Brasinosteroidy as factors modifying the molecular dynamics of model membranes and membranes isolated from barley plants.

During their life cycle, plants are usually exposed to different environmental factors: abiotic
(extreme temperature, a lack or excess of water, too low or too intense light) and biotic (pathogens,
parasites). Plants have developed various acclimation strategies to counteract the negative effects of
abiotic stresses (including extreme temperature stress) and the cell membrane is an important
element in these strategies. During acclimation to changing temperature conditions, modifications
in the cell membrane fluidity are connected with changes in the proportion of unsaturated fatty
acids, which results in a rearrangement of the membrane structure and its properties. Membrane
properties may also be modified by incorporating various components into their structure, for
example, tocopherols or sterols. Many of the physiological phenomena that occurs in cells is
controlled by multidirectional effect of hormones on the metabolism of plants, which is also the
basis for the adaptability of organisms in order to function in changing environmental conditions.
Brassinosteroids (plant steroid hormones) belongs to the group of hormones that are involved
among others in regulating of plant growth and plant metabolism in stressful conditions. Their
function in plants is still being explained and relatively little is known about their impact on the
plant cell membrane properties. Considering the role of membranes as the first cellular line to react
to changing temperatures, the aim of the proposed project is to broaden the knowledge about
changes in physicochemical properties of cell membranes during the plant acclimation to low/high
temperature and the influence of brassinosteroids on these properties. Studies of brassinosteroid
content in cell membranes will also be performed. The object of studies will be barley – species of
economic importance. Results obtained in the project will enrich knowledge about mechanisms of
action of brassinosteroids - the hormones that have perspectives to be used in agriculture for
protection of crop plants against environmental stress.