+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Nonselective currents and channels in plasma membranes of protoplasts from coats of developing seeds of bean



Nonselective currents and channels in plasma membranes of protoplasts from coats of developing seeds of bean



Plant Physiology 128(2): 388-399



In developing bean (Phaseolus vulgaris) seeds, phloem-imported nutrients move in the symplast from sieve elements to the ground parenchyma cells where they are transported across the plasma membrane into the seed apoplast. To study the mechanisms underlying this transport, channel currents in ground parenchyma protoplasts were characterized using patch clamp. A fast-activating outward current was found in all protoplasts, whereas a slowly activating outward current was observed in approximately 25% of protoplasts. The two currents had low selectivity for univalent cations, but the slow current was more selective for K(+) over Cl(-) (P(K):P(Cl) = 3.6-4.2) than the fast current (P(K):P(Cl) = 1.8-2.5) and also displayed Ca(2+) selectivity. The slow current was blocked by Ba(2+), whereas both currents were blocked by Gd(3+) and La(3+). Efflux of K(+) from seed coat halves was inhibited 25% by Gd(3+) and La(3+) but was stimulated by Ba(2+) and Cs(+), suggesting that only the fast current may be a component in the pathway for K(+) release. An "instantaneous" inward current observed in all protoplasts exhibited similar pharmacology and permeability for univalent cations to the fast outward current. In outside-out patches, two classes of depolarization-activated cation-selective channels were observed: one slowly activating of low conductance (determined from nonstationary noise to be 2.4 pS) and another with conductances 10-fold higher. Both channels occurred at high density. The higher conductance channel in 10 mM KCl had P(K):P(Cl) = 2.8. Such nonselective channels in the seed coat ground parenchyma cell could function to allow some of the efflux of phloem-imported univalent ions into the seed apoplast.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 003863502

Download citation: RISBibTeXText

PMID: 11842143

DOI: 10.1104/pp.010566


Related references

Nonselective Currents and Channels in Plasma Membranes of Protoplasts from Coats of Developing Seeds of Bean. Plant Physiology 128(2): 388-399, 2002

Mechanisms of solute efflux from seed coats: whole-cell K+ currents in transfer cell protoplasts derived from coats of developing seeds of Vicia faba L. Journal of Experimental Botany 48(313): 1565-1572, 1997

Sodium fluxes through nonselective cation channels in the plasma membrane of protoplasts from Arabidopsis roots. Plant Physiology 128(2): 379-387, 2002

Sodium Fluxes through Nonselective Cation Channels in the Plasma Membrane of Protoplasts from Arabidopsis Roots. Plant Physiology 128(2): 379-387, 2002

Fast activation of a time-dependent outward current in protoplasts derived from coats of developing Phaseolus vulgaris seeds. Planta 211(6): 894-898, 2000

Fast activation of a time-dependent outward current in protoplasts derived from coats of developing Phaseolus vulgaris seeds. Planta 211(6): 894-898, 2000

Aquaporins and unloading of phloem-imported water in coats of developing bean seeds. Plant Cell and Environment 30(12): 1566-1577, 2007

Actin laments modulate hypoosmotic-responsive K+ efflux channels in specialised cells of developing bean seed coats. Functional Plant Biology 34(10): 874-884, 2007

A plasma membrane-enriched fraction isolated from the coats of developing pea seeds contains H(+)-symporters for amino acids and sucrose. Journal of Experimental Botany 51(351): 1671-1677, 2000

Pulsing Cl- channels in coat cells of developing bean seeds linked to hypo-osmotic turgor regulation. Journal of Experimental Botany 55(399): 993, 2004

Skf 96365 blocks agonist induced inward currents through nonselective cation channels in hl 60 cells. Naunyn-Schmiedeberg's Archives of Pharmacology 345(Suppl. 1): R50, 1992

A comparative spin-label study of isolated plasma membranes and plasma membranes of whole cells and protoplasts from cold-hardened and nonhardened winter rye. Plant Physiology 88(4): 1388-1396, 1988

Calcium-dependent K current in plasma membranes of dermal cells of developing bean cotyledons. Plant, Cell and Environment 27(2): 251-262, 2004

Opposing effects of aluminum on inward-rectifier potassium currents in bean root tip protoplasts. Journal of Membrane Biology 198(1): 15-22, 2004

Some properties of an acid phosphatase isolated from the seed coats of developing pea seeds. Annals of Botany 46(5): 499-504, 1980