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. 1985 Nov;79(3):771–776. doi: 10.1104/pp.79.3.771

Potassium Transport in Corn Roots 1

IV. Characterization of the Linear Component

Leon V Kochian 1, Jiao Xin-Zhi 1,2, William J Lucas 1
PMCID: PMC1074969  PMID: 16664490

Abstract

A detailed examination was conducted on the linear, or first-order kinetic component for K+(86Rb+) influx into root segments of both low- and high-salt grown corn seedlings (Zea mays [A632 × Oh 43]). In tissue from both low- and high-salt grown roots, replacement of Cl− in the uptake solution by either SO42−, H2PO4−, or NO3− caused a significant (50-60%) and specific inhibition of the linear component of K+ influx. The anion transport inhibitor, 4,4′-diisothiocyano-2,2′-disulfonic acid, was found to abolish saturable Cl− influx in corn roots while causing a significant (50-60%) and specific inhibition of the linear K+ uptake system; this inhibition was identical to that observed when Cl− was replaced by other anions in the K+ uptake solution. Additionally, the quaternary ammonium cation, tetraethylammonium, which has been shown to block K+ channels in nerve axons, also caused a dramatic (70%) and specific inhibition of the linear component of K+ influx, but this was obtained only in high-salt roots. The reasons for this difference are discussed with respect to the differing abilities of low- and high-salt roots to absorb tetraethylammonium.

Our present results indicate that the linear component of K+ influx may occur by a passive process involving transmembrane K+ channels. Fluxes through these K+ channels may be partly coupled to a saturating Cl− influx mechanism.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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