title: ZxAKT1 is essential for K+uptake and K+/Na+homeostasis in the succulent xerophyte Zygophyllum xanthoxylum.
abstract: The inward-rectifying K+channel AKT1 constitutes an important pathway for K+acquisition in plant roots. In glycophytes, excessive accumulation of Na+is accompanied by K+deficiency under salt stress. However, in the succulent xerophyte Zygophyllum xanthoxylum, which exhibits excellent adaptability to adverse environments, K+concentration remains at a relatively constant level despite increased levels of Na+under salinity and drought conditions. In this study, the contribution of ZxAKT1 to maintaining K+and Na+homeostasis in Z. xanthoxylum was investigated. Expression of ZxAKT1 rescued the K+-uptake-defective phenotype of yeast strain CY162, suppressed the salt-sensitive phenotype of yeast strain G19, and complemented the low-K+-sensitive phenotype of Arabidopsis akt1 mutant, indicating that ZxAKT1 functions as an inward-rectifying K+channel. ZxAKT1 was predominantly expressed in roots, and was induced under high concentrations of either KCl or NaCl. By using RNA interference technique, we found that ZxAKT1-silenced plants exhibited stunted growth compared to wild-type Z. xanthoxylum. Further experiments showed that ZxAKT1-silenced plants exhibited a significant decline in net uptake of K+and Na+, resulting in decreased concentrations of K+and Na+, as compared to wild-type Z. xanthoxylum grown under 50 mm NaCl. Compared with wild-type, the expression levels of genes encoding several transporters/channels related to K+/Na+homeostasis, including ZxSKOR, ZxNHX, ZxSOS1 and ZxHKT1;1, were reduced in various tissues of a ZxAKT1-silenced line. These findings suggest that ZxAKT1 not only plays a crucial role in K+uptake but also functions in modulating Na+uptake and transport systems in Z. xanthoxylum, thereby affecting its normal growth.
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Xiang-Rui
authors.initials: XR
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Hui-Jun
authors.initials: HJ
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Tanweer
authors.initials: T
authors.lastname: Kumar
authors.affiliation: Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA, 73072, USA.|NJU-NJFU Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing, 210093, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Luan
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Suo-Min
authors.initials: SM
authors.lastname: Wang
mesh_terms: D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D010940:Plant Proteins / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D032445:Zygophyllum / Q000187:drug effects / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D012965:Sodium Chloride; D011189:Potassium Chloride; D012964:Sodium; D011188:Potassium
keywords: 
  Zygophyllum xanthoxylum
  ; K+ uptake; K+/Na+ homeostasis; ZxAKT1; salinity