Plant cell biodegradation of a xenobiotic nitrate ester, nitroglycerin

The ability of plants to metabolize the xenobiotic nitrate ester, glycerol trinitrate (GTN, nitroglycerin), was examined using cultured plant cells and plant cell extracts. Intact cells rapidly degrade GTN with the initial formation of glycerol dinitrate (GDN) and the later formation of glycerol mononitrate (GMN). A material balance analysis of these intermediates indicates little, if any, formation of reduced, conjugated or cell-bound carbonaceous metabolites. Cell extracts were shown to be capable of degrading GTN with the simultaneous formation of GDN in stoichiometric amounts. The intermediates observed, and the timing of their appearance, are consistent with a sequential denitration pathway that has been reported for the microbial degradation of nitrate esters. The degradative activities of plant cells are only tenfold less than those reported for bacterial GTN degradation. These results suggest that plants may serve a direct degradative function for the phytoremediation of sites contaminated by organic nitrate esters.