Abstract
Four species of flowering plants comprising Arctic populations of Cerastium alpinum and Poa arctica var. vivipara and indigenous Antarctic species Colobanthus quitensis and Deschampsia antarctica were investigated. Plants derived from natural origins were grown in an experimental greenhouse in Poland (53°47′N and 20°30′E latitude). Plants for experiment were collected during spring of 2010. Soluble carbohydrates in the intact shoots of C. alpinum and C. quitensis, polar plants of the family Caryophyllaceae, and D. antarctica and P. arctica var. vivipara, representatives of the family Poaceae, were analyzed by gas chromatography, and their involvement in the plants’ response to chilling stress was examined. Plant tissues of the examined families growing in a greenhouse conditions (18–20 °C, short day 10/14 h light/darkness) differed in the content and composition of soluble carbohydrates. In addition to common monosaccharides, myo-inositol and sucrose, Caryophyllaceae plants contained raffinose family oligosaccharides (RFOs), d-pinitol and mono-galactosyl pinitols. RFOs and d-pinitol were not detected in plants of the family Poaceae which contain 1-kestose, a specific tri-saccharide. The accumulation of significant quantities of sucrose in all investigated plants, RFOs in Caryophyllaceae plants and 1-kestose in Poaceae plants in response to chilling stress (4 °C for 48 h with a long day photoperiod, 20/4 h) indicates that those compounds participate in the stress response. The common sugar accumulating in cold stress response and probably most important for chilling tolerance of four investigated plants species seems to be sucrose. On the other hand, the accumulation of above-mentioned carbohydrates during chilling stress can be a return to sugars metabolism, occurring in natural environmental conditions. No changes in d-pinitol concentrations were observed in the tissues of C. alpinum and C. quitensis plants subjected to both low and elevated temperatures, which probably rules out the protective effects of d-pinitol in response to cold stress.
Highlights
Polar plants have developed specific anatomic and physiological traits which enable them to survive in extreme environments (Parnikoza et al 2011)
Sucrose levels increased for 24 h in C. alpinum, but prolonged chilling followed by heating lowered sucrose concentrations (Fig. 1a)
The accumulation of sucrose in early response to chilling stress was found in tissues of Haberlea rhodopensis, a resurrection species with extreme resistance to desiccation, stress-sensitive Arabidopsis thaliana and stress-tolerant Thellungiella halophyla (Benina et al 2013)
Summary
Polar plants have developed specific anatomic and physiological traits which enable them to survive in extreme environments (Parnikoza et al 2011). Resistance to low temperatures, salinity and UV radiation are important determinants of plant survival. In the harsh polar (Antarctic and Arctic) environments, the number of indigenous flowering plants species is very limited. In the Antarctic, only two species grow: Colobanthus quitensis (Caryophyllaceae) and Deschampsia antarctica (Poaceae). C. quitensis and D. antarctica have developed unique anatomical structures which enable them to adapt to severe climates, including xerophytic leaves (Romero et al 1999), structural plasticity of chloroplasts and mitochondria (Giełwanowska 2003; Giełwanowska and Szczuka 2005) as well as organs with highly effective photosynthetic function at low temperatures (Bravo et al 2007).
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