Pedosphere 28(6): 926--942, 2018
ISSN 1002-0160/CN 32-1315/P
©2018 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Mechanisms of exogenous nitric oxide and 24-epibrassinolide alleviating chlorosis of peanut plants under iron deficiency
SONG Yiling1, DONG Yuanjie1, TIAN Xianyi1, WANG Wanwan1, Zhenli HE2
1College of Resources and Environment, National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer, Shandong Agricultural University, Tai'an 271018(China);
2Indian River Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Fort Pierce FL 34945(USA)
      Iron (Fe) is a crucial transition metal for all living organisms including plants; however, Fe deficiency frequently occurs in plant because only a small portion of Fe is bioavailable in soil in recent years. To cope with Fe deficiency, plants have evolved a wide range of adaptive responses from changes in morphology to altered physiology. To understand the role of nitric oxide (NO) and 24-epibrassinolide (EBR) in alleviating chlorosis induced by Fe deficiency in peanut (Arachis hypogaea L.) plants, we determined the concentration of chlorophylls, the activation, uptake, and translocation of Fe, the activities of key enzymes, such as ferric-chelate reductase (FCR), proton-translocating adenosine triphosphatase (H+-ATPase), and antioxidant enzymes, and the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) of peanut plants under Fe sufficiency (100 µmol L-1 ethylenediaminetetraacetic acid (EDTA)-Fe) and Fe deficiency (0 µmol L-1 EDTA-Fe). We also investigated the production of NO in peanut plants subjected to Fe deficiency with foliar application of sodium nitroprusside (SNP), a donor of NO, and/or EBR. The results showed that Fe deficiency resulted in severe chlorosis and oxidative stress, significantly decreased the concentration of chlorophylls and active Fe, and significantly increased NO production. Foliar application of NO and/or EBR increased the activity of antioxidant enzymes, superoxide dismutase, peroxidase, and catalase, and decreased the ROS and MDA concentrations, thus enhancing the resistance of plants to oxidative stress. Application of NO also significantly increased Fe translocation from the roots to the shoots and enhanced the transfer of Fe from the cell wall fraction to the cell organelle and soluble fractions. Consequently, the concentrations of available Fe and chlorophylls in the leaves were elevated. Furthermore, the activities of H+-ATPase and FCR were enhanced in the Fe-deficient plants. Simultaneously, there was a significant increase in NO production, especially in the plants that received NO, regardless of Fe supply. These suggest that NO or EBR, and, especially, their combination are effective in alleviating plant chlorosis induced by Fe deficiency.
Key Words:  active iron,antioxidant enzyme,subcellular structure,chlorophyll,oxidative stress,reactive oxygen species,sodium nitroprusside
Citation: Song Y L, Dong Y J, Tian X Y, Wang W W, He Z. 2018. Mechanisms of exogenous nitric oxide and 24-epibrassinolide alleviating chlorosis of peanut plants under iron deficiency. Pedosphere. 28(6):926-942.
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