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Front. Plant Sci. | doi: 10.3389/fpls.2018.00256

Melatonin-stimulated triacylglycerol breakdown and energy turnover under salinity stress contributes to the maintenance of plasma membrane H+–ATPase activity and K+/Na+ homeostasis in sweet potato

Yicheng Yu1,  Aimin Wang1, Xiang Li1, Meng Kou2, Wenjun Wang3, Xianyang Chen3, Tao Xu1, Mingku Zhu1, Daifu Ma3,  Zongyun Li1 and  Jian Sun1*
  • 1School of Life Sciences, Jiangsu Normal University, China
  • 2Xuzhou Institute of Agricultural Sciences (CAAS), China
  • 3Beijing Qiji Biotechnology Co., Ltd, China

Melatonin (MT) is a multifunctional molecule in animals and plants and is involved in defense against salinity stress in various plant species. In this study, MT pretreatment was simultaneously applied to the roots and leaves of sweet potato seedlings (Ipomoea batatas (L.) Lam.), which is an important food and industry crop worldwide, followed by treatment of 150 mM NaCl. The roles of MT in mediating K+/Na+ homeostasis and lipid metabolism in salinized sweet potato were investigated. Exogenous MT enhanced the resistance to NaCl and improved K+/Na+ homeostasis in sweet potato seedlings as indicated by the low reduced K+ content in tissues and low accumulation of Na+ content in the shoot. Electrophysiological experiments revealed that exogenous MT significantly suppressed NaCl-induced K+ efflux in sweet potato roots and mesophyll tissues. Further experiments showed that MT enhanced the plasma membrane (PM) H+–ATPase activity and intracellular adenosine triphosphate (ATP) level in the roots and leaves of salinized sweet potato. Lipidomic profiling revealed that exogenous MT completely prevented salt-induced triacylglycerol (TAG) accumulation in the leaves. In addition, MT upregulated the expression of genes related to TAG breakdown, fatty acid (FA) β-oxidation, and energy turnover. Chemical inhibition of the β-oxidation pathway led to drastic accumulation of lipid droplets in the vegetative tissues of NaCl-stressed sweet potato and simultaneously disrupted the MT-stimulated energy state, PM H+–ATPase activity, and K+/Na+ homeostasis. Results revealed that exogenous MT stimulated TAG breakdown, FA β-oxidation, and energy turnover under salinity conditions, thereby contributing to the maintenance of PM H+–ATPase activity and K+/Na+ homeostasis in sweet potato.

Keywords: Melatonin, Sweet potato, K+/Na+ homeostasis, triacylglycerol, FATTY ACID β-OXIDATION, PM H+–ATPase

Received: 12 Sep 2017; Accepted: 12 Feb 2018.

Edited by:

Vasileios Fotopoulos, Cyprus University of Technology, Cyprus

Reviewed by:

Mirza Hasanuzzaman, Sher-e-Bangla Agricultural University, Bangladesh
Baris Uzilday, Ege University, Turkey  

Copyright: © 2018 Yu, Wang, Li, Kou, Wang, Chen, Xu, Zhu, Ma, Li and Sun. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Jian Sun, Jiangsu Normal University, School of Life Sciences, Shanghai Road 101, Tongshan New District, Xuzhou, 221116, Jiangsu, China,