS) is dramatically increased in peanut seedlings exposed to Fe deficiency, and resulted in lipid peroxidation, which was indicated by accumulation of malondialdehyde (MDA). The application of 50, 100, and 250 μM SA significantly decreased the level of ROS and MDA concentrations, and significantly increased the activities of superoxide dismutase, peroxidase, and catalase in peanut seedlings exposed to Fe deficiency. The addition of 100 μM SA had the best effect on alleviating chlorosis induced by Fe deficiency, whereas the addition of 500 μM SA had no significant effect under Fe deficiency. [ABSTRACT FROM AUTHOR]