Expression of nanobodies in <i>Arabidopsis thaliana</i> strengthens the absorption capacity of triclosan from growth media

Triclosan (TCS) is a broad-spectrum antimicrobial disinfectant widely used in pharmaceuticals and personal care products (PPCPs). Due to the extensive usage of PPCPs, TCS inevitably entered the environment and pose harmful effects on the ecosystem. Phytoremediation is an attractive approach to remove TCS from the environment. In this study, a gene encoding the anti-TCS nanobody was transformed into Arabidopsis thaliana (A. thaliana) to enhance the absorption capacity of TCS. Nanobodies are small antibody fragments (ca. 15 kDa) derived from the variable domain of camelid heavy-chain-only antibodies. We constructed two transgenic lines, the T-S-C line with nanobody expression throughout the plant and the T-S-P line with nanobody expression dominant in the roots, were constructed. The expression of nanobodies in A. thaliana alleviated the phytotoxicity of TCS. T-S-C and T-S-P exhibited significantly stronger tolerance to TCS toxicity than the wild type (WT), in either a solid medium system or a hydroponics system. Under the stress of TCS, the seedlings of both transgenic plants exhibited an increase in root length and fresh weight compared to those of WT. Moreover, in the presence of TCS, the activities of superoxide dismutase, peroxidase, catalase, and glutathione in transgenic plants were higher than those in WT. The concentration of TCS absorbed into the T-S-C and T-S-P plants from the solid medium increased by 50.0% and 24.1%, and from the hydroponics system increased by 55.6% and 38.0%, respectively, compared to those absorbed by WT. This study provides a proof of principle that transforming nanobodies into plants represents a novel technology to improve the efficiency of phytoremediation for environmental pollutants.