scholarly journals Influence of the compatible solute sucrose on thylakoid membrane organization and violaxanthin de-epoxidation

Planta ◽  
2021 ◽  
Vol 254 (3) ◽  
Author(s):  
Reimund Goss ◽  
Christian Schwarz ◽  
Monique Matzner ◽  
Christian Wilhelm
Keyword(s):  
Thylakoid Membrane ◽  
Higher Plants ◽  
Thylakoid Membranes ◽  
Compatible Solute ◽  
In Vitro Assays ◽  
Lipid Phase ◽  
Enzyme Assays ◽  
Membrane Organization ◽  
Lipid Organization

Abstract Main conclusion The compatible solute sucrose reduces the efficiency of the enzymatic de-epoxidation of violaxanthin, probably by a direct effect on the protein parts of violaxanthin de-epoxidase which protrude from the lipid phase of the thylakoid membrane. The present study investigates the influence of the compatible solute sucrose on the violaxanthin cycle of higher plants in intact thylakoids and in in vitro enzyme assays with the isolated enzyme violaxanthin de-epoxidase at temperatures of 30 and 10 °C, respectively. In addition, the influence of sucrose on the lipid organization of thylakoid membranes and the MGDG phase in the in vitro assays is determined. The results show that sucrose leads to a pronounced inhibition of violaxanthin de-epoxidation both in intact thylakoid membranes and the enzyme assays. In general, the inhibition is similar at 30 and 10 °C. With respect to the lipid organization only minor changes can be seen in thylakoid membranes at 30 °C in the presence of sucrose. However, sucrose seems to stabilize the thylakoid membranes at lower temperatures and at 10 °C a comparable membrane organization to that at 30 °C can be observed, whereas control thylakoids show a significantly different membrane organization at the lower temperature. The MGDG phase in the in vitro assays is not substantially affected by the presence of sucrose or by changes of the temperature. We conclude that the presence of sucrose and the increased viscosity of the reaction buffers stabilize the protein part of the enzyme violaxanthin de-epoxidase, thereby decreasing the dynamic interactions between the catalytic site and the substrate violaxanthin. This indicates that sucrose interacts with those parts of the enzyme which are accessible at the membrane surface of the lipid phase of the thylakoid membrane or the MGDG phase of the in vitro enzyme assays.

Regulation of photosystem II by metabolic and environmental factors

1989 ◽  
Vol 323 (1216) ◽  
pp. 269-279 ◽  
Keyword(s):  
Electron Transport ◽  
Higher Plants ◽  
Photosynthetic Electron Transport ◽  
Thylakoid Membranes ◽  
Internal Factors ◽  
Regulatory Processes ◽  
Quenching Analysis ◽  
Intact Chloroplasts ◽  
Rate Of Dissipation

The thylakoid membranes of higher plants possess several mechanisms that control both the distribution and rate of dissipation of absorbed light. These mechanisms, which allow regulation of photosynthetic electron transport in response to alteration in external and internal factors, can be observed as the various processes that quench chlorophyll fluorescence. By using the 'light-doubling techniques’, together with analysis of quenching relaxation, it is possible to assess quantitatively the extents of these regulatory processes and to allow their interrelations to be studied. These techniques can be applied to in vitro systems or to leaves, and can be particularly useful when applied with electron-transport measurements and when models are used to aid interpretation. Results of quenching analysis at different light intensities in isolated thylakoids, intact chloroplasts, protoplasts, algae and leaves of a variety of species are presented.

Response of a Chlorsulfuron-Resistant Biotype ofKochia scopariato Sulfonylurea and Alternative Herbicides

Weed Science ◽  
1993 ◽  
Vol 41 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Lyle F. Friesen ◽  
Ian N. Morrison ◽  
Abdur Rashid ◽  
Malcolm D. Devine
Keyword(s):  
Field Experiments ◽  
Good Control ◽  
Acetolactate Synthase ◽  
In Vitro Assays ◽  
Shoot Biomass ◽  
Wheat Crop ◽  
Enzyme Assays ◽  
Dry Matter Accumulation ◽  
Severe Stunting

Kochia growing on an industrial site where chlorsulfuron was applied repeatedly over several seasons was confirmed to be resistant to chlorsulfuron and several other acetolactate synthase (ALS) -inhibiting herbicides. In growth room experiments, resistant (R) plants were 2 to >180 times more resistant to five sulfonylurea herbicides and one imidazolinone herbicide (imazethapyr) than susceptible (S) plants, as measured by the ratio of dosages required to inhibit shoot dry matter accumulation by 50% (GR50R/S). Similarly, in vitro assays of ALS activity indicated that from 3 to 30 times more herbicide was required to inhibit the enzyme from R plants than from S plants. Results of ALS enzyme assays indicated that R kochia was approximately equally resistant to metsulfuron, triasulfuron, and thifensulfuron, and 2.5 times more resistant to tribenuron than thifensulfuron. However, the response of R kochia growing in a spring wheat crop in the field was not consistent with results of the ALS enzyme assays. In field experiments, thifensulfuron at 32 g ai ha−1had little effect on R kochia. In contrast, metsulfuron, triasulfuron, and tribenuron at 8 g ha−1did not reduce R kochia seedling densities, but caused severe stunting such that 2 mo after treatment the shoot biomass of plants in untreated plots was four times greater than in sprayed plots. Herbicides with alternative modes of action including fluroxypyr, bromoxynil/MCPA ester, dichlorprop/2,4-D ester, and 2,4-D ester provided good control of R kochia in the field. Quinclorac did not reduce kochia densities, but surviving plants were stunted. To delay or avoid development of ALS inhibitor-resistant kochia populations, these alternative herbicides applied alone or in tank mixtures could be incorporated into a herbicide rotation.

