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Start Over Creator Pospíšilová, J.

2. Effects of abscisic acid or benzyladenine on pigment contents, chlorophyll fluorescence, and chloroplast ultrastructure during water stress and after rehydration

Creator:
Haisel, D., Pospíšilová, J., Synková, H., Schnablová, R., and Baťková, P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Beta vulgaris, carotenoids, Nicotiana tabacum, Phaseolus vulgaris, starch content, xanthophylls, and Zea mays
Language:
Multiple languages
Description:
With the aim to contribute to the elucidation of the role of phytohormones in response of plants to adverse environmental conditions, seedlings of Phaseolus vulgaris, Nicotiana tabacum, Beta vulgaris, and Zea mays were supplied with water, 100 µM abscisic acid (ABA), or 10 µM N6-benzyladenine (BA) immediately before imposition of water stress (WS). In all four species, contents of chlorophylls (Chls) and carotenoids were markedly decreased during WS and after rehydration only in plants pre-treated with water but not in those pre-treated with ABA or BA. Contents of pigments of xanthophyll cycle increased during WS more in plants pre-treated with ABA or BA than in those pre-treated with water, but the degree of their de-epoxidation was highest in the later. Similarly, the efficiency of photosystem 2, determined as variable to maximal Chl fluorescence ratio, was not markedly decreased in bean plants pre-treated with ABA or BA in contrast to those pre-treated with water. The imposed WS was not severe enough to damage chloroplast ultrastructure. However, different changes in a size of starch inclusions were observed. In bean plants, the amount of starch increased considerably in plants pre-treated with water, while it decreased in BA pre-treated plants and no change was found in ABA pre-treated ones. The starch content declined under WS in sugar beet and tobacco plants but only moderate changes were found in ABA or BA pre-treated plants. Thus the application of BA and especially of ABA reduced the negative effects of subsequent WS. and D. Haisel ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Gas exchange and in vivo chlorophyll fluorescence in potato and tobacco plantlets in vitro as affected by various concentrations of 6-benzylaniinopurine

Creator:
Pospíšilová, J., Čatský, J., Macháčková, I., and Solárová, J.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Application of 6-benzylaminopurine (BAP) into cultivation medium of potato and tobacco plantlets caused changes in their growth, morphology and photosynthetic parameters in dependence on the plant species and the concentration ušed. The stimulating effect of BAP added to the cultivation medium was found only at very low BAP concentrations (up to 0.01 g m'^ in tobacco and 0.1 g m'^ in potato plantlets). BAP induced only a very slight tendency to increasing chlorophyll (Chl) a+b content and the ratios Chl alb, ChLcarotenoids and net photosynthetic rate/dark respiration rate {P^íIRd) in both plant species. Also the increase of the photochemical efficiency of photosystem 2 as indicated by the ratio of variable to maximal fluorescence (FyT^) and was not statistically significant and was found only in potato plantlets. The stomatal transpiration rate {E^ in tobacco plantlets increased with increasing BAP concentrations up to 0.1 g m'^. However, this was a rather negative effect as it increased a danger of plantlet wilting. In both plant species the BAP concentration of 1.0 g m-^ inhibited growth of plantlet roots; their shoots had altered morphology, their P^, light respiration rate {R\), E^, P^IRy, ratio, Chl contents and parameters of in vivo fluorescence (Fy/Fn,, qp, Rfd) decreased and CO2 compensation concentration increased. This negative effect of BAP was more pronounced in tobacco than in potato plantlets. The above mentioned changes in photosynthetic parameters in plantlets treated with BAP corresponded to the changes in photosynthetic parameters in transgenic plants of the same species with T-DNA carrying gene 4 and resulting from increased level of endogenous cytokinins. However, the application of BAP lead to a decrease in endogenous cytokinins level and thus the effects described are probably due to the action of BAP itself
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

