CsFEX, a Fluoride Export Protein Gene from Camellia sinensis, Alleviates Fluoride Toxicity in Transgenic Escherichia coli and Arabidopsis thaliana.

A fluoride export gene ( CsFEX) was newly found and isolated from Camellia sinensis, and its functions in detoxifying F were investigated in transgenic Escherichia coli and Arabidopsis thaliana. CsFEX contains two crcB domains, which is the typical structure in plants. The expression of CsFEX in C. sinensis is tissue-specific and related to maturity of leaves, and its expression is significantly induced by F treatments in different tissues of C. sinensis, particularly in leaves. Additionally, the growth of C. sinensis, E. coli, and A. thaliana can all be inhibited by F treatment. However, the growth of CsFEX-overexpression E. coli was increased with lower F content under F treatment compared to the control. Similarly, the germination and growth of CsFEX-overexpression A. thaliana were enhanced with lower F content under F treatment compared to the wild type. CsFEX relieves F toxicity in the transgenic E. coli and A. thaliana by alleviating F accumulation.