Secondary Metabolism

Plant secondary metabolism provides us with a wealth of pharmaceuticals, pigments and aroma compounds. Plant natural products (secondary metabolites) are of fundamental importance in ecology by regulating the interaction of plants with their fellow neighbors and with other organisms like beneficial and harmful microbes as well as insects and other herbivores. The research in the department focuses on investigation of regulatory mechanisms governing the biosynthesis of plant secondary compounds and on the phylogeny of the enzymes and genes involved, particularly within phenylpropanoid and isoprenoid metabolism.

Two research groups (RGs) are involved in work on plant transferases, specifically malate- and choline hydroxycinnamic acid (HCA)-transferases and various HCA glycosyltransferases from Arabidopsis and oilseed rape (RG ‘Phenylpropanoid Metabolism’) and methyltransferases from the iceplant (RG ‘Metabolite Profiling and Protein Biochemistry’). Other transferases, which accept β-acetal esters as acyl donors could be classified as serine carboxypeptidase-like (SCPL) acyltransferases. Important objectives of this work, which is carried out in collaboration with researchers from the Faculty of Biochemistry and Biotechnology at the University of Halle-Wittenberg, are the elucidation of structure-function relationships of these enzymes. In a biotechnology-oriented project on oilseed rape we have managed to strongly suppress the content of antinutritive bitter compounds in seeds thus enabling the utilization of ground seed residues as a source of high-quality protein. These investigations are being continued in a cooperation with German industrial partners and academic researchers from Canada funded by the federal agency BMBF. In this context the expertise acquired in Metabolite Profiling will be applied to GMO oilseed rape and will be connected with the analytical procedures established in the Department of Stress and Developmental Biology.

Three RGs investigate mutualistic-symbiotic interactions between plants roots and soil-borne fungi, the arbuscular mycorrhizas. These widespread symbioses can considerably improve plant nutrition. The RG ‘Cell Biology of Mycorrhiza’ focuses on the role of phytohormones (jasmonates) in this interaction and on cytological aspects of mycorrhization, particularly on changes in plastid morphology and metabolism. Another project is on analysis of effects of an altered carbohydrate status in transgenic plants on mycorrhization. A new focus is the functional analysis of signals between shoot and root in the systemic response to wounding and the role of jasmonates in adventitious root formation. The RG ‘Molecular Physiology of Mycorrhiza’ investigates the biosynthesis of various carotenoid cleavage products (apocarotenoids) in mycorrhizal roots and aims to elucidate the function of these compounds in the symbiosis by using gene silencing approaches. Additional projects in this RG are directed to an improved understanding of the organisation, differential expression and evolution of genes of the plastidial methylerythritol phophate (MEP) pathway in isoprenoid biosynthesis. Metabolite profiling of mycorrhizal roots vs. non-mycorrhizal roots and extensive data analysis by bioinformatics are areas covered by the RG ‘Metabolite Profiling and Protein Biochemistry’.