Identification of candidate genes involved in responses of Arabidopsis to polychlorinated biphenyls based on microarray analysis

Abstract

Polychlorinated biphenyls (PCBs) are considered as persistent organic pollutants. Their long term accumulation in soils and progressive bioaccumulation in the food chain makes PCBs a risk for human health. Phytoremediation, or the use of plants to enhance pollutant dissipation, is an efficient technique for the removal of organic compounds, including PCBs. However, the molecular basis of plant responses to PCBs has not been clearly elucidated. Here we studied the effects on growth and the transcriptional profile of Arabidopsis thaliana after exposure to 2,2 0 ,3,3 0 -tetrachlorobiphenyl, a representative PCB. A comprehensive survey of global gene expression response to this PCB was done by using Arabidopsis (V4) gene expression microarray (4 9 44 K) to quantify the spatio-temporal variations in transcript abundance of 42,000 genes. The results revealed a coordinated induction or suppression of 146 or 148 genes, respectively. Of these, expression of 40 genes was validated by RT-PCR analysis.The functional classification of these PCB-responsive genes indicated their involvement in various metabolic pathways, such as ion transport, signal transduction, transcriptional regulation, and other processes related to growth and development.

Effects of Polychlorinated Biphenyls (PCBs) and Their Hydroxylated Metabolites (OH-PCBs) on Arabidopsis thaliana

“…44 A prior study focusing on the transcriptomic response of Arabidopsis exposed to 2,2′,3,3′-TeCB similarly reported overexpression of genes potentially involved in the three phases of the green liver model, including cytochrome P-450 monooxygenases, UDP-glucuronosyltransferases, and transporter proteins. 24 Based on the observations above, we hypothesize that the differentiated induction of detoxification enzymes in response to the parent PCB, 2,5-DCB, explains its lower toxicity as compared to its OH stmetabolite, 4′-OH-2,5-DCB.…”

“…However, several studies have shown more severe effects of PCBs on plants at concentrations well below the maximum concentration (100 mg L −1 ) used in our study. Jin et al 24 exposed Arabidopsis plants, growing on agar plates and in soil, to increasing concentration of 2,2′,3,3′-TeCB and observed that low concentrations (below 10 mg L −1 ) resulted in growth stimulation (e.g., increase of root length and plant height), while higher concentrations (40 to 100 mg L −1 ) resulted in growth inhibition. Wang et al 25 recently showed that exposure of alfalfa seedlings to a low concentration of 3,3′,4,4′-TeCB (3 mg L −1 ) had a significant impact on plant growth (reduction of root and shoot biomass dry weight by 17.6 and 20.6%, respectively).…”

“…Hormesis has been described in plants as well as in other organisms exposed to various types of stressors, including toxic chemicals. 21,24,28 It is believed that a low level of stress triggered cellular signaling pathways and defense mechanisms involving transcription factors, protective proteins, and antioxidant molecules, which have beneficial effects for the organisms. 29 …”

Unraveling the early molecular and physiological mechanisms involved in response to phenanthrene exposure

“…We then compared our sets of DEGs to other transcriptome analyses performed to study the effect of various xenobiotics, such as aluminum [ 37 ], atrazine [ 38 ], benzoxazolin-2(3H)-one [ 39 ], cadmium [ 40 ], polychlorinated biphenyl [ 41 ], phenol [ 42 ] selenium [ 43 ] and trinitrotoluene [ 44 ]. Overall, 77.7 % (363/467) of DEGs were shared between the xenobiotic transcriptome datasets.…”

Transcriptomic analysis of maize mature embryos from an elite maize hybrid Zhengdan958 and its parental lines

“…Although these technologies can provide rich information on gene expression models (Jin et al 2011), they are more challenging when dealing with larger inventories of genes in species and more complex genomes. For example, the genes represented by unspecific probe sets and with low expression levels cannot be reliably detected in microarrays.…”