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Humic Acid Confers HIGH-AFFINITY K+ TRANSPORTER 1-Mediated Salinity Stress Tolerance in Arabidopsis

  • Khaleda, Laila (Division of Applied Life Science (BK21Plus), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Life Sciences (RILS), Gyeongsang National University) ;
  • Park, Hee Jin (Institute of Glocal Disease Control, Konkuk University) ;
  • Yun, Dae-Jin (Department of Biomedical Science and Engineering, Konkuk University) ;
  • Jeon, Jong-Rok (Department of Agriculture Chemistry and Food Science & Technology, Institute of Agriculture and Life Science (IALS), Gyeongsang National University) ;
  • Kim, Min Gab (College of Pharmacy and Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University) ;
  • Cha, Joon-Yung (Division of Applied Life Science (BK21Plus), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Life Sciences (RILS), Gyeongsang National University) ;
  • Kim, Woe-Yeon (Division of Applied Life Science (BK21Plus), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Life Sciences (RILS), Gyeongsang National University)
  • Received : 2017.09.25
  • Accepted : 2017.11.05
  • Published : 2017.12.31

Abstract

Excessive salt disrupts intracellular ion homeostasis and inhibits plant growth, which poses a serious threat to global food security. Plants have adapted various strategies to survive in unfavorable saline soil conditions. Here, we show that humic acid (HA) is a good soil amendment that can be used to help overcome salinity stress because it markedly reduces the adverse effects of salinity on Arabidopsis thaliana seedlings. To identify the molecular mechanisms of HA-induced salt stress tolerance in Arabidopsis, we examined possible roles of a sodium influx transporter HIGH-AFFINITY $K^+$ TRANSPORTER 1 (HKT1). Salt-induced root growth inhibition in HKT1 overexpressor transgenic plants (HKT1-OX) was rescued by application of HA, but not in wild-type and other plants. Moreover, salt-induced degradation of HKT1 protein was blocked by HA treatment. In addition, the application of HA to HKT1-OX seedlings led to increased distribution of $Na^+$ in roots up to the elongation zone and caused the reabsorption of $Na^+$ by xylem and parenchyma cells. Both the influx of the secondary messenger calcium and its cytosolic release appear to function in the destabilization of HKT1 protein under salt stress. Taken together, these results suggest that HA could be applied to the field to enhance plant growth and salt stress tolerance via post-transcriptional control of the HKT1 transporter gene under saline conditions.

Acknowledgement

Supported by : National Research Foundation of Korea (NRF), Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (IPET)

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