5. Interaction of cytokinins and abscisic acid during regulation of stomatal opening in bean leaves

Creator:
Pospíšilová, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
benzyladenine, net photosynthetic rate, Phaseolus vulgaris, stomatal conductance, transpiration rate, and water stress
Language:
Multiple languages
Description:
Effects of benzyladenine (BA) and abscisic acid (ABA) applied separately or simultaneously on parameters of gas exchange of Phaseolus vulgaris L. leaves were studied. In the first two experimental sets) 100 μM ABA and 10 μM BA were applied to plants sufficiently supplied with water. Spraying of leaves with ABA decreased stomatal conductance (gs) and in consequence transpiration rate (E) and net photosynthetic rate (PN) already 1 h after application, but 24 h after application the effect almost disappeared. 10 μM BA slightly decreased gas exchange parameters, but in simultaneous application with ABA reversed the effect of ABA. Immersion of roots into the same solutions markedly decreased gas exchange parameters and 24 h after ABA application the stomata were completely closed. The effect of ABA was ameliorated by simultaneous BA application, particularly after 1-h treatment. In the third experimental set, plants were pre-treated by immersing roots into water, 1 μM BA, or 100 μM ABA for 24 h and then the halves of split root system were dipped into different combinations of 1 μM BA, 100 μM ABA, and water. In plants pre-treated with ABA all gas exchange parameters were small and they did not differ in plants treated with H2O+H2O, H2O+BA, or BA+BA. In plants pre-treated with BA or H2O, markedly lower values of PN were found when both halves of roots were immersed in ABA. Further, the effects of pre-treatment of plants with water, 1 μM BA, 100 μM ABA, or ABA+BA on the development of water stress induced by cessation of watering and on the recovery after rehydration were followed. ABA markedly decreased gas exchange parameters at the beginning of the experiment, but in its later phase the effect was compensated by delay in development of water stress. BA also delayed development of water stress and increased PN in water-stressed leaves. BA reversed the effect of ABA at mild water stress. Positive effects of BA and ABA pre-treatments were observed also after rehydration.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

6. Responses of tobacco plantlets to change of irradiance during transfer from in vitro to ex vitro conditions

Creator:
Semorádová, Š., Synková, H., and Pospíšilová, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
acclimation, chlorophyll content, fluorescence, net photosynthetic rate, Nicotiana tabacum, stomatal conductance, transpiration rate, and xanthophyll cycle pigments
Language:
Multiple languages
Description:
Chlorophyll a fluorescence kinetics, net photosynthetic rate (PN), water relations, and photosynthetic pigment contents were studied during acclimation of in vitro grown tobacco to higher irradiance (HL; 700 μmol m-2 s-1). Plantlets were grown on medium containing sucrose in glass vessels (G-plants) or in Magenta boxes (M-plants) with better CO2 supply in the latter ones. The effect of HL was studied either (1) in plantlets grown under original in vitro conditions (closed vessels), (2) in in vitro plantlets exposed to ambient CO2 concentration (covers removed), or (3) in plantlets transplanted to ex vitro into pots with sand and nutrient solution. Higher PN, and fraction of closed photosystem 2 (PS2) centres (1 - qP), and lower content of xanthophyll cycle pigments were found in M-plants compared to G-plants. HL treatment caused photoinhibition particularly in plants kept in closed vessels. This was indicated by the decrease in the ratio of Fv/Fm and by the increase in non-photochemical quenching, 1 - qp, and content of xanthophyll cycle pigments. Better CO2 supply ensured by the removal of closure lead to the moderate reduction of symptoms of photoinhibition, although stomatal conductance (gs), transpiration rate (E), and PN were negatively affected. The main reason was the decrease in relative air humidity, which caused similar reduction of PN, E, and gs after the transfer of plantlets to ex vitro. Nevertheless, plant response to HL seemed not to be affected by any possible root injury caused by transfer to ex vitro. The differences in contents of xanthophyll cycle pigments, degree of de-epoxidation, PN, and quenching parameters between M- and G-plantlets were still significant 7 d after ex vitro transfer and HL acclimation. and Š. Semorádová, H. Synková, J. Pospíšilová.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public