Expression of multiple genes encoding bacterial enzymes for phytoremediation in transgenic tree

点击翻译按钮获取中文摘要

Phytoremediation is considered to be one of the cost-effective ways for successive degradation of chlorinated aromatic compounds such as PCB which are resistant to degradation for decades. Several bacteria are known to degrade PCB and other chlorinated aromatic compound. The cbnA gen encoding chlorocatechol dioxigenase and the cbnB gene encoding chloromuconate cycloisomerase from Ralstonia eutropha NH9, catalyze the important steps for degradation of chlorocatechols which is intermediate compounds from PCBs by many bacteria. They cleaves the aromatic ring of 3-chlorocatechol to produce toxically reduced 2-chloromuconate and muconolactone. In this study, we constructed a binary vector pCAMBIA-E7131-cbnA-cbnB transcribing cbnA and cbnB gene under the control of CaMV 35S promoter with enhancers, and introduced to Arabidopsis and hybrid poplar (Populus tremula x tremuloides) by Agrobacterium mediated transformation. Transgenic lines were isolated for subsequent analyses. PCR and Western blot analysis indicated that both genes were integrated and expressed in Arabidopsis and poplar cells. Chlorocatechol dioxigenase activity was quantitatively detected by HPLC assay in transgenic poplar cells. Transgenic Arabidopsis showed resistance to chlorocatechol and muconate. The results showed that the cbnA gene and cbnB gene were successfully expressed in poplar cells and Arabidopsis..For phytoremediation of pollutants in contaminated soil, the genes intorduced into plant cells should be expressed in root tissues since most of the contaminated chemicals are in soil. To isolate strong promoters for root specific expression, we cloned the gene encoding a phosphate transporter from Eucalyptus and Northern blot analysis indicated that its expression is root specific.