The mechanistic basis of sodium exclusion in?Puccinellia tenuiflora?under conditions of soil salinity and potassium deprivation

发布时间:2022-09-05 字体大小 T |T

Title: The mechanistic basis of sodium exclusion in Puccinellia tenuiflora under conditions of soil salinity and potassium deprivation

Authors: Qing-Qing Han, Yong-Ping Wang, Jian Li, Jing Li, Xiao-Chang Yin, Xing-Yu Jiang, Min Yu, Suo-Min Wang, Sergey Shabala*, Jin-Lin Zhang*

Journal: The Plant Journal

Impact Factor: IF2021 = 7.09

Abstract: Soil salinity is a significant threat to global agriculture. Understanding salt-exclusion mechanisms in halophyte species may be instrumental in improving salt tolerance in crops. Puccinellia tenuiflora is a typical salt-excluding halophytic grass often found in potassium-deprived saline soils. Our previous work showed P. tenuiflora possesses stronger selectivity for K+ over Na+; however, the mechanistic basis of this process remained elusive. Here, P. tenuiflora PutHKT1;5 was cloned and the functions of PutHKT1;5 and PutSOS1 were characterized using heterologous expression systems. Yeast assays showed PutHKT1;5 possessed Na+ transporting capacity and was highly selective for Na+ over K+. PutSOS1 was located at the plasma membrane and operated as Na+/K+ exchanger, with much stronger Na+ extrusion capacity than its homolog from Arabidopsis. PutHKT2;1 mediated high-affinity K+ and Na+ uptake and its expression levels were up-regulated by mild salinity and K+ deprivation. Salinity-induced changes of root PutHKT1;5 and PutHKT1;4 transcript levels matched the expression pattern of root PutSOS1 that was consistent with root Na+ efflux. The transcript levels of root PutHKT2;1 and PutAKT1 were down-regulated by salinity. Taken together, these findings demonstrate that the functional activity of PutHKT1;5 and PutSOS1 in P. tenuiflora roots is fine-tuned under saline conditions as well as by operation of other ion-transporters (PutHKT1;4, PutHKT2:1 and PutAKT1). This leads to the coordination of radial Na+ and K+ transport processes, their loading to the xylem, or Na+ retrieval and extrusion under conditions of mild salinity and / or K+ deprivation.