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

CHUN-MEI WANG; JIN-LIN ZHANG; XUE-SONG LIU; ZHAN LI; GUO-QIANG WU; JIAN-YI CAI; FLOWERS, TIMOTHY J.; SUO-MIN WANG

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.

PUCCINELLIA; GRASSES; SALT; BIOLOGICAL transport; EXCRETION; OSMOSIS; ABSORPTION (Physiology)

Plant, Cell & Environment, 2009, Vol 32, Issue 5, p486

0140-7791

Academic Journal

10.1111/j.1365-3040.2009.01942.x