Puccinellia tenuiflora maintains a low Na⁺ level under salinity by limiting unidirectional Na⁺ influx resulting in a high selectivity for K⁺ over Na

• Published in: Plant, cell and environment cell and environment, 2009-05, Vol.32 (5), p.486-496
• Main Authors: WANG, CHUN-MEI, ZHANG, JIN-LIN, LIU, XUE-SONG, LI, ZHAN, WU, GUO-QIANG, CAI, JIAN-YI, FLOWERS, TIMOTHY J, WANG, SUO-MIN
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biological Transport; Fundamental and applied biological sciences. Psychology; Na+secretion; Plant Leaves - metabolism; Plant Roots - metabolism; Poaceae - growth & development; Poaceae - metabolism; Potassium - metabolism; Salt-Tolerant Plants - metabolism; selective absorption for K+ over Na+; selective transport for K+ over Na+; Sodium - metabolism; Sodium Chloride - pharmacology; Triticum - growth & development; Triticum - metabolism; unidirectional 22Na+ influx and efflux
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2009.01942.x

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 m m 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.