The synergistic relationships between plants and their rhizospheric microbes can be used to develop a combinational bioremediation method， overcoming the constraints of individual phytoremediation or bioaugmentation method. Here， we provide a combinational transgenic plant-microbial remediation system for a more efficient removal of phenylurea herbicides (PHs) from contaminated-sites. The transgenic synthesizing the bacterial -demethylase PdmAB in the chloroplast was developed. The constructed transgenic exhibited significant tolerance to isoproturon (IPU)， a typical PH， and it took up the IPU through roots and transported to leaves， where the majority of the IPU was demethylated to 3-(4-isopropylph... More
The synergistic relationships between plants and their rhizospheric microbes can be used to develop a combinational bioremediation method， overcoming the constraints of individual phytoremediation or bioaugmentation method. Here， we provide a combinational transgenic plant-microbial remediation system for a more efficient removal of phenylurea herbicides (PHs) from contaminated-sites. The transgenic synthesizing the bacterial -demethylase PdmAB in the chloroplast was developed. The constructed transgenic exhibited significant tolerance to isoproturon (IPU)， a typical PH， and it took up the IPU through roots and transported to leaves， where the majority of the IPU was demethylated to 3-(4-isopropylphenyl)-1-methylurea (MDIPU). The produced intermediate was released outside of roots and further metabolized by the combinationally inoculated MDIPU-mineralizing bacterium sp. strain 1017-1 in the rhizosphere， resulting in an enhanced and complete removal of IPU from soil. Mutual benefits were built for both transgenic and strain 1017-1. The transgenic offered strain 1017-1 a suitable accommodation and in return， the latter protected the plant from the phytotoxicity of MDIPU. The biomass of the transgenic and the residence of the inoculated degrading microbes in the combinational treatment increased significantly compared to that in their respective individual transgenic plant treatment or bioaugmentation treatment. The influence of the structure of bacterial community by combinational treatment was between that of the two individual treatments. Overall， the combination of two approaches， phytoremediation by transgenic plants and bioaugmentation with intermediate-mineralizing microbes in the rhizosphere， represents an innovative strategy for the enhanced and complete remediation of pollutant-contaminated sites. Phytoremediation of organic pollutant-contaminated sites using transgenic plants expressing bacterial enzyme has been well described. The major constraint of transgenic plants transferred with a single catabolic gene is that they can also accumulate/release intermediates， still causing phytotoxicity or additional environmental problems. On the other hand， bioaugmentation with degrading strains also has its drawbacks including instability of the inoculated strains and low bioavailability of pollutants. In this study， the synergistic relationship between transgenic expressing the bacterial -demethylase PdmAB in the chloroplast and the inoculated intermediate-mineralizing bacterium sp. strain 1017-1 in the rhizosphere is used to develop an intriguing bioremediation method. The combinational transgenic plant-microbe remediation system shows a more efficient and complete removal of phenylurea herbicides from contaminated-sites， and can overcome the constraints of individual phytoremediation or bioaugmentation methods.
