Potassium channels in barley: cloning, functional characterization and expression analyses in relation to leaf growth and development

Abstract

It is not known how the uptake and retention of the key osmolyte K + in cells are mediated in growing leaf tissue. In the present study on the growing leaf 3 of barley, we have cloned the full-length coding sequence of three genes which encode putative K + channels (HvAKT1, HvAKT2, HvKCO1/HvTPK1), and of one gene which encodes a putative K + transporter (HvHAK4). The functionality of the gene products of HvAKT1 and HvAKT2 was tested through expression in Xenopus laevis oocytes. Both are inward-rectifying K + channels which are inhibited by Cs

The Os-AKT1 Channel Is Critical for K+ Uptake in Rice Roots and Is Modulated by the Rice CBL1-CIPK23 Complex

“…Similar regulatory mechanisms involving CBL-CIPK complexes modulating K + channel were reported for several different plant species based on electrophysiological analyses. Two AKT1-like channels, Hv-AKT1 from barley and Vv-K1.1 from grapevine both could be activated by Arabidopsis CBL1 and CIPK23 in X. laevis oocytes (Boscari et al, 2009;Cuéllar et al, 2010). Furthermore, another K + channel from grapevine, Vv-K1.2, was characterized as a voltage-gated inward K + channel.…”

“…Several AKT1 orthologs have been identified in other plant species, such as Os-AKT1 in rice (Oryza sativa; Fuchs et al, 2005), Zm-ZMK1 in maize (Zea mays; Philippar et al, 1999), Ta-AKT1 in wheat (Triticum aestivum; Buschmann et al, 2000), Hv-AKT1 in barley (Hordeum vulgare; Boscari et al, 2009), Sl-LKT1 in tomato (Solanum lycopersicum; Hartje et al, 2000), and St-SKT1 in potato (Solanum tuberosum; Zimmermann et al, 1998). Similar regulatory mechanisms, with CBL-CIPK complex-modulating K + channels, were also reported in barley (Boscari et al, 2009) and grape (Vitis vinifera) plants (Cuéllar et al, 2010(Cuéllar et al, , 2013.…”

Potassium (K + ) gradients serve as a mobile energy source in plant vascular tissues

“…Although intrinsically a K in channel, it was shown in heterologous expression systems that AKT2 can be converted by phosphorylation into a nonrectifying channel mediating both K + uptake and release (2)(3)(4). Interestingly, AKT2-like channels are found only in higher plants (5)(6)(7)(8)(9)(10)(11)(12)(13) (Fig. S1).…”

Apoplast Acidification in Growing Barley (Hordeum vulgare L.) Leaves

“…Taking into consideration all of the present results (expression analysis and physiological measurements with pH, H + transport activity and K + uptake during the leaf development) and published information about expression of HvHAK4 (Rubio et al, 2000;Boscari et al, 2009) From the copy number of PCR reaction the total copy number in 1 µg RNA could easily be calculated through multiplying the results with respective dilution factors; these were typically 4,000 using 250 pg template in each reaction: Example for these calculations can be found on Table 7.1 for Golf and Table 7.2 for Jersey barley cultivar. Water ________________________________________________________________ -4 -1.1.2 pH conditions in the apoplast ________________________________________________ -4 -1.1.3 'Acid growth' theory ________________________________________________________ -5 -1.1.3.1 'Acid growth' and effect of auxin and fusiccoccin on growth _____________________ -5 -1.1.3.2…”