Cloning and functional characterization of a cation–chloride cotransporter gene OsCCC1

Abstract

Potassium (K+) and chloride (Cl-) are two essential elements for plant growth and development. While it is known that plants possess specific membrane transporters for transporting K+ and Cl-, it remains unclear if they actively use K+-coupled Cl- cotransporters (KCC), as used in animals, to transport K+ and Cl-. We have cloned an Oryza sativa cDNA encoding for a member of the cation-Cl- cotransporter (CCC) family. Phylogenetic analysis revealed that plant CCC proteins are highly conserved and that they have greater sequence similarity to the sub-family of animal K--Cl- cotransporters than to other cation-Cl- cotransporters. Real-time PCR revealed that the O. sativa cDNA, which was named OsCCC1, can be induced by KCl in the shoot and root and that the expression level was higher in the leaf and root tips than in any other part of the rice plant. The OsCCC1 protein was located not only in onion plasma membrane but also in O. sativa plasma membrane. The OsCCC1 gene-silenced plants grow more slowly than wild-type (WT) plants, especially under the KCl treatment regime. After 1 month of KCl treatment, the leaf tips of the gene-silenced lines were necrosed. In addition, seed germination, root length, and fresh and dry weight were distinctly lower in the gene-silenced lines than in WT plants, especially after KCl treatment. Analysis of Na+, K+, and Cl- contents of the gene-silenced lines and WT plants grown under the NaCl and KCl treatment regimes revealed that the former accumulated relatively less K+ and Cl- than the latter but that they did not differ in terms of Na+ contents, suggesting OsCCC1 may be involved in K+ and Cl- transport. Results from different tests indicated that the OsCCC1 plays a significant role in K+ and Cl- homeostasis and rice plant development.

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

“…Instead, CCC fluorescence was detected in the Golgi and TGN. This contrasts with the described localization of OsCCC, where PM localization was reported to be present in onion epidermis and rice root cells (Kong et al, 2011). Yet, in agreement with our findings, AtCCC peptides have been identified in the Golgi and TGN in four independent proteomic studies (Sadowski et al, 2008;Drakakaki et Table I).…”

“…GFP fusions of OsCCC from rice (ssp. japonica) were reported to localize to the plasma membrane (PM) of onion (Allium cepa) epidermal cells and rice root cells (Kong et al, 2011). Although these data are consistent with the proposed role for plant CCCsof net xylem loading and/or retrieval of Na + , K + , and Cl -through the PM of root stelar cells (ColmeneroFlores et al, 2007)-this hypothesis was questioned by Teakle and Tyerman (2010).…”

A Cation-Chloride Cotransporter Gene Is Required for Cell Elongation and Osmoregulation in Rice

“…Furthermore, both VviCCC and AtCCC were observed to be localized at the Golgi and trans-Golgi network (Henderson et al, 2015). On the other hand, OsCCC1 in rice was partially characterized in terms of salt stress (Kong et al, 2011). Knockdown of this gene resulted in increased sensitivity to salt stress, especially to high KCl (Kong et al, 2011).…”

“…On the other hand, OsCCC1 in rice was partially characterized in terms of salt stress (Kong et al, 2011). Knockdown of this gene resulted in increased sensitivity to salt stress, especially to high KCl (Kong et al, 2011). The concentration of K + and Cl 2 was decreased in both the roots and shoots of knockdown lines compared with the wild type, whereas that of Na + was hardly affected by suppression of this gene.…”

Identification of a Stelar-Localized Transport Protein That Facilitates Root-to-Shoot Transfer of Chloride in Arabidopsis

“…However, the molecular determinants of long-distance Cl -transport in plants and how it is regulated in response to salinity stress are still largely unknown (Teakle and Tyerman, 2010;Henderson et al, 2014). While some candidate proteins, such as cation-Cl -cotransporters in Arabidopsis (Colmenero-Flores et al, 2007) and rice (Oryza sativa; Kong et al, 2011) have been proposed to retrieve Cl -from the xylem, there are still unresolved questions in regard to their localization and mode of action (Teakle and Tyerman, 2010;Henderson et al, 2015).…”