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Speakers - Alain Hehn

Type of the Presentation: (Plenary Lecture)

 

IDENTIFICATION AND CHARACTERIZATION OF THE FURANOCOUMARIN BIOSYNTHESIS: AN OVERVIEW

Alain Hehn

   Laboratory Agronomy and Environment, Université de Lorraine. France

To adapt to their environment, plants have developed a wide set of molecules that allow them to defend themselves against various kinds of aggression. Among this multitude of specialized metabolites are the furanocoumarins (FC) which represent a case of school for such arms race. The appearance and diversification of these molecules is tightly related to the adaptation of phytophagous insects to the deleterious properties of these molecules. FC are deriving from the metabolism of coumarins and have mainly been described in 4 plant families: Fabaceae, Moraceae, Apiaceae and Rutaceae. Toxicity of FC represents a major problem for the exploitation of these plants by humans. Phototoxic activities can lead to severe skin erythema. Actually these properties have been used to treat some skin diseases such as psoriasis and vitiligo. These molecules have also been described as cytochromes P450 inhibitors, enzymes involved in the degradation of molecules in human liver. They have thus been described as being responsible for the so called grapefruit effect.

Work carried out in the 1990s based on biochemical approaches allowed the identification of the intermediates as well as the enzymatic reactions of this biosynthesis pathway. The first genes involved in the synthesis of these molecules have been identified a decade ago. Studies carried out since then make it possible to better understand how this biosynthetic pathway appeared in Apiaceae. The identification of genes belonging to the cytochrome P450 family, to the dioxygenase alpha keto-glutarate dependent family, and more recently to the enzymes of the prenyltransferase family makes it possible to understand the various steps of this biosynthesis pathway at the molecular level.

These new data open new outlooks at a fundamental but also applied point of view. Indeed, the acquired knowledge gives new elements on the evolution of biosynthetic pathways of specialized metabolism in plants. They also make it possible to imagine strategies for regulating the synthesis of these molecules using biotechnological tools.