Homoglutathione confers tolerance to acifluorfen in transgenic tobacco plants expressing soybean homoglutathione synthetase.

Homoglutathione (hGSH), which is present in some leguminous plants, is preferred over GSH in in vitro conjugation of acifluorfen and fomesafen by glutathione S-transferase. To investigate the function of hGSH in in vivo detoxification of xenobiotics, we evaluated herbicide tolerance of transgenic tobacco plants expressing soybean homoglutathione synthetase in the cytosol or chloroplasts. Transgenic plants synthesizing hGSH in the cytosol were more tolerant to acifluorfen than wild-type plants, whereas enhanced tolerance to fomesafen was not observed. Transgenic plants synthesizing hGSH in the chloroplasts showed no enhanced tolerance to acifluorfen or fomesafen.