Arnd G. Heyer

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Many temperate plant species such as Arabidopsis thaliana are able to increase their freezing tolerance when exposed to low, nonfreezing temperatures in a process called cold acclimation. This process is accompanied by complex changes in gene expression. Previous studies have investigated these changes but have mainly focused on individual or small groups(More)
Low temperature is a primary determinant of plant growth and survival. Using accessions of Arabidopsis (Arabidopsis thaliana) originating from Scandinavia to the Cape Verde Islands, we show that freezing tolerance of natural accessions correlates with habitat winter temperatures, identifying low temperature as an important selective pressure for(More)
In many plants raffinose family oligosaccharides are accumulated during cold acclimation. The contribution of raffinose accumulation to freezing tolerance is not clear. Here, we investigated whether synthesis of raffinose is an essential component for acquiring frost tolerance. We created transgenic lines of Arabidopsis thaliana accessions Columbia-0 and(More)
Numerous studies have been published that attempted to correlate fructan concentrations with freezing and drought tolerance. Studies investigating the effect of fructan on liposomes indicated that a direct interaction between membranes and fructan was possible. This new area of research began to move fructan and its association with stress beyond mere(More)
To withstand desiccation, many invertebrates such as rotifers, nematodes and tardigrades enter a state known as anhydrobiosis, which is thought to require accumulation of compatible osmolytes, such as the non-reducing disaccharide trehalose to protect against dehydration damage. The trehalose levels of eight tardigrade species comprising Heterotardigrada(More)
The role of sucrose cleavage in determining sink strength in potato was investigated by generating transgenic potato plants that expressed a yeast invertase in either the cytosol or apoplast of tubers. Cytosolic localization gave rise to a reduction in tuber size and an increase in tuber number per plant whereas apoplastic targeting led to an increase in(More)
Heterosis is broadly defined as the increased vigour of hybrids in comparison to their parents. In the model plant Arabidopsis thaliana, a significant heterosis effect on leaf-freezing tolerance was observed in the F(1) generation of a cross between the accessions Columbia-0 (Col) and C24. Parental Col plants were significantly more freezing-tolerant than(More)
We isolated an Arabidopsis thaliana mutant line carrying an insertion of the En-1 transposable element at the ADC2 locus. The insertion causes a knockout of the arginine decarboxylase 2 gene. We demonstrated that ADC2 is the gene responsible for induction of the polyamine biosynthetic pathway by osmotic stress. No induction of ADC activity by the osmolite(More)
A role of non-reducing sugars like sucrose and raffinose in the protection of plant cells against damage during freezing has been proposed for many species, but reports on physiological effects are conflicting. Non-aqueous fractionation of mesophyll cell compartments in Arabidopsis thaliana was used to show that sucrose and raffinose accumulate in plastids(More)
By screening a cDNA library of artichoke (Cynara scolymus) blossom discs for fructosyltransferases, we isolated a clone designated Cy21. The deduced amino acid sequence shows homology to acid beta-fructosyl hydrolases and to the sucrose-fructan 6-fructosyltransferase (6-SFT) of barley. Transiently expressed in Nicotiana tabacum protoplasts, the Cy21(More)