Effects of La3+ on inward K+ channels at plasma membrane in guard cells

Abstract

The effects of La 3+ on inward K + channels at plasma membrane in vicia guard cells are investigated using the whole-cell patch-clamp recording mode. It is shown that La 3+ on both sides of plasma membrane blocks inward K + currents in a concentration-dependent manner, indicating that La 3+ binding sites may exist on both sides of plasma membrane in guard cells in vicia. The dose response is fitted by the Michaelis-Menten relation characterized by an inhibitor constant K i of 2.56±0.25 µmol•L −1 (outside membrane) and (1.18±0.11)×10 −15 mol•L −1 (inside membrane). Intracellular La 3+ has much stronger inhibitory effect on inward K + currents than extracellular La 3+ does, suggesting there may exist stronger binding sites inside membrane than outside membrane. Since ion channel activities of guard cells directly affect plant stomatal movement and water status, our results imply that rare earth elements might have potential practical values in regulating plant water status and strengthening plant drought endurance.

Jasmonic Acid (JA) Acts as a Signal Molecule in LaCl3-Induced Baicalin Synthesis in Scutellaria baicalensis Seedlings

“…REEs have been reported to increase biomass and secondary metabolite synthesis in medicinal plants. Many studies on the physiological effects of REE application have shown that they could improve photosynthesis significantly by promoting the absorption, transfer, and transformation of light energy and photochemical activity in chloroplasts, promote nitrogen metabolism [5][6][7][8][9][10][11], as well as replace calcium in functions such as regulating stomatal movement [12]. However, very few studies have investigated how REEs mediate secondary metabolism synthesis in medicinal plants.…”

Nitric oxide suppresses stomatal opening by inhibiting inward-rectifying K in + channels in Arabidopsis guard cells

“…This phenomenon is similar with the action of ABA on K + in channels. ABA had no effect on K + in channels when Ca 2+ in the pipette solution was chelated [15] ; K + in channels were inhibited by ABA when there was no chelating reagent in pipette solution [23] . There are several reports of NO involving in ABA signaling [24,25] , the similarity of NO and ABA effect on K + in channels prompts that they may share the same target-cytosolic Ca 2+ .…”

“…grown in a controlled environment growth chamber for 4-6 weeks, and guard cell protoplasts were isolated as described [14,15] . In brief, two Arabidopsis rosette leaves (2 cm long) were blended in a blender in cold (4℃) deionized water three times, 20 s each, and collected on a 292-μm mesh.…”

Effects of La3+ and Eu3+ on outward potassium channels in Vicia guard cells

“…We have studied the effects of La 3+ on inward potassium channels (K + in ) in Vicia guard cells previously [6] , the results showed that La 3+ on both sides of the plasma membrane inhibited K + in currents. In the present research, extracellular La 3+ inhibited K + out currents and the half-inhibition concentration (IC 50 ) is 81 μmol·L −1 .…”

“…During stomatal closure, K + out channels are activated and potassium effluxes from guard cells result in the reduction of turgor and shrinking of volume [4,5] . Inward potassium channels regulation by La 3+ have been studied previously [6] . Here we present our studies of effects of La 3+ and Eu 3+ on K + out channels in Vicia guard cells by using whole-cell patch clamping method [7] .…”