Dr. Arnd Heyer
New Position: Chair of Plant Biotechnology, Universität Stuttgart
The group is interested in the roles primary metabolites play in plant adaptations to changing environmental conditions. Work centres on oligomeric carbohydrates like fructans (oligomers of fructose) and on polyamines (a group of ubiquitous polycations). Most experiments are done in potato and the model plant Arabidopsis thaliana.
Soluble sugars play important roles in plant primary metabolism as well as in plant reactions to changing environmental conditions. Work in the "Plant-Environment Interaction" group at the MPI Golm is centered around endogenous and environmental limitations of plant productivity and the role soluble sugars play in this respect. Main topics are transport and storage of carbohydrates and plant adaptation to abiotic stresses like cold and drought.
The most important soluble sugar in plants is sucrose: it is the end product of carbon dioxide assimilation in the green leaves, in most species it is the long distance transport form of fixed energy that is distributed among the various sink organs, and in some plants, e.g. sugar beet or sugar cane, it is a storage carbohydrate. How the photosynthetic capacity to synthesize sucrose and the demand for assimilates are integrated, and how different heterotrophic organs like flowers and roots compete for delivered sucrose, is largely unknown. We are interested in enzymes that are involved in sucrose metabolism and distribution and how they contribute to the regulation of primary metabolism.
Only about 12% of the land plants contain soluble oligosaccharides based on fructose molecules, the so-called fructans. Fructans are used as short-term storage compounds in grasses, where they accumulate during periods of high light intensity or low temperature. They are transported in some Agave species. In dicotyledonous plants, they are stored for longer periods in specialized organs. The enzymes involved in fructan metabolism have emerged repeatedly in evolutionary terms. Although fructan synthesis seems to be characteristic for ecologically successful plant species, the physiological advantage of fructan storage is not yet well understood. There are also clear indications that fructans play a role in plant adaptation to environmental stresses like cold or drought, but a mechanism for a protective function remains largely unknown.
Besides plants, fructans are also synthesized by various bacteria and some fungi. Bacterial fructans usually have very high molecular weights and sometimes very interesting structures.
Plant adaptation to abiotic stress is a complex phenomenon involving different metabolic and morphological adjustments. Soluble sugars like sucrose, raffinose type oligosaccharides, and also fructans seem to play a role in the different strategies of different species. Besides carbohydrates, other compounds like, for example, polyamines have been implicated in plant stress tolerance. Polyamines are a group of polycations ubiquitous among living organisms. Despite their universal occurrence, their physiological role is not yet understood. We are interested in exploring the physiological roles of these molecules, especially in the context of stress mediation.