Identification and functional characterization of cation–chloride cotransporters in plants

Abstract

SummaryChloride (Cl ) ) is an essential nutrient and one of the most abundant inorganic anions in plant tissues. We have cloned an Arabidopsis thaliana cDNA encoding for a member of the cation-Cl ) cotransporter (CCC) family. Deduced plant CCC proteins are highly conserved, and phylogenetic analyses revealed their relationships to the sub-family of animal K + :Cl ) cotransporters. In Xenopus laevis oocytes, the A. thaliana CCC protein (At CCC) catalysed the co-ordinated symport of K + , Na + and Cl ) , and this transport activity was inhibited by the 'loop' diuretic bumetanide, a specific inhibitor of vertebrate Na + :K + :Cl ) cotransporters, indicating that At CCC encodes for a bona fide Na + :K + :Cl ) cotransporter. Analysis of At CCC promoter-b-glucuronidase transgenic Arabidopsis plants revealed preferential expression in the root and shoot vasculature at the xylem/symplast boundary, root tips, trichomes, leaf hydathodes, leaf stipules and anthers. Plants homozygous for two independent T-DNA insertions in the CCC gene exhibited shorter organs such as inflorescence stems, roots, leaves and siliques. The elongation zone of the inflorescence stem of ccc plants often necrosed during bolt emergence, while seed production was strongly impaired. In addition, ccc plants exhibited defective Cl ) homeostasis under high salinity, as they accumulated higher and lower Cl ) amounts in shoots and roots, respectively, than the treated wild type, suggesting At CCC involvement in long-distance Cl ) transport. Compelling evidence is provided on the occurrence of cation-chloride cotransporters in the plant kingdom and their significant role in major plant developmental processes and Cl ) homeostasis.

Grapevine and Arabidopsis cation-chloride cotransporters localise to the Golgi and trans-Golgi network and indirectly influence long-distance ion homeostasis and plant salt tolerance

“…The first plant CCC identified was auxin-independent growth protein1 (AXI1) from Nicotiana tabacum, which was originally thought to trigger auxin-independent growth of protoplasts (Harling et al, 1997), but these findings were not reproducible (Schell et al, 1999 (Colmenero-Flores et al, 2007). GFP fusions of OsCCC from rice (ssp.…”

“…VviCCC and AtCCC Localize to the Golgi and Trans-Golgi Network Although AtCCC has been functionally characterized as a membrane transporter (Colmenero-Flores et al, 2007), its subcellular localization has not been shown previously. We therefore aimed to ascertain the subcellular localizations of both AtCCC and VviCCC in planta.…”

“…Cation-chloride cotransporters (CCCs) have been proposed to be prime candidates for directly regulating ion concentration in the root xylem (Colmenero-Flores et al, 2007;Flowers and Colmer, 2008;Brumós et al, 2009;Barbier-Brygoo et al, 2011;Shabala, 2013;Wegner, 2014;Fricke, 2015). CCCs from mammals and fish have been relatively well characterized; they transport the cations K + and/or Na + with the anion Cl -in a 1:1 ratio, and hence, facilitate electroneutral transport (Gamba, 2005).…”

Salt-induced respiration in Bruguiera cylindrica — role in salt transport and protection against oxidative damage

“…It has been reported that Cl -influx into plants under salt stress occurs passively through anion channels and usually accompanies transport of the corresponding cation (Lorenzen et al, 2004). More recently the presence of cation-Cl -cotransporters, which play an important role in maintaining ion homeostasis in animals, has been reported in plants (Colmenero-Flores et al, 2007). Hence the transport of Cl -and cations like Na + and K + appear to be interdependent.…”

Arabidopsis CALCINEURIN B-LIKE10 Functions Independently of the SOS Pathway during Reproductive Development in Saline Conditions

“…Mutations in the NHX1 and NHX2 transporters led to reductions in filament elongation and anther dehiscence as well as to sterile pistils (Bassil et al, 2011). When the Arabidopsis CCC protein was mutated, flowers were sterile (Colmenero-Flores et al, 2007). The NHX and CCC genes appear to regulate ion homeostasis when plants are grown in control conditions, while CBL10 appears to prevent a disruption in ion homeostasis when plants are grown in the presence of salt (Fig.…”