Isayenkov S. Molecular-genetic and functional characterization of membrane transporter involved in regulation of salt and drought tolerance in plants and arsenic detoxification

Object of study: the transport processes of minerals and As by membrane transport proteins and their role in regulation of ion and osmotic homeostasis, salinity stress, phytotoxic effects. Subject of research: the molecular organization, functional specialization, physiological role of plant membrane transport proteins, in particular protein families of HKT, NHX, TPK, PT and subfamily NIP, in conditions of salinity and osmotic stresses, potassium deficiency, and arcenite removal yeast ScACR3 membrane system in conditions As compounds exposure. It was shown, that over-expression of HvHKT2;1 leads to increased salt tolerance by reinforcing the salt-including behaviour of barley. According to cladistical analysis of selected NHX transporter sequences, the appearance of new (AtNHX3-like) clade was discovered. The elevation of salt tolerance occurred in HvNHX2 expressing tobacco plans. It was discovered the induction of HvNHX4 expression occurred only in salt stress condition. Our data demonstrate, that TPK1 has a role in intracellular K+ homeostasis affecting seedling growth, the stomata closure and regulation of osmotic stress. The cellular localization of OsTPKa and OsTPKb channels was different. The rice OsTPKa and OsTPKb have different vacuolar specialisation and might play important role of in regulation of salt and osmotic stress, seed formation and plant development. The different subcellular localization was observed for the tobacco TPK channel - NtTPK1a and NtTPK1b. Our results therefore strongly suggest that in addition to AtTPK1, AtTPK2 and AtTPK5, OsTPKa and OsTPKb can form functional K+ transport systems in E. coli and as such may also form functional channels in planta. Our for the first time suggest that AtNIP7;1 forms part of an AsIII uptake pathway in A. thaliana. According to the data of our study the heterologous expression of yeast ACR3 endows plants with greater arsenic resistance, but does not lower significantly arsenic tissue levels.