title: Puccinellia tenuiflora maintains a low Na+ level under salinity by limiting unidirectional Na+ influx resulting in a high selectivity for K+ over Na+.
abstract: Puccinellia tenuiflora is a useful monocotyledonous halophyte that might be used for improving salt tolerance of cereals. This current work has shown that P. tenuiflora has stronger selectivity for K+ over Na+ allowing it to maintain significantly lower tissue Na+ and higher K+ concentration than that of wheat under short- or long-term NaCl treatments. To assess the relative contribution of Na+ efflux and influx to net Na+ accumulation, unidirectional 22Na+ fluxes in roots were carried out. It was firstly found that unidirectional 22Na+ influx into root of P. tenuiflora was significantly lower (by 31-37%) than in wheat under 100 and 150 mM NaCl. P. tenuiflora had lower unidirectional Na+ efflux than wheat; the ratio of efflux to influx was similar between the two species. Leaf secretion of P. tenuiflora was also estimated, and found the loss of Na+ content from leaves to account for only 0.0006% of the whole plant Na+ content over 33 d of NaCl treatments. Therefore, it is proposed that neither unidirectional Na+ efflux of roots nor salt secretion by leaves, but restricting unidirectional Na+ influx into roots with a strong selectivity for K+ over Na+ seems likely to contribute to the salt tolerance of P. tenuiflora.
authors.affiliation: Key Laboratory of Grassland Agro-ecosystem, Ministry of Agriculture, School of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China. smwang@lzu.edu.cn
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Wang
authors.forename: Jin-Lin
authors.initials: JL
authors.lastname: Zhang
authors.forename: Xue-Song
authors.initials: XS
authors.lastname: Liu
authors.forename: Zhan
authors.initials: Z
authors.lastname: Li
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Wu
authors.forename: Jian-Yi
authors.initials: JY
authors.lastname: Cai
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Flowers
authors.forename: Suo-Min
authors.initials: SM
authors.lastname: Wang
mesh_terms: D001692:Biological Transport; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D055051:Salt-Tolerant Plants / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D014908:Triticum / Q000254:growth & development / Q000378:metabolism
chemical_list: D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium