Research
Mechanism of auxin transport
Plant hormone auxin is a key
regulator of many developmental processes in plants. It plays a major role in
control of temporal and spatial aspects of plant growth and, as such, it
co-ordinates plant development. In contrast to other plant growth regulators
(plant hormones), in some tissues auxin molecules are transported to long
distances through plant body and their transport is strictly directional
(polar). Mechanism of the polar auxin transport is based on physical-chemical
properties of auxin molecules and on their molecular forms inside and outside
cells. It is a very complex and dynamic process with many levels of regulation.
Our laboratory focuses on the molecular mechanism of polar auxin transport and
on the ways of its regulation. More…
Metabolism and physiological function of cytokinins
Cytokinins are naturally occurring phytohormones that act in concert with
auxins to regulate cell division and differentiation and thus efficiently
control plant growth and development. Transient enhancement of auxin in relation
to cytokinin levels induces root formation while the opposite shift results in
shoot formation. Re-establishment of the two hormone quantitative ratios
(hormonal homeostasis) is essential for further development of induced events.
Our research is focused on the metabolic regulation of intra- and extracellular
levels of cytokinins and their interactions with auxins. According to our
working hypothesis (see the scheme) the adjustment of hormonal homeostasis after
a transient enhancement of cytokinin levels due to their biosynthesis or uptake
from cell exterior is reached by stimulation of cytokinin metabolic degradation,
reversible or irreversible inactivation by conjugation with sugars or alanine
and by binding to specific binding proteins. The validity of this hypothesis is
being experimentally verified using in vitro cultures of plant cells and tissues
as well as in intact plants. More…
Plant Hormones Functions in Ontogenesis and Interactions with the Environment
Plants have evolved complex systems of defence against, and
adaption to, the variable and often potentially damaging environmental
conditions to which they are exposed during their growth and development. Due to
their sessile character, plants need to respond very dynamically to various
abiotic (drought, extreme temperatures, high light intensity) as well as biotic
stresses (pest and pathogen attacks). Our laboratory has focused on the
elucidation of plant defence mechanisms, with the aim to contribute to the
development of effective strategies to enhance stress tolerance of plants.
Drought belongs to the most frequent abiotic stresses. Plants cope with water
stress by preferential protection of upper leaves and apex. Gradual degradation
of macromolecules takes place in lower leaves, nutrients being transported to
upper leaves. Plant hormones cytokinins increase the sink strength. We found
that stress induced polarization of tobacco plants has been mediated by the
establishment of cytokinin gradient in favour of upper leaves. This gradient is
during severe water deficit strengthened by the stimulation of cytokinin
degradation by cytokinin oxidase/dehydrogenase (CKX) in lower leaves. More…
Analytical methods – determination of plant hormones
The analytical unit of our
laboratory works on improving of existing and developing of new analytical
procedures for purification, quantitation and metabolic profiling of plant
hormones and some other bioactive substances of plant origin. More…