In plants, K transporter (KT)/high affinity (HAK)/K uptake permease (KUP) is the largest potassium (K) family; however, few of members have had their physiological functions characterized in planta. Here, we studied OsHAK5 KT/HAK/KUP family rice (Oryza sativa). We determined its cellular and tissue localization analyzed using both knockout mutants overexpression lines three genetic backgrounds. A β-glucuronidase reporter driven by native promoter indicated expression various organs from root...

Leaf-moving organs, remarkable for the rhythmic volume changes of their motor cells, served as a model system in which to study regulation membrane water fluxes. Two plasma intrinsic protein homolog genes, SsAQP1 and SsAQP2, were cloned from these organs characterized aquaporins Xenopus laevis oocytes. Osmotic permeability (Pf) was 10 times higher SsAQP2-expressing oocytes than SsAQP1-expressing found be glycerol permeable, SsAQP2 inhibited by 0.5 mM HgCl2 1 phloretin. The aquaporin mRNA...

We present the first evidence for a fast activation of nuclear protein poly(ADP-ribose) polymerase (PARP) by signals evoked in cell membrane, constituting novel mode signaling to nucleus. PARP, an abundant, highly conserved, chromatin-bound found only eukaryotes, exclusively catalyzes polyADP-ribosylation DNA-binding proteins, thereby modulating their activity. Activation reportedly induced formation DNA breaks, is involved transcription, replication, and repair. Our findings demonstrate...

Leaflet movements in Samanea saman are driven by the shrinking and swelling of cells opposing (extensor flexor) regions motor organ (pulvinus). Changes cell volume, turn, depend upon large changes content K(+), Cl(-) other ions. We performed patch-clamp experiments on extensor flexor protoplasts, to determine whether their plasma membranes contain channels capable carrying K(+) currents that flow during leaflet movement. Recordings "whole-cell" mode reveal depolarization-activated increase...

Plant HAK/KUP/KT family members function as plasma membrane (PM) H+/K+ symporters and may modulate chemiosmotically-driven polar auxin transport (PAT). Here, we show that inactivation of OsHAK5, a rice K+ transporter gene, decreased rootward shootward PAT, tiller number, the length both lateral roots root hairs, while OsHAK5 overexpression increased hair length, irrespective supply. Inhibitors ATP-binding-cassette type-B transporters, NPA BUM, abolished OsHAK5-overexpression effect on PAT....

Abstract Alder (Alnus glutinosa) and more than 200 angiosperms that encompass 24 genera are collectively called actinorhizal plants. These plants form a symbiotic relationship with the nitrogen-fixing actinomycete Frankia strain HFPArI3. The provide bacteria carbon sources in exchange for fixed nitrogen, but this metabolite nodules has not been well defined. We isolated an alder cDNA from nodule library by differential screening versus root found it encoded transporter of PTR (peptide...

Abstract In a search for potassium channels involved in light- and clock-regulated leaf movements, we cloned four putative K channel genes from the leaf-moving organs, pulvini, of legume Samanea saman. The S. saman SPOCK1 is homologous to KCO1, an Arabidopsis two-pore-domain channel, SPORK1 similar SKOR GORK, outward-rectifying Shaker-like channels, theS. SPICK1 SPICK2 are AKT2, weakly-inward-rectifying channel. All sequences possess universal K-channel-specific pore signature, TXXTXGYG,...

The patch-clamp technique was used to study passive movements of ions through the plasmalemma wheat leaf protoplasts. This method overcomes problems inherent in conventional electrophysiological plant cells. Changes conductance were recorded patches excised from plasmalemma. Two types observed: (i) regions low channel density, where discrete single-channel currents could be resolved and ranged 10 200 picosiemens (ii) high not on order a few nanosiemens. results indicate striking similarity...

We have studied the effects of batrachotoxin (BTX) on sodium channels in hybrid mouse neuroblastoma cells NG108-15 by using suction pipet voltage clamp method. BTX-modified activate with first-order kinetics and, over most potential range, more slowly than normal channels. The peak conductance-voltage curve and time constant activation-versus-voltage for are shifted about 50 mV hyperpolarizing direction compared to corresponding curves There is no change slope curve. These results suggest...

High-affinity potassium (K+) transporter (HAK)/K+ uptake permease (KUP)/K+ (KT) have been identified in all genome-sequenced terrestrial plants. They play an important role K+ acquisition and translocation enhancing salt tolerance. Here, we report that plasma membrane-located OsHAK18 functions sodium (Na+) circulation sugar rice (Oryza sativa). was expressed mainly, though not exclusively, vascular tissues particularly the phloem. Knockout (KO) of reduced concentration phloem sap roots but...

