Studies on a new role of plant sterols, regulation of activity of some proteins involved in photosynthesis

Ecdysteroids are insect hormones, involved in larvae development, ecdysis, pupation etc. The role of ecdysteroids in plants is unknown, although ecdysteroids occur in some plants in a relatively large amount. Brassinosteroids are plant hormones regulating growth, biomass production and response to stress. Their role in animals is still unclear. Our unique approach allowed us to identify plant proteins revealing high affinity to these compounds. This was achieved by exploitation of bioaffinity chromatography using polymeric carriers with the above sterols or their analogues bound by oriented immobilisation. To find the reason for the presence of oxysterol binding domains in these proteins, we tried to influence their biological activity by the free sterols. The results clearly show, that among others the activity of the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) can be increased.

The finding is of particular interest, because RuBisCO is unique by converting inorganic carbon dioxide into organic compounds, thus being the basis of life on Earth. The reaction rate of this enzyme is quite low, this fact being compensated by its high content in plant leaves; it represents between 30 to 50% of all proteins in green plant biomass, which means it is the most abundant enzyme in the biosphere. We consider these results being of high importance, because any increase of photosynthesis yield would represent a tremendous increase in crop production and CO₂ fixation. Also other enzymes that we found to have affinity to oxysterols, are involved in photosynthetic processes and we intend to prove our hypothesis that ecdysteroids role is fine tuning of these enzymes.

Phytoremediation / rhizoremediation - use of plants in removal of toxic compounds from soil, sediments and water

We are studying the role of plants (the green liver of the planet) in cleaning the polluted environment. By natural mechanisms, plants can take up many different toxic metals or organic compounds, concentrate and detoxify them. The mechanisms, enzymes involved, products formed and their toxicity are studied, together with interaction of plants and rhizosphere microorganisms. Plants select which bacteria will be present in soil, and can induce their degradative abilities. We study the effect of plant compounds on bacteria in contaminated soil, including metagenomic studies (genome is the set of genes of a given organisms, while metagenome is the set of genes present in the given environment, including those of bacteria which we are still unable to cultivate in laboratory). Our main target xenobiotic compound are polychlorinated biphenyls (PCB).

Genetically modified plants

Transgenic plants specifically tailored for phytoremediation purposes are prepared to speed-up the slow process of plant uptake and removal of unwanted compounds, by introduction of bacterial degradative genes for organic compounds, or by cloning special peptides with high heavy-metal binding capacity into plants. For crop protection purposes, GM-plants were prepared, emitting insect sexual pheromones, to disrupt insect mating behavior, thus preventing the excess use of pesticides, while the protected crop does not need to be GM.