Selection of plants for roles in phytoremediation: the importance of glucosylation

摘要

Over?￠????expression and transposon mutagenesis in root cultures of Arabidopsis thaliana demonstrated the importance of the family 1 glycosyltransferase UGT72B1 in catalysing the N ?￠????glucosylation of the persistent pollutant 3,4?￠????dichloroaniline (DCA). In phytotoxicity studies with DCA in seedlings, over?￠????expression of UGT72B1 enhanced sensitivity, whereas the knockouts were more resistant than the controls. In contrast, manipulating the expression of UGT72B1 had no effect on the O ?￠????glucosylation, or toxicity, of chlorophenols. When N ?￠????glucosylation was disrupted in plants, radioactivity derived from [ 14 C]?￠????DCA became covalently bound into high molecular weight insoluble material, principally associated with the lignin fraction. This suggested that insolubilization into stable cell wall components represented a more effective mechanism of DCA detoxification than the formation of N ?￠????glycosidic conjugates. A screen of plants used in remediation, identified low levels of N ?￠????glucosyltransferase activity in switchgrass and high activities in reed canary grass. When incubated with [ 14 C]?￠????DCA, reed canary grass plants accumulated soluble N ?￠????glycosides of DCA, whereas switchgrass formed insoluble residues. Consistent with the results obtained in studies with Arabidopsis , phytotoxicity trials with DCA demonstrated that switchgrass was more tolerant than reed canary grass. Our studies provide a new biochemical basis for selecting plants for useful remediating traits towards specific classes of pollutants.