Abstract The osmotic water permeability coefficient (Pf) of plasma membrane maize (Zea mays) Black Mexican Sweet protoplasts changed dynamically during a hypoosmotic challenge, as revealed using model-based computational approach. best-fitting model had three free parameters: initial Pf, Pf rate-of-change (slopePf), and delay, which were hypothesized to reflect changes in the number and/or activity aquaporins membrane. Remarkably, swelling response was delayed 2 11 s after start...

Abstract Leaflet movements in the legume Samanea saman are under joint control by light and a circadian oscillator. The driven massive fluxes of K + , Cl − H through pulvinar motor cell membranes. Light oscillator affect leaflet altering activity ion transport systems. Some effects on may be mediated phosphatidylinositol (PI) cycle, since brief irradiation pulvinus with white accelerates PI turnover.

The leaf vascular bundle sheath cells (BSCs) that tightly envelop the veins, are a selective and dynamic barrier to xylem sap water solutes radially entering mesophyll cells. Under normal conditions, pH below 6 is presumably important for driving regulating transmembranal solute transport. Having discovered recently differentially high expression of BSC proton pump, AHA2, we now test hypothesis it regulates radial fluxes. We monitored in veins detached leaves wild-type Arabidopsis, AHA...

A depolarization-activated K(+) channel capable of carrying the large currents that flow from shrinking cells during movements Samanea saman leaflets has been described in plasmalemma motor cell protoplasts (N Moran et al [1988] Plant Physiol 88:643-648). We now characterize this greater detail. It is selective for over other monovalent ions, with following order relative permeability: > Rb(+) Na(+) approximately Cs(+) Li(+). blocked by and Ba(2+) a voltage dependent manner, exhibiting...

Cadmium causes the generation of reactive oxygen species, which in turn cell damage. We isolated a novel gene from wheat root cDNA library, conferred Cd(II)-specific tolerance when expressed yeast (Saccharomyces cerevisiae). The gene, we called TaTM20, for Triticum aestivum transmembrane 20, encodes putative hydrophobic polypeptide 889 amino acids, containing 20 domains arranged as 5-fold internal repeating unit 4 each. Expression TaTM20 cells stimulated Cd(II) efflux resulting decrease...

Abstract Light-induced leaflet movement of Samanea samandepends on the regulation membrane transporters in motor cells. Blue light (BL) stimulates opening by inducing K+release from flexor To elucidate mechanism K+-efflux (KD)-channel light, cell protoplasts were patch-clamped a cell-attached configuration during varying illumination. Depolarization elicited outward currents through single open KD channels. Changes potential (E M) estimated applying voltage ramps and tracking change apparent...

Previous studies reveal that the pH of apoplastic solution in guard cell walls may vary between 7.2 and 5.1 closed open stomata, respectively. During these aperture changes, massive K+ fluxes cross cellular plasma membrane driving osmotic turgor volume changes cells. Therefore, we examined effect extracellular on depolarization-activated K channels (KD channels), which constitute efflux pathway, Vicia faba protoplasts. We used patch clamp, both whole cells as well excised outside-out...

The use of patch clamp methods for identifying ion‐specific channels and other transport structures in plant cell membranes is described. Methodology, basic concepts that underlie data analysis, applications this powerful technique are emphasized.

Abstract In the animal world, regulation of ion channels by phosphoinositides (PIs) has been investigated extensively, demonstrating a wide range controlled phosphatidylinositol (4,5)bisphosphate (PtdInsP2). To understand PI plant channels, we examined in planta effect PtdInsP2 on K+-efflux channel tobacco (Nicotiana tabacum), NtORK (outward-rectifying K channel). We applied patch clamp whole-cell configuration (with fixed “cytosolic” Ca2+ concentration and pH) to protoplasts isolated from...

Under fluctuating ambient conditions, the ability of plants to maintain hydromineral homeostasis requires tight control long distance transport. This includes radial transport within leaves, from veins mesophyll. The bundle sheath is a structure that tightly wraps around leaf vasculature. It has been suggested act as selective barrier in context suggestion based on recent physiological assays cells (BSCs), well anatomy these cells.We hypothesized unique functionality BSCs apparent their...

We used the patch-clamp technique to examine effect of temperature (13-36[deg]C) on depolarization-activated K channels (KD channels) and hyperpolarization-activated (KH in plasma membrane Vicia faba guard-cell protoplasts. The steady-state whole-cell conductance both channel types increased with up 20[deg]C. However, whereas KH further saturated at 28[deg]C, that KD decreased higher temperatures. unitary like rate diffusion water (temperature quotient approximately 1.5), constituting major...