ORIGINAL PAPER Temperature-dependent impact of 24-epibrassinolide on the fatty acid composition and sugar content in winter oilseed rape callus Anna Janeczko Æ Katarzyna Hura Æ Andrzej Skoczowski Æ Iwona Idzik Æ Jolanta Biesaga-Kos ´cielniak Æ El _ zbieta Niemczyk Received: 22 October 2007 / Revised: 28 June 2008 / Accepted: 7 July 2008 / Published online: 5 August 2008 Ó Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako ´w 2008 Abstract The aim of this experiment was to study the effect of 24-epibrassinolide (BR 27 ) on fatty acids compo- sition and sugar content in winter oilseed rape callus cultured at 20 and 5°C. Studies have showed that BR 27 action is highly temperature-dependent. The increase in sugar content (sucrose, glucose and fructose) by BR 27 in concentration 100 nM was observed only in calli cultured at 20°C. At 5°C, quite the opposite effect of BR 27 action was observed; where cold increased the sugar content, BR 27 decreased it. BR 27 at 20°C had a similar effect on the fatty acid composition of phospholipids (PL) as the cold in the process of frost hardening of oilseed rape calli. BR 27 decreased the 16:0, 18:1 and 18:2 and increased the 18:3 fatty acid content. At 5°C, BR 27 (100 nM) generally did not inﬂuence the fatty acid composition of PL. In case of digalactosyl diacylglycerols and monogalactosyl diacylglycerols, the inﬂuence of BR 27 on the fatty acid composition is ambiguous but still depends on temperature. Keywords 24-Epibrassinolide Á Calli Á Oilseed rape Á Fatty acids Á Sugars Abbreviations PL Phospholipids DG Digalactosyl diacylglycerols MG Monogalactosyl diacylglycerols BR 27 24-Epibrassinolide (according to Mandava 1988; Zullo and Kohout 2004) BR Brassinosteroids 16:0 Palmitic acid 18:0 Stearic acid 18:1 Oleic acid 18:2 Linoleic acid 18:3 Linolenic acid Introduction Brassinosteroids (BR) are a relatively new class of plant steroid hormones discovered in 1979 (Grove et al. 1979; Bishop and Yokota 2001). Their action is accompanied by stimulation of growth processes, but they can also protect plants against many stressors, such as heavy metals, salt, heat shock and cold (Krishna 2003; Jan- eczko et al. 2005). The mechanism of BR action in plants is still not fully explained; extremely little is known about their interaction with temperature. As our previous results show, 24-epibrassinolide (BR 27 ) exerted opposite effects on cell membranes of oilseed rape at different temperatures; at 20°C, it increased, while at 2°C, it decreased the membrane permeability (Janeczko et al. 2007). The aim of the present experiment was to study the relationship between the temperature of oilseed rape growth and the inﬂuence of BR 27 on biochemical changes in cells. As a model system, oilseed rape tissue culture, either cold-hardened or non-hardened, has been Communicated by S. Lewak. A. Janeczko (&) Á A. Skoczowski Á I. Idzik Á J. Biesaga-Kos ´cielniak Á E. Niemczyk The Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, 21 Niezapominajek Street, 30-239 Krako ´w, Poland e-mail: ania@belanna.strefa.pl K. Hura Department of Plant Physiology, Faculty of Agriculture, Agricultural University of Krako ´w, 3 Podlu _ zna Street, 30-239 Krako ´w, Poland 123 Acta Physiol Plant (2009) 31:71–79 DOI 10.1007/s11738-008-0202-2