Transport of Cl^–across the Plasma Membrane during Pollen Grain Germination in Tobacco

Abstract

The role of Cl- transport across the plasma membrane was studied in an early step of pollen grain germination in tobacco Nicotiana tabacum L. The Cl- channel blockers, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and niflumic acid, completely suppress the germination with IC(50) approximately 8 micro M. At this concentration NPPB reduces the rate of Cl- efflux out of pollen grain by 1.8-fold in the interval 5-12 min, and niflumic acid reduces the rate 1.2-fold. 4,4;-Diisothiocyanatostilbene-2,2;-disulfonic acid, a known inhibitor of Cl- channels and antiporters, completely suppresses germination as well (IC(50) = 240 micro M), but has no effect on the rate of Cl- efflux. Inhibitors of chloride co-transporters, such as furosemide, bumetanide, and bis(1,3-dibutylbarbituric acid)pentamethine oxonol, suppress the germination by less than 50%. This set of data suggests that NPPB-sensitive anion channels are involved in the activation of pollen grains in the early stage of germination.

Pollen Tube Growth Regulation by Free Anions Depends on the Interaction between the Anion Channel SLAH3 and Calcium-Dependent Protein Kinases CPK2 and CPK20

“…A negligible role for chloride in the polar growth process was claimed by early studies, using an allegedly anion-free pollen tube growth medium (Weisenseel and Jaffe, 1977). However, after rehydration and during germination, a prominent release of anions into the growth medium can be detected within minutes and provides an anion containing microenvironment (Zonia et al 2002;Matveyeva et al, 2003). Extracellular flux measurements on the basis of ion-selective electrodes with the vibrating probe technique could identify a close anion flux circuit at the pollen tube apex, which was essential for growth.…”

“…Numerous studies have demonstrated that variations of extracellular ion concentrations of both anionic and cationic nature can profoundly alter pollen tube growth characteristics and germination rate (Weisenseel et al, 1975;Holdaway-Clarke et al, 1997;Fan et al, 2001;Matveyeva et al, 2003). Hence, much attention has been drawn to the role of cations, namely H + , Ca 2+ , and K + , in pollen tube growth.…”

Mechanistic studies of perfluorooctane sulfonate, perfluorooctanoic acid uptake by maize (Zea mays L. cv. TY2)

“…1 μmolL −1 AgNO 3 or 1 mmolL −1 glycerol was used as aquaporin inhibitors (Kong et al 2007). 10 μmolL −1 anthracene-9-carboxylic acid (9-AC, Aladdin Chemistry, Co. Ltd, China), or 5 μmolL −1 4,4′-diisothiocyanostibene-2,2′-disulfonate (DIDS, Tokyo Chemical Industry, Co. Ltd, Japan), or 5 μmolL −1 5-nitro 2-(3-phenylpropylamine) benzoic acid (NPPB, Tokyo Chemical Industry, Co. Ltd, Japan) was used as anion channel inhibitors (You et al 2010;Matveyeva et al 2003). Maize seedlings were transferred to 400 mL nutrient solution containing 1.0 mgL −1 PFOS or PFOA with metabolic or aquaporin or anion-channel inhibitors.…”

Transmembrane transport of K+ and Cl− during pollen grain activation in vivo and in vitro

“…ТЕА Сl (tetraethylammonium chloride, 10 and 20 mM) and Ba(NO 3 ) 2 (5 mM) were used as potas sium channel inhibitors; anion channels were blocked with NPPB (5 nitro 2 (3 phenylpropylamino)ben zoic acid) at a concentration of 40 μM, which is suffi cient for complete suppression of tobacco pollen ger mination (Matveyeva et al, 2003).…”

“…The most studied on this matter are Са 2+ and H + , less studied is К + , and Сl -has hardly been studied (Hepler et al, 2006;Hepler and Winship, 2010). Along with this, inhibitory analy sis has shown that the activation of potassium and chloride plasmalemma channels is necessary for pol len germination in vitro (Matveyeva et al, 2003;Sze et al, 2006;Breygina et al, 2009a;Fan et al, 2001, Griessner andObermeyer, 2003).…”