Pregnane derivatives such as pregnenolone or progesterone and many other metabolites are important in mammals where many of them act as hormones including sexual hormones. Much less is known about the presence and functions of pregnane derivatives in plants. The main objectives of this work were (1) to determine the presence of pregnane derivatives in winter wheat (2) verify if there are changes of concentration of pregnane derivatives during wheat growth/development with special attention to vernalisation process (3) to answer the question of whether selected pregnane derivatives are stimulators of wheat development and whether the potential stimulation of this development is accompanied by the expression of the Vrn1 (Vernalisation1) gene. To the best of our knowledge, this is the first report that demonstrates the presence of pregnenolone and 5α-dihydroprogesterone in the leaves and intact crowns of winter wheat. The levels of some of the pregnane derivatives changed during plant growth/development, it was demonstrated that pregnenolone, pregnanolone and 17α-hydroxypregnenolone stimulated wheat development. The changes in the Vrn1 expression are discussed in light of the stimulation of generative development by the pregnane derivatives.

• Keywords
• Vrn1 expression, 5α-dihydroprogesterone, Cold, Pregnenolone, Vernalisation, Winter wheat,
• MeSH
• Plant Leaves growth & development   genetics   metabolism   MeSH
• Pregnanes * MeSH
• Pregnenolone MeSH
• Triticum * genetics   growth & development   metabolism   MeSH
• Gene Expression Regulation, Plant MeSH
• Plant Proteins metabolism   genetics   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Pregnanes * MeSH
• Pregnenolone MeSH
• Plant Proteins MeSH

Winter plants acclimate to frost mainly during the autumn months, through the process of cold acclimation. Global climate change is causing changes in weather patterns such as the occurrence of warmer periods during late autumn or in winter. An increase in temperature after cold acclimation can decrease frost tolerance, which is particularly dangerous for winter crops. The aim of this study was to investigate the role of brassinosteroids (BRs) and BR analogues as protective agents against the negative results of deacclimation. Plants were cold-acclimated (3 weeks, 4 °C) and deacclimated (1 week, 16/9 °C d/n). Deacclimation generally reversed the cold-induced changes in the level of the putative brassinosteroid receptor protein (BRI1), the expression of BR-induced COR, and the expression of SERK1, which is involved in BR signal transduction. The deacclimation-induced decrease in frost tolerance in oilseed rape could to some extent be limited by applying steroid regulators. The deacclimation in plants could be detected using non-invasive measurements such as leaf reflectance, chlorophyll a fluorescence, and gas exchange monitoring.

• Keywords
• 24-epibrassinolide, 28-homocastasterone, BRI1, CO2 assimilation, COR, SERK, brassinosteroid analogues, chlorophyll a fluorescence, frost tolerance, leaf reflectance,
• MeSH
• Acclimatization * MeSH
• Brassica napus * physiology   metabolism   MeSH
• Brassinosteroids * metabolism   MeSH
• Plant Leaves metabolism   physiology   MeSH
• Cold Temperature * MeSH
• Gene Expression Regulation, Plant * MeSH
• Seasons MeSH
• Plant Proteins metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Brassinosteroids * MeSH
• Plant Proteins MeSH

Plants have developed various acclimation strategies in order to counteract the negative effects of abiotic stresses (including temperature stress), and biological membranes are important elements in these strategies. Brassinosteroids (BR) are plant steroid hormones that regulate plant growth and development and modulate their reaction against many environmental stresses including temperature stress, but their role in modifying the properties of the biological membrane is poorly known. In this paper, we characterise the molecular dynamics of chloroplast membranes that had been isolated from wild-type and a BR-deficient barley mutant that had been acclimated to low and high temperatures in order to enrich the knowledge about the role of BR as regulators of the dynamics of the photosynthetic membranes. The molecular dynamics of the membranes was investigated using electron paramagnetic resonance (EPR) spectroscopy in both a hydrophilic and hydrophobic area of the membranes. The content of BR was determined, and other important membrane components that affect their molecular dynamics such as chlorophylls, carotenoids and fatty acids in these membranes were also determined. The chloroplast membranes of the BR-mutant had a higher degree of rigidification than the membranes of the wild type. In the hydrophilic area, the most visible differences were observed in plants that had been grown at 20 °C, whereas in the hydrophobic core, they were visible at both 20 and 5 °C. There were no differences in the molecular dynamics of the studied membranes in the chloroplast membranes that had been isolated from plants that had been grown at 27 °C. The role of BR in regulating the molecular dynamics of the photosynthetic membranes will be discussed against the background of an analysis of the photosynthetic pigments and fatty acid composition in the chloroplasts.

• Keywords
• EPR, barley, brassinosteroids, chloroplast membranes, molecular dynamics, temperature stress,
• MeSH
• Acclimatization MeSH
• Brassinosteroids metabolism   MeSH
• Chloroplasts genetics   metabolism   MeSH
• Photosynthesis MeSH
• Hordeum genetics   physiology   MeSH
• Mutation MeSH
• Cold-Shock Response MeSH
• Heat-Shock Response MeSH
• Molecular Dynamics Simulation MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Brassinosteroids MeSH