Effect of thiosulphinates contained in garlic extract on growth, proton fluxes and membrane potential in maize (Zea mays L.) coleoptile segments |
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Authors: | Ma?gorzata Polak Wies?awa Zaborska Zbigniew Tukaj Waldemar Karcz |
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Institution: | (1) Department of Plant Physiology, Faculty of Biology, University of Silesia, Jagiellońska 28, 40032 Katowice, Poland;(2) Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30060 Krak?w, Poland;(3) Department of Plant Physiology, Faculty of Biology, University of Gdańsk, Piłsudskiego 46, 81378 Gdynia, Poland; |
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Abstract: | The effect of thiosulphinates contained in garlic extract (GE) on endogenous growth, growth in the presence of either indoleacetic
acid (IAA) or fusicoccin (FC), and proton extrusion in maize coleoptile segments were studied. In addition, membrane potential
changes at some GE dilutions and the protective effect of dithiothreitol (DTT) against GE toxicity were also determined. It
was found that GE at almost all dilutions studied, when added to the incubation medium inhibited endogenous growth as well
as growth in the presence of either IAA or FC. Simultaneous measurements of growth and external pH indicated that the administration
of GE resulted in a complex change in the pH of the external medium; after an initial transient acidification, pH increased
and reached the maximal value followed by a gradual decrease of medium pH. When IAA or FC was added after preincubation of
the segments in the presence of GE the changes in medium pH were not significantly different from these obtained with GE only.
If the coleoptile segments were first preincubated with GE and subsequently GE was removed, the addition of IAA induced strong
growth and medium acidification. Dithiothreitol added together with GE neutralized the toxic effect of GE on growth of coleoptile
segments incubated in the presence of IAA. The addition of GE to the control medium caused a depolarization of the membrane
potential, the value of witch depended on GE dilution. These results indicate that the toxic effect of GE on growth of plant
cells might be caused by disruption of the catalytic function of the plasma membrane H+-ATPase on formation of the disulfide bonds. |
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