The secondary metabolite DIMBOA belongs to the class of benzoxazinoids and represents an important part of general plant defence in Zea mays. The DIMBOA biosynthesis genes (Bx genes) show a similar expression pattern. Their transcription might therefore be activated by the same transcription factors. A comparative analysis of the Bx promoters led to the identifi-cation of a conserved Bx sequence element. Two transcription factors belonging to class I of HD-Zip proteins could be isolated from maize for the first time. Both proteins are able to form homo- and heterodimers and function as activators of gene expression in vitro. As they show specific binding to the conserved Bx element in vitro and in vivo, both proteins are interesting candidates as transcriptional regulators of Bx gene expression.
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