Phytoremediation of highly water-soluble and volatile organic xenobiotics often is limited because plants, and their rhizospheres, do not degrade them sufficiently. This can result in phytotoxicity, and/or volatilization of the compounds through the leaves, causing new environmental problems. Researcher of Limburgs Universitair Centrum and Brookhaven National Laboratory demonstrated that endophytic bacteria equipped with the appropriate degradation pathway improve the in planta degradation of the model compound toluene. The pTOM toluene-degradation plasmid of Burkholderia cepacia G4 was introduced by conjugation into B. cepacia L.S.2.4, a natural endophyte of yellow lupine. After successfully inoculating surface-sterilized lupine seeds with the recombinant strain, the engineered endophytic bacteria strongly degraded toluene, resulting in a marked decrease in its phytotoxicity, and a 3-4 times reduction of its evapotranspiration through the leaves. This strategy promises to greatly improve the efficiency of phytoremediating volatile organic contaminants, and to promote the acceptance of phytoremediation by regulatory agencies and the public. In this project, a similar system will be developed and tested for TCE.