SsHKT1;1 is coordinated with SsSOS1 and SsNHX1 to regulate Na+ homeostasis in Suaeda salsa under saline conditions

• Published in: Plant and soil Vol. 449; no. 1-2; pp. 117 - 131
• Main Authors: Wang, Wen-Ying, Liu, Ya-Qi, Duan, Hui-Rong, Yin, Xiu-Xia, Cui, Yan-Nong, Chai, Wei-Wei, Song, Xin, Flowers, Timothy J., Wang, Suo-Min
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-04-2020; Springer Nature B.V
• Subjects: Accumulation; Biomedical and Life Sciences; Ecology; Halophytes; Homeostasis; Hydrogen; Leaves; Life Sciences; Membrane proteins; Membranes; Na+/H+-exchanging ATPase; Parenchyma; Plant Physiology; Plant Sciences; Regular Article; Sequestering; Sodium chloride; Soil Science & Conservation; Suaeda salsa; Synergistic effect; Vacuoles; Xylem; Yeasts; Halophyte; Salt tolerance; HKT transporter; Na; accumulation; Collaborative mechanism
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-020-04463-x

Background
Under saline conditions,
Suaeda salsa
, as a typical halophyte, accumulates large amounts of Na
+
in its leaves during optimal growth. Key transporters involved in Na
+
accumulation in plants are HKT-type protein, the plasma membrane Na
+
/H
+
transporter SOS1, and the tonoplast Na
+
/H
+
antiporter NHX1. In this study, the function of SsHKT1;1 and its coordinate expression with SsSOS1 and SsNHX1 to regulate Na
+
homeostasis in
S. salsa
was investigated.
Results
We showed, by yeast complementation assays, that
SsHKT1;1
encoded a Na
+
-selective transporter, which located to the plasma membrane and was preferentially expressed within the stele, and was particularly abundant in xylem parenchyma and pericycle cells. When compared with a treatment of 25 mM NaCl, 150 mM NaCl greatly decreased the transcripts of
SsHKT1;1
, but maintained a relatively constant level of the expression of
SsSOS1
in roots. Consequently, the synergistic effect of SsHKT1;1 and SsSOS1 would result in greater Na
+
loading into the xylem under 150 mM NaCl than 25 mM NaCl. In leaves, 150 mM NaCl up-regulated the abundance of
SsNHX1
compared with levels in 25 mM NaCl. This enabled the permanent sequestering of Na
+
into leaf vacuoles.
Conclusions
Overall, SsHKT1;1 functioned in reducing Na
+
retrieval from the root xylem, and played an important role in coordinating with SsSOS1 and SsNHX1 to maintain Na
+
accumulation in
S. salsa
under saline conditions.