Puccinellia tenuiflora maintains a low Na+ level under salinity by limiting unidirectional Na+ influx resulting in a high selectivity for K+ over Na+.
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.
Wang
Chun-Mei
CM
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
Zhang
Jin-Lin
JL
Liu
Xue-Song
XS
Li
Zhan
Z
Wu
Guo-Qiang
GQ
Cai
Jian-Yi
JY
Flowers
Timothy J
TJ
Wang
Suo-Min
SM
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
D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium