Enhanced Net K⁺ Uptake Capacity of NaCl-Adapted Cells

Abstract

Maintenance of intracellular K+ concentrations that are not growth-limiting, in an environment of high Na+, is characteristic of NaCI-adapted cells of the glycophyte, tobacco (Nicotiana tabacum/gossii). These cells exhibited a substantially greater uptake of "Rb+ (i.e. an indicator of K+) relative to unadapted cells.Potassium uptake into NaCI-adapted cells was 1.5-fold greater than unadapted cells at 0 NaCI and 3.5-fold greater when cells were exposed to 160 millimolar NaCI. The difference in net K+ uptake between unadapted and NaCI-adapted cells was due primarily to higher rates of entry rather than to reduced K+ leakage. Presumably, enhanced K+ uptake into adapted cells is a result of electrophoretic flux, and a component of uptake may be linked to vanadate-sensitive H+ extrusion.

Growth, water status and nutrient accumulation of seedlings of Holoptelea integrifolia (Roxb.) Planch in response to soil salinity

“…Plants utilize two systems for K acquisition, low-and high-affinity uptake mechanisms. Low affinity of K uptake is not inhibited by Na but the high affinity process is restricted (Watad et al 1991). Similarly Na toxicity in plants is correlated with two proposed Na uptake pathways (Niu et al 1995).…”

“…An increase of K content in leaves in response to salinity evinces an enhanced transport of K from stem tissues to protect leaves. It is reported that uptake mechanisms of both K and Na are similar (Watad et al 1991). Plants utilize two systems for K acquisition, low-and high-affinity uptake mechanisms.…”

Sodium as nutrient and toxicant

“…The potassium target A large number of studies has shown the disruption of both cellular and whole-plant potassium homeostasis under sodium stress (Rains and Epstein 1967a, b, c;Flowers and Läuchli 1983;Watad et al 1991;Gaxiola et al 1992;Warne et al 1996;Zhu et al 1998 Takahashi et al 2007;Kronzucker et al 2008;Britto et al 2010;Coskun et al 2013, cf. Seemann andCritchley 1985).…”

Combination effect of NaCl salinity, nitrogen form and calcium concentration on the growth, ionic content and gaseous exchange properties of Triticum aestivum L. cv. Gamtoos

“…Sodium ions apparently nonsaline conditions but there is also evidence to compete with Ca^^ for uptake (Lynch, Cramer & indicate that it affects salinity tolerance under certain and/or affect intracellular levels of conditions (Lewis, Leidi & Lips, 1989), This could Ca^+ (Lynch & Lauchli, 1988;Lynch, Polito & be due to the fact that uptake and assimilation of Lauchli, 1989); Na+ also mcreases membrane NO3" and NH4+ have different energy requirements porosity (Van Steveninck, 1965, Watad et al, 1991 (Clarkson, 1986) and to interaction between NaCl and results in membrane depolarization (Lauchli, and nitrogen ion uptake. Since many natural and 1990), allowing the leakage of some ions and an agricultural lands which are saline are also N poor mflux of others.…”