Effects of biosurfactants on assays of PCB congeners in transgenic arabidopsis plants carrying a recombinant guinea pig AhR-mediated GUS reporter gene expression system

Abstract

The transgenic Arabidopsis plants carrying a recombinant guinea pig (g) aryl hydrocarbon receptor (AhR)-mediated β-glucuronidase (GUS) reporter gene expression system were generated for assays of polychlorinated biphenyl (PCB) congeners. The selected transgenic Arabidopsis plant XgD2V11-6 exhibited a correlation between uptake of PCB126 and PCB126-induced GUS activity. Also, the plants showed induced GUS activity towards the supplemental indole 3-acetic acid (IAA). Thus, the GUS assay may reflect induction by both endogenous and exogenous AhR ligands. When biosurfactants, MEL-B, produced in the culture of yeast isolated from plants were used for assays of PCB congeners in the transgenic Arabidopsis plants, they showed marked PCB126 dose-dependent and toxic equivalency factor (TEF) dependent GUS activities. The effects of biosurfactants were clearer when the plants were cultivated on soils containing PCB congeners for 7 days as compared with on soils for 3 days as well as in the medium for 3 days. Threfore, it was estimated that biosurfactants form micellae with PCB congeners, which are easily uptaken by the plants in a mode of passive diffusion, transport into the aerial parts and then induce GUS activity.

Keywords:

• aryl hydrocarbon receptor (AhR)
• polychlorinated biphenyl (PCB)
• biosurfactant
• Arabidopsis

Acknowledgments

This work was supported by the Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (c) KAKENHI 21510095 and 17208029, and 2004 “High-Tech Research Center” Project for Private Universities: matching fund subsidy from MEXT (Ministry of Education, Culture, Sports, Science and Technology).