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Forward chemical genetic screens in Arabidopsis identify genes that influence sensitivity to the phytotoxic compound sulfamethoxazole

Karl J Schreiber3, Ryan S Austin4, Yunchen Gong2, Jianfeng Zhang2, Pauline Fung2, Pauline W Wang2, David S Guttman12 and Darrell Desveaux12*

Author Affiliations

1 Department of Cell & Systems Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada

2 Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON, M5S 3B2, Canada

3 Current address: Department of Plant & Microbial Biology, University of California, Berkeley, CA, 94720-3102, USA

4 Current address: Southern Crop Protection and Food Research Centre, Agriculture & Agri-Food Canada, London, ON, N5V 4T3, Canada

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BMC Plant Biology 2012, 12:226  doi:10.1186/1471-2229-12-226

Published: 24 November 2012


The sulfanilamide family comprises a clinically important group of antimicrobial compounds which also display bioactivity in plants. While there is evidence that sulfanilamides inhibit folate biosynthesis in both bacteria and plants, the complete network of plant responses to these compounds remains to be characterized. As such, we initiated two forward genetic screens in Arabidopsis in order to identify mutants that exhibit altered sensitivity to sulfanilamide compounds. These screens were based on the growth phenotype of seedlings germinated in the presence of the compound sulfamethoxazole (Smex).

We identified a mutant with reduced sensitivity to Smex, and subsequent mapping indicated that a gene encoding 5-oxoprolinase was responsible for this phenotype. A mutation causing enhanced sensitivity to Smex was mapped to a gene lacking any functional annotation.

The genes identified through our forward genetic screens represent novel mediators of Arabidopsis responses to sulfanilamides and suggest that these responses extend beyond the perturbation of folate biosynthesis.

Chemical genomics; Sulfanilamides; Arabidopsis thaliana