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Start Over Creator Haisel, D.

2. Content of carotenoids during ageing and senescence of tobacco leaves with genetically modulated life-span

Creator:
Procházková, D., Haisel, D., and Wilhelmová, N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
cytokinin, reactive oxygen species, and xanthophylls
Language:
Multiple languages
Description:
We exploited leaves of tobacco (Nicotiana tabacum L., cv. Wisconsin 38) with introduced chimeric construct consisting of SAG12 promoter fused with ipt gene for cytokinin synthesis and therefore prolonged life-span. As a control we used its wild type. In 12-week-old plants, the first leaves of control plants showed senescence symptoms at the time of sampling. Carotenoid content decreased with increasing leaf age both in control and in transgenic plants. On the other hand, the first leaves of transgenic plants demonstrated better antioxidant capacity represented by carotenoids compared to the leaves of control plants of the same age. They stayed still green at this age. and D. Procházková, D. Haisel, N. Wilhelmová.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. 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

4. Effects of exogenous nitric oxide on photosynthesis

Creator:
Procházková, D., Haisel, D., Wilhelmová, Naďa, Pavlíková, Daniela, and Száková, Jiřina
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, chlorophyll fluorescence, chloroplast, nitration, nitrotyrosine, 2, and 581
Language:
Multiple languages
Description:
Nitric oxide (NO) is an important signalling molecule with diverse physiological functions in plants. In plant cell, it is synthesised in several metabolic ways either enzymatically or nonenzymatically. Due to its high reactivity, it could be also cytotoxic in dependence on concentration. Such effects could be also mediated by NO-derived compounds. However, the role of NO in photosynthetic apparatus arrangement and in photosynthetic performance is poorly understood as indicated by a number of studies in this field with often conflicting results. This review brings a short survey of the role of exogenous NO in photosynthesis under physiological and stressful conditions, particularly of its effect on parameters of chlorophyll fluorescence. and D. Procházková ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

6. Photosynthesis and protective mechanisms during ageing in transgenic tobacco leaves with over-expressed cytokinin oxidase/dehydrogenase and thus lowered cytokinin content

Creator:
Mýtinová, Z., Haisel, D., and Wilhelmová, N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, Nicotiana tabacum, photosynthetic efficiency, senescence, and xanthophyll cycle
Language:
Multiple languages
Description:
The content of cytokinins (CKs), the plant inhibitors of the final phase of plant development, senescence, is effectively controlled by irreversible degradation catalysed by cytokinin oxidase/dehydrogenase (CKX). In transgenic tobacco, denoted as AtCKX, with over-expressed CKX causing lowered CK content, we investigated changes in the time courses of chlorophyll (Chl) and xanthophyll (violaxanthin, antheraxanthin, zeaxanthin, neoxanthin, and lutein) contents. We also determined parameters of slow Chl fluorescence kinetics such as minimum Chl fluorescence yield in the darkadapted state F0, maximum quantum yield of PS2 photochemistry (Fv/Fm), maximum ratio of quantum yields of photochemical and concurrent non-photochemical processes in photosystem 2 (PS2), Fv/F0, non-photochemical quenching (NPQ), and effective quantum yield of photochemical energy conversion in PS2 (Φ2). We used three different developmental leaf stages, old, mature, and young, and compared this with time courses of these characteristics in leaves with natural CK levels. The parameters Fv/Fm, Fv/F0, and Φ2 were unchanged during ageing in AtCKX plants in contrast to control ones where a significant decrease in old leaves was found. In control plants F0 increased during ageing, but in the oldest leaf a considerable decrease was observed. This could indicate progressive damage to PS2 reaction centres and then detachment and rapid degradation of Chl. This is in agreement with time course of Chl content. NPQ decreased with age and was similar in both plant types. We observed a decline of xanthophyll contents in the oldest leaves in both plant types, but the contents were enhanced in AtCKX compared to control plants, especially of neoxanthin. The higher xanthophyll contents in the transgenic plants contribute to a better photoprotection and the fluorescence parameters indicated that photosynthetic apparatus was in better condition compared to control and it consequently postponed the onset of leaf senescence. and Z. Mýtinová, D. Haisel, N. Wilhelmová.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

7. The ultrastructure of chloroplasts, content of photosynthetic pigments, and photochemical activity of maize (Zea mays L.) as influenced by different concentrations of the herbicide amitrole

Creator:
Pechová, R., Kutík, J., Holá, D., Kočová, M., Haisel, D., and Vičánková, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
3-amino-1,2,4-triazole, carotenoids, chlorophylls, Hill reaction, and photosystems 1 and 2
Language:
Multiple languages
Description:
The effect of three different concentrations of amitrole (AM), a bleaching herbicide affecting carotenogenesis, on chloroplast ultrastructure, photosynthetic pigment contents, and photochemical activity was studied in two maize genotypes differing in photosynthetic characteristics. The content of photosynthetic pigments in leaves of plants treated with low (20 μM) AM concentration was similar to control plants and no damaging effect of the herbicide on the ultrastructure of either mesophyll (MC) or bundle-sheath (BSC) cell chloroplasts was observed. Higher (60 and 120 μM) concentrations of AM caused a significant decrease in the content of carotenoids (especially xanthophylls), which was followed by photooxidative destruction of chlorophylls and some alterations of chloroplast ultrastructure. MC chloroplasts appeared more sensitive to the damaging effect of AM compared to BSC chloroplasts. A significant decrease in the amount of both granal and intergranal thylakoids in MC chloroplasts was observed with the increasing concentration of AM. As regards BSC chloroplasts, rapid decrease in the volume density of starch inclusions was found in plants treated with higher concentrations of AM. When 120 μM AM was used, both MC and BSC chloroplasts contained just a few thylakoid membranes that were strongly altered. The changes in the ultrastructure of MC chloroplasts were accompanied by the changes in their photochemical activity. The formation of chloroplast protrusions after treatment of plants with AM as well as in control plants was also observed. and R. Pechová ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

8. Ultrastructure and dimensions of chloroplasts in leaves of three maize (Zea mays L.) inbred lines and their F1 hybrids grown under moderate chilling stress

Creator:
Kutík, J., Holá, D., Kočová, M., Rothová, O., Haisel, D., Wilhelmová, N., and Tichá, I.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
bundle sheath cells, electron microscopy, genotypes, heterosis, intra-specific variability, mesophyll cells, peripheral reticulum, plastoglobuli, stereology, and thylakoids
Language:
Multiple languages
Description:
Influence of moderate chilling stress on vascular bundle sheath cell (BSC) and especially mesophyll cell (MC) chloroplasts of mature maize leaves was studied by electron microscopy and stereology. Plants of two inbred lines of maize, differing in their photosynthetic activity, and their F1 hybrids were cultivated during autumn in heated or unheated glasshouse. Generally, chilling temperatures resulted mainly in the decrease in stereological volume density (VD) of both granal and intergranal thylakoids of MC chloroplasts, while the ratio of granal to all thylakoids (granality) was less affected. The VD of peripheral reticulum and plastoglobuli usually increased after cold treatment of plants. The volume of MC chloroplasts usually increased under chilling stress, the shape of the chloroplasts changed only slightly. The ultra-structure of chloroplasts differed between individual genotypes; chilling-stressed hybrid plants showed positive heterosis particularly in the granal thylakoids' VD of MC chloroplasts. and J. Kutík ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public