EFFECTS OF ANION CHANNEL BLOCKERS NPPB AND DIDS ON TOBACCO POLLEN TUBE GROWTH AND ITS MITOCHONDRIA STATE
M. A. Breygina,1 A. V. Smirnova, M. V. Maslennikov,
N. P. Matveeva, I. P. Yermakov
Moscow State University, School of Biology, Plant Physiology Department;
1 e-mail: pollen-ions@rambler.ru
Influence of anion channel blockers NPPB and DIDS on pollen tube growth and its mitochondria functioning was studied by means of fluorescence microscopy and flow
cytometry. NPPB (40 μM) blocked pollen tube growth completely, but did not change its diameter. DIDS (20-80 μM) caused pollen tube swelling and bursting,
suggesting that DIDS-sensitive channels take part in the regulation of pollen tube osmotic balance. The osmotic effect of low DIDS concentration (20 μM) was not
accompanied by changes in the tube growth rate. The mapping of membrane potential on the pollen tube plasmalemma using Di-4-ANEPPS revealed the involvement of
NPPB-sensitive but not DIDS-sensitive anion channels in the maintenance of the longitudinal membrane potential gradient along the tube surface. The study of isolated pollen
mitochondria showed that DIDS increased their capacity to take up potential-dependent dye DiOC5(3), i. e. caused hyperpolarization of mitochondrial
membranes. At the same time DIDS influenced on intramitochondrial ROS content and excretion of ROS from mitochondria. Thus, NPPB and DIDS differently influenced on
transmembrane potential distribution along pollen tube plasmalemma, on its osmotic balance, and on mitochondria functioning. This set of data suggests that pollen tube
growth is dependent on activity of anion channels that differ in localization and functions.
Key words: pollen tube, membrane potential, pollen tube mitochondria
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