Cloning and molecular analyses of the Arabidopsis thaliana chloride channel gene family

The Arabidopsis chloride channels (CLC) family includes seven members, AtCLCa–g, that can be divided into two distinct subclasses. Here we show the developmental and tissue-specific expression of Arabidopsis CLC (AtCLC) gene family, and the subcellular localization of individual members. Reverse transcription PCR (RT-PCR) analyses indicated that the family members were ubiquitously but differentially expressed in Arabidopsis. Promoter-driven β-glucuronidase (GUS) expression in transgenic Arabidopsis plants further demonstrated the overlapping but distinct expression pattern of this family, and all the family members were predominantly expressed in vascular tissues, as well as a preferential expression of AtCLCc in guard cells. When expressed as yellow fluorescent protein (YFP)-tagged fusion proteins in tobacco mesophyll protoplasts, AtCLCe was specifically localized to chloroplast; AtCLCa–c and g were localized to the vacuole membranes, whereas AtCLCd and AtCLCf were targeted to Golgi apparatus. Among the seven AtCLC members, only AtCLCc and AtCLCd could suppress, with discrepant efficacy, the cation-sensitive phenotype of Δgef1, a yeast mutant lacking the single chloride channel GEF1.