The Key Role of Chlorocatechol 1,2-Dioxygenase in Phytoremoval and Degradation of Catechol by Transgenic Arabidopsis

Abstract

Transgenic exploitation of bacterial degradative genes in plants has been considered a favorable strategy for degrading organic pollutants in the environment. The aromatic ring characteristic of these pollutants is mainly responsible for their recalcitrance to degradation. In this study, a Plesiomonas-derived chlorocatechol 1,2-dioxygenase (TfdC) gene (tfdC), capable of cleaving the aromatic ring, was introduced into Arabidopsis (Arabidopsis thaliana). Morphology and growth of transgenic plants are indistinguishable from those of wild-type plants. In contrast, they show significantly enhanced tolerances to catechol. Transgenic plants also exhibit strikingly higher capabilities of removing catechol from their media and high efficiencies of converting catechol to cis,cis-muconic acid. As far-less-than-calculated amounts of cis,cis-muconic acid were accumulated within the transgenic plants, existence of endogenous TfdD-and TfdE-like activities was postulated and, subsequently, putative orthologs of bacterial tfdD and tfdE were detected in Arabidopsis. However, no TfdC activity and no putative orthologs of either tfdC or tfdF were identified. This work indicates that the TfdC activity, conferred by tfdC in transgenic Arabidopsis, is a key requirement for phytoremoval and degradation of catechol, and also suggests that microbial degradative genes may be transgenically exploited in plants for bioremediation of aromatic pollutants in the environment.

Selective Detoxification of Phenols by Pichia pastoris and Arabidopsis thaliana Heterologously Expressing the PtUGT72B1 from Populus trichocarpa

“…Among the seven phenols tested, PtUGT72B1 from P. trichocarpa was confirmed to catalyze the O -glucosylation of phenol, hydroquinone, and catechol when expressed in A. thaliana and P. pastoris . Phenol, hydroquinone, and catechol [32] have significant toxicities to A. thaliana . Plants transform xenobiotics via a three-phase detoxification system: conversion, conjugation, and compartmentalization [33].…”

Prospects for using combined engineered bacterial enzymes and plant systems to rhizoremediate polychlorinated biphenyls

“…Although the toxicity of 2,3‐dihydroxy‐chlorobiphenyls to plants has never been examined directly, Camara and colleagues () have shown they are toxic to bacterial cells, Novakova and colleagues () have shown they are toxic to tobacco plants and Lovecka and colleagues () have shown that monohydroxylated PCB metabolites are toxic to plants depending on number and position of the chlorine atoms. Furthermore, the toxicity of catechol to plants has been clearly demonstrated by Liao and colleagues (). These are among the many observations supporting the use of transgenic plants producing 2,3‐DHBD for rhizoremediation of PCB‐contaminated sites since these plants are likely to be more resistant to the PCB metabolites produced by plants and their associated rhizobacteria than the non‐transgenic parents.…”

Phylloremediation of Air Pollutants: Exploiting the Potential of Plant Leaves and Leaf-Associated Microbes

“…Co-expression of HPS and PHI in tobacco plants resulted in 20% reduction of formaldehyde compared to the control plants (Chen et al, 2010 ). In another study, a chlorocatechol 1,2-dioxygenase gene ( tfdC ) derived from the bacteria Plesiomonas was introduced into Arabidopsis thaliana (Liao et al, 2006 ). Transgenic plants showed enhanced tolerances to catechol, an aromatic ring.…”