73 research outputs found
Modifications of Phytohormone Metabolism Aimed at Stimulation of Plant Growth, Improving Their Productivity and Tolerance to Abiotic and Biotic Stress Factors
No full textDue to the growing human population, the increase in crop yield is an important challenge for modern agriculture. As abiotic and biotic stresses cause severe losses in agriculture, it is also crucial to obtain varieties that are more tolerant to these factors. In the past, traditional breeding methods were used to obtain new varieties displaying demanded traits. Nowadays, genetic engineering is another available tool. An important direction of the research on genetically modified plants concerns the modification of phytohormone metabolism. This review summarizes the state-of-the-art research concerning the modulation of phytohormone content aimed at the stimulation of plant growth and the improvement of stress tolerance. It aims to provide a useful basis for developing new strategies for crop yield improvement by genetic engineering of phytohormone metabolism
Practical aspects of the measurements of non-photochemical chlorophyll fluorescence quenching in green microalgae Chlamydomonas reinhardtii using Open FluorCam
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Gaining insight into mechanisms of nonphotochemical quenching of chlorophyll fluorescence in Chlamydomonas reinhardtii via the observation of dark-induced state transitions
No full textPhotosynthetic organisms are usually exposed to fluctuating light, and therefore they evolved mechanisms enabling fast acclimation to changing light conditions. Among them, two important ones are energy-dependent quenching of excited chlorophyll (qE) and state transitions (ST). qE is a photoprotective mechanism regulated by pH gradient across thylakoid membranes, in which excessive energy is dissipated as heat. ST are rearrangements of antenna systems regulated by the phosphorylation of LHC II complexes. Both of these mechanisms result in changes in NPQ parameters. In the present article, changes of NPQ in the green microalga Chlamydomonas reinhardtii were evaluated in the dark period, after various lengths of actinic light exposure, and after the application of the thiol reducing reagent dithiotreitol and the cyt inhibitor 2' ,4' -dinitrophenyl ether of 2-iodo-4-nitro-thymol. The impact of the length of actinic light exposure on xanthophyll cycle progression in C. reinhardtii was also analysed. The obtained results enabled us to gain more insight into the nonphotochemical quenching of chlorophyll fluorescence in model organism C. reinhardtii, i.e. the role of zeaxanthin-dependent quenching and chlororespiration-induced pH gradient, and the inhibitory action of tested compounds on state transitions in this species
Studies on antioxidant functions and biosynthetic pathways of isoprenoid quinones in plants
No full textResults of the measurements of the impact of four 1,4-naphthoquinones on compounds of Chlamydomonas reinhardtii
No full textResults of the measurements of the impact of four 1,4-naphthoquinones on compounds of Chlamydomonas reinhardtii (long incubation in low light plus short incubation in high light and darkness) and the experiment with in vitro incubation, pasked in the zip fil
Gaining Insight into Mechanisms of Nonphotochemical Quenching of Chlorophyll Fluorescence in Chlamydomonas reinhardtii via the Observation of Dark-induced State Transitions
No full textPhotosynthetic organisms are usually exposed to fluctuating light, and therefore they evolved mechanisms enabling fast acclimation to changing light conditions. Among them, two important ones are energy-dependent quenching of excited chlorophyll (qE) and state transitions (ST). qE is a photoprotective mechanism regulated by pH gradient across thylakoid membranes, in which excessive energy is dissipated as heat. ST are rearrangements of antenna systems regulated by the phosphorylation of LHC II complexes. Both of these mechanisms result in changes in NPQ parameters. In the present article, changes of NPQ in the green microalga Chlamydomonas reinhardtii were evaluated in the dark period, after various lengths of actinic light exposure, and after the application of the thiol reducing reagent dithiotreitol and the cyt b6f inhibitor 2' ,4' -dinitrophenyl ether of 2-iodo-4-nitro-thymol. The impact of the length of actinic light exposure on xanthophyll cycle progression in C. reinhardtii was also analysed. The obtained results enabled us to gain more insight into the nonphotochemical quenching of chlorophyll fluorescence in model organism C. reinhardtii, i.e. the role of zeaxanthin-dependent quenching and chlororespiration-induced pH gradient, and the inhibitory action of tested compounds on state transitions in this species
Cyanobacteria use both p-hydroxybenozate and homogentisate as a precursor of plastoquinone head group
No full textUntil recently it was believed that cyanobacterial pathway of plastoquinone biosynthesis is analogical to that of higher plants. In plants, homogentisate is a precursor of the hydrophilic head group of plastoquinone. Recent experiments on Synechocystis sp. PCC 6803 have shown that this organism takes advantage of another pathway that resembles ubiquinone biosynthetic pathway of α-, β- and γ-proteobacteria. In the present work, we have analysed the content of plastoquinone, tocopherol and tocopherolquinone in six strains of cyanobacteria and compared the obtained results with search for genes of homologues of enzymes participating in tocopherol and ubiquinone biosynthesis. We have shown that inhibition of homogentisate synthesis lowers tocopherol content but does not affect plastoquinone synthesis in Synechococcus sp. PCC 7002. Inhibitors of p-hydroxybenzoate and homogentisate prenyltransferases selectively influenced plastoquinone and tocopherol biosynthesis in Synechocystis sp. PCC 6803. Radiolabelled 14C-p-hydroxybenzoate was incorporated into plastoquinone by three cyanobacteria species investigated. Although, when ^14C-homogentisate was added to growth medium, the labelled plastoquinone was found in extracts of the cyanobacteria. Synechocystis sp. PCC 6803 grown in the presence of ^14C-homogentisate showed also small amounts of the labelled tyrosine, suggesting that cyanobacteria are able to incorporate exogenously added homogentisate into shikimate pathway.
Keyword
Occurrence, biosynthesis and function of isoprenoid quinones
No full textAbstractIsoprenoid quinones are one of the most important groups of compounds occurring in membranes of living organisms. These compounds are composed of a hydrophilic head group and an apolar isoprenoid side chain, giving the molecules a lipid-soluble character. Isoprenoid quinones function mainly as electron and proton carriers in photosynthetic and respiratory electron transport chains and these compounds show also additional functions, such as antioxidant function. Most of naturally occurring isoprenoid quinones belong to naphthoquinones or evolutionary younger benzoquinones. Among benzoquinones, the most widespread and important are ubiquinones and plastoquinones. Menaquinones, belonging to naphthoquinones, function in respiratory and photosynthetic electron transport chains of bacteria. Phylloquinone K1, a phytyl naphthoquinone, functions in the photosynthetic electron transport in photosystem I. Ubiquinones participate in respiratory chains of eukaryotic mitochondria and some bacteria. Plastoquinones are components of photosynthetic electron transport chains of cyanobacteria and plant chloroplasts. Biosynthetic pathway of isoprenoid quinones has been described, as well as their additional, recently recognized, diverse functions in bacterial, plant and animal metabolism
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