Overexpression of CsCLCc, a Chloride Channel Gene from Poncirus trifoliata, Enhances Salt Tolerance in Arabidopsis

Chloride channels (CLCs) have been reported to be involved in plant adaptation to salt stress by regulating Cl− homeostasis. In this study, a putative CLC-encoding gene, CsCLCc, was isolated from trifoliate orange [Poncirus trifoliata (L.) Raf]. The deduced amino acids of CsCLCc share high identity with other CLC-like sequences, which also contain domains common in CLC-like transmembrane segments and cystathionine β-synthase domains. Quantitative reverse transcription PCR analysis revealed that the CsCLCc gene expressed in the leaves and roots of trifoliate orange was upregulated by ABA, 4 °C, and NaCl. Transformation of Arabidopsis AtCLCc mutant clcc with 35S::CsCLCc improved seed germination in transgenic plants under salinity. In addition, under 200 mM NaCl treatment, the reduction in fresh weight, electrolyte leakage, and chlorophyll content was lower in the transgenic seedlings than that in mutant or wild type. This was further supported by the observation that the total Cl− accumulated in the roots and shoots was lower in transgenic plants than that in mutant or wild type. Our results indicate that CsCLCc could play an important role in Cl− homeostasis and could be an important gene target for improving salt tolerance in plants.