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„Inovace a zvýšení atraktivity studia biofyziky “, reg. č.: CZ.1.07/2.2.00/15.0309
Phototropin signaling
in chloroplast movements
Prof. Halina GABRYŚ
Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and
Biotechnology, Jagiellonian University, Kraków, Poland
14. 4. 2014, 14:00
seminar room in F2 building
Centre of Region Haná
To optimize conditions for photosynthesis chloroplasts are in constant
motion in most plants. They accumulate in weakly illuminated regions of
the cell and avoid regions exposed to strong light. In the mesophyll of
vascular land plants, these orientation movements are controlled only by
blue light. In Arabidopsis thaliana, two photoreceptors, phototropin1
(phot1) and phototropin2 (phot2), control the accumulation response, with
the latter active at higher fluency rates. Phot2 alone controls the
avoidance response. The signalling pathway downstream of phototropins
is largely unknown both at the level of signalling target(s) and mediating
species: signal carriers and/or modulators. Chloroplasts move passively,
driven by forces operating outside the organelles. While the participation
of actin cytoskeleton in the movement mechanism is unequivocal, the
mode of actin involvement remains debatable. Our recent studies have
been aimed at determining more exact roles of low molecular species
suggested as secondary messengers in the signal transduction: Ca2+
ions and elements of the phosphoinositide system.