Plasma membrane depolarization‐activated calcium channels, stimulated by microtubule‐depolymerizing drugs in wild‐type Arabidopsis thaliana protoplasts, display constitutively large activities and a longer half‐life in ton 2 mutant cells affected in the organization of cortical microtubules

Abstract

SummaryDepolarization-activated plasma membrane calcium channels have been suggested to play prominent roles in signal perception and transduction processes during growth and development of higher plants. The existence of such channels has recently been established in higher plant cells. However, patch-clamp experiments have shown that their activity is very low and decreases very rapidly after the establishment of the whole-cell configuration, due most probably to protein-protein interactions involving microtubules. The present study takes advantage of the existence of Arabidopsis thaliana mutants referred to as ton 2 mutants reported to be affected in their microtubule organization, to address the physiological relevance of such a hypothesis based on a pharmacological approach. Patch-clamp studies showed that depolarization-activated calcium channel activities in ton 2 protoplasts were 10-fold higher and their relative half-life threetimes longer than in wild-type protoplasts. In addition, oryzalin and colchicine, which disrupt the microtubule organization, stimulated and stabilized calcium channel activities in wild-type but remained ineffective on ton 2 protoplasts. However, although the microtubules appeared important in the regulation of calcium channels

Effect of Secondary Metabolites Associated with Anaerobic Soil Conditions on Ion Fluxes and Electrophysiology in Barley Roots

“…As both of these channels are TEA 1 sensitive, inhibition of K 1 efflux by TEA 1 in our experiments (Fig. 7) (Thion et al, 1998;Miedema et al, 2001). These play a prominent role in signal perception and transduction in plants (Thion et al, 1998).…”

“…7) (Thion et al, 1998;Miedema et al, 2001). These play a prominent role in signal perception and transduction in plants (Thion et al, 1998). Regardless of the type of Ca 21 -permeable channel, increased Ca 21 uptake will provide a positive feedback to further depolarize the membrane potential, amplifying the effect of phenolics on K 1 transport (as depicted in a tentative model in Fig.…”

Calcium Signals: The Lead Currency of Plant Information Processing

“…Although the properties of DACCs and HACCs are well studied electrophysiologically (Grabov and Blatt, 1998;Thion et al, 1998;Thuleau et al, 1998;Hamilton et al, 2000;Pei et al, 2000;Klusener et al, 2002), the molecular identity of these channels is still unknown . It is assumed that DACCs contribute to the short transient influx of Ca 2+ in response to various stimuli, including chilling and microbe interaction (Thion et al, 1998). HACCs contribute to a sustained Ca 2+ influx in response to ABA (Hamilton et al, 2000;Pei et al, 2000), blue light (Harada and Shimazaki, 2009), and Ca 2+ nutrition (Miedema et al, 2001(Miedema et al, , 2008.…”

Alteration of Oriented Deposition of Cellulose Microfibrils by Mutation of a Katanin-Like Microtubule-Severing Protein

“…Several Arabidopsis mutants, such as fass (Torres-Ruiz and Jürgens, 1994;McClinton and Sung, 1997), ton1 and ton2 (Traas et al, 1995;Thion et al, 1998), cho (Mayer et al, 1999), hal (Mayer et al, 1999), pfi (Mayer et al, 1999), por (Mayer et al, 1999), fra2/bot1 (Bichet et al, 2001;Burk et al, 2001), and mor1 (Whittington et al, 2001), have been shown to alter cortical MT patterns and affect cellular morphology. The genes for two of these mutants have been cloned and characterized.…”