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I'm investigating enzymes involved in biosynthesis of benzoxazinoids (BXDs). BXDs are plant defense compounds which are found mainly in the plants of the grass family, such as wheat and maize. The pathway starts from indole-3-glycerol phosphate and leads to 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc), the predominant compound, and the related DIBOA-Glc. Among these, maize also produces other BXDs. However, the biosynthetic sequences leading to this complex mixture of products are currently not known.

In our attempt to investigate the enzymes responsible for BXD formation in maize, we have started to identify the O-methyltransferase (OMT) which converts DIMBOA-Glc to HDMBOA-Glc, thought to be more toxic than other BXDs. Recently it was shown that this conversion is strongly upregulated after herbivore feeding. Hence, a detailed understanding of this defense mechanism could speed up the breeding of herbivore-resistant maize lines.

Beside the formation of BXDs in maize, we are also interested in the activation of these important defense compounds. Activation is based on the formation of highly reactive aglucones from the plant glucoside, which occurs after tissue damage through the action of specific β-glucosidases. Two β-glucosidases, Glu1 and Glu2, were already described to be involved in BXD activation. While their biochemical properties were extensively studied in the past, their regulation is poorly understood.
last updated on 2014-04-23