PMEI-related inhibitor proteins: Their roles in the regulation of sugar and pectin metabolism

Sucrose-hydrolyzing invertases in the cell wall and the vacuole, and cell wall-localized pectin methylesterases are post-translationally regulated by inhibitory proteins belonging to the same protein family: pectin methylesterase inhibitor-related proteins (PMEI-RP). PMEI-RPs are predicted to serve multiple functions in sugar and cell wall metabolism during plant development and in response to stress exposure. This project aims at unraveling the roles of different PMEI-RPs in different plant species, plant organs and cell types. Furthermore, the biotechnological potential of up- or down-regulation of certain PMEI-RP isoforms in selected crop species is explored.
 

Inulin metabolism in Chicory

Inulin is used as carbohydrate storage compound in plants but may also be involved in several stress responses. The economically most important source is chicory, which accumulates inulin in its taproots. Biotechnological goals are to increase inulin yield and its degree of polymerization (DP). Enzymes responsible for inulin biosynthesis in chicory are sucrose:sucrose 1-fructosyltransferase (1-SST) and fructan:fructan 1-fructosyltransferase (1-FFT), inulin degradation is catalyzed by fructan 1-exohydrolases (1-FEHs). We are investigating the possibility of post-translational control of FAZYs via proteinaceous inhibitors, as found for acid invertases, enzymes evolutionarily and structurally related to FAZYs. We are pursuing 3 different strategies in order to isolate FAZY specific inhibitors: a) affinity chromatography with recombinant FAZY proteins as bait; b) Deep Sequencing of chicory cDNAs; c) Invertase inhibitor engineering.

Additionally, we have established the chicory hairy root culture (CiHRC) as a model system to explore regulatory mechanisms impacting on inulin metabolism in planta. We are currently studying aspects of hormonal regulation of FAZYs in CiHRC.
 

Regulation of Stilbene Synthesis in Vitis vinifera and the influence of Flavonoid modification on its function

Stilbenes are a small family of plant secondary metabolites and like flavonoids derived from the phenylpropanoid pathway.

The synthesis of these phenolic componds is catalysed by the initial enzymes stilbene synthase (STS) and chalcone synthase (CHS) by using the same substrates.

The increasing knowledge about the biological function and the health-promoting effects of fruit-derived flavonoids and stilbenes leds to an enhanced interest in the elucidation of biosynthetic pathways involved in their biosynthesis and modification. Recently, transcription factors controlling different pathway branches of the flavonoid pathway have been elucidated but a factor controlling stilbene biosynthesis has not been identified yet. Furthermore, the vast majority of the genes responsible for flavonoid and stilbene diversity, which has been shown to influence bioavailability, antioxidant capacity and stability of the resulting polyphenol, are yet completely unknown. Therefore we are interested in the identification and characterisation of the regulators of STS synthesis and genes encoding enzymes modifying flavonoids and stilbenes.
 

Control of lignin biosynthesis in Miscanthus

The giant grass Miscanthus spec. is one of the plant species in use for bioeconomy-directed production of organic polymers (cellulose/lignin). We study the complexity of transcriptionally controlled lignin biosynthesis as an interdisciplinary bioeconomy-targeted approach. In particular, the functionality of involved transcription factors and target promoters are explored. Furthermore, the impact of genotype and environmental cues on the kinetics of lignin biosynthesis are investigated.

 

 

Coordinator of the bioeconomy graduate program BBW ForWerts.
If there is not currently an open application round, please send your application documents to bbwforwerts@cos.uni-heidelberg.de

Director of the Marsilius Kolleg