Development of bisphenol A (BPA)-sensing indicator Arabidopsis thaliana which synthesizes anthocyanin in response to BPA in leaves

Bisphenol A (BPA) is an estrogenic endocrine disruptor which disturbs a normal animal development. We generated an indicator plant that senses and provides a clear visual indicator of an estrogen-like compound BPA in the environment. We developed transgenic Arabidopsis lines expressing a construct designed to synthesize anthocyanin (thus showing a red color) in response to BPA. We transformed Arabidopsis with a recombinant vector containing the chimeric estrogen receptor (XVE region), LAP and coding region of PtrMYB119 (transcription factor involved in anthocyanin biosynthesis in poplar and Arabidopsis). Upon binding of the estrogen compound to the ligand-binding domain of E (estrogen receptor) in XVE, the XV domain binds to LAP promoter and triggering the transcription of PtrMYB119 with a subsequent enhancement of anthocyanin biosynthetic gene expression, resulting in anthocyanin synthesis. The leaves of the transgenic Arabidopsis line XVE-PtrMYB119 turned red in the presence of 10 ppm BPA. The transcript level of PtrMYB119 peaked at day 3 of BPA exposure, then decreased to its minimal level at day 5. Similar expression patterns to that of PtrMYB119 were detected for genes encoding the anthocyanin biosynthetic enzymes chalcone synthase, chalcone flavanone isomerase, flavanone 3-hydroxylase, dihydroflavonol 4-reductase, anthocyanidin synthase, and UFGT (UGT78D2). The leaves of transgenic plants did not turn red in response to BPA at concentrations below 10 ppm, but PtrMYB119 expression was induced by BPA at concentrations as low as 1 ppt BPA. Since this transgenic plant turns red in the presence of BPA without any experimental procedures, this line can be easily used by non-scientists.