scholarly journals Tomato glycosyltransferase Twi1 plays a role in flavonoid glycosylation and defence against virus

2019 ◽  
Author(s):  
Laura Campos ◽  
María Pilar López-Gresa ◽  
Diana Fuertes ◽  
José María Bellés ◽  
Ismael Rodrigo ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Higher Plants ◽  
Plant Defence ◽  
In Vitro Assays ◽  
Tomato Plants ◽  
Transgenic Tomato Plants ◽  
Wilt Virus

Abstract Background: Secondary metabolites play an important role in the plant defensive response. They are produced as a defence mechanism against biotic stress by providing plants with antimicrobial and antioxidant weapons. In higher plants, the majority of secondary metabolites accumulate as glycoconjugates. Glycosylation is one of the commonest modifications of secondary metabolites, and is carried out by enzymes called glycosyltransferases. Results: Here we provide evidence that the previously described tomato wound and pathogen-induced glycosyltransferase Twi1 displays in vitro activity toward the coumarins scopoletin, umbelliferone and esculetin, and the flavonoids quercetin and kaempferol, by uncovering a new role of this gene in plant glycosylation. To test its activity in vivo, Twi1-silenced transgenic tomato plants were generated and infected with Tomato spotted wilt virus. The Twi1-silenced plants showed a differential accumulation of Twi1 substrates and enhanced susceptibility to the virus. Conclusions: Biochemical in vitro assays and transgenic plants generation proved to be useful strategies to assign a role of tomato Twi1 in the plant defence response. Twi1 glycosyltransferase showed to regulate quercetin and kaempferol levels in tomato plants, affecting plant resistance to viral infection.

scholarly journals Tomato glycosyltransferase Twi1 plays a role in flavonoid glycosylation and defence against virus

2019 ◽  
Author(s):  
Laura Campos ◽  
María Pilar López-Gresa ◽  
Diana Fuertes ◽  
José María Bellés ◽  
Ismael Rodrigo ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Higher Plants ◽  
Plant Defence ◽  
In Vitro Assays ◽  
Tomato Plants ◽  
Transgenic Tomato Plants ◽  
Wilt Virus

Abstract Background: Secondary metabolites play an important role in the plant defensive response. They are produced as a defence mechanism against biotic stress by providing plants with antimicrobial and antioxidant weapons. In higher plants, the majority of secondary metabolites accumulate as glycoconjugates. Glycosylation is one of the commonest modifications of secondary metabolites, and is carried out by enzymes called glycosyltransferases. Results: Here we provide evidence that the previously described tomato wound and pathogen-induced glycosyltransferase Twi1 displays in vitro activity toward the coumarins scopoletin, umbelliferone and esculetin, and the flavonoids quercetin and kaempferol, by uncovering a new role of this gene in plant glycosylation. To test its activity in vivo, Twi1-silenced transgenic tomato plants were generated and infected with Tomato spotted wilt virus. The Twi1-silenced plants showed a differential accumulation of Twi1 substrates and enhanced susceptibility to the virus. Conclusions: Biochemical in vitro assays and transgenic plants generation proved to be useful strategies to assign a role of tomato Twi1 in the plant defence response. Twi1 glycosyltransferase showed to regulate quercetin and kaempferol levels in tomato plants, affecting plant resistance to viral infection.

scholarly journals Tomato glycosyltransferase Twi1 plays a role in flavonoid glycosylation and defence against virus

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Laura Campos ◽  
María Pilar López-Gresa ◽  
Diana Fuertes ◽  
José María Bellés ◽  
Ismael Rodrigo ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Higher Plants ◽  
Plant Defence ◽  
In Vitro Assays ◽  
Tomato Plants ◽  
Transgenic Tomato Plants ◽  
Wilt Virus

Abstract Background Secondary metabolites play an important role in the plant defensive response. They are produced as a defence mechanism against biotic stress by providing plants with antimicrobial and antioxidant weapons. In higher plants, the majority of secondary metabolites accumulate as glycoconjugates. Glycosylation is one of the commonest modifications of secondary metabolites, and is carried out by enzymes called glycosyltransferases. Results Here we provide evidence that the previously described tomato wound and pathogen-induced glycosyltransferase Twi1 displays in vitro activity toward the coumarins scopoletin, umbelliferone and esculetin, and the flavonoids quercetin and kaempferol, by uncovering a new role of this gene in plant glycosylation. To test its activity in vivo, Twi1-silenced transgenic tomato plants were generated and infected with Tomato spotted wilt virus. The Twi1-silenced plants showed a differential accumulation of Twi1 substrates and enhanced susceptibility to the virus. Conclusions Biochemical in vitro assays and transgenic plants generation proved to be useful strategies to assign a role of tomato Twi1 in the plant defence response. Twi1 glycosyltransferase showed to regulate quercetin and kaempferol levels in tomato plants, affecting plant resistance to viral infection.

scholarly journals Tomato glycosyltransferase Twi1 plays a role in flavonoid glycosylation and defence against virus

2019 ◽  
Author(s):  
Laura Campos ◽  
María Pilar López-Gresa ◽  
Diana Fuertes ◽  
José María Bellés ◽  
Ismael Rodrigo ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Higher Plants ◽  
Plant Defence ◽  
In Vitro Assays ◽  
Tomato Plants ◽  
Transgenic Tomato Plants ◽  
Wilt Virus

Abstract Background: Secondary metabolites play an important role in the plant defensive response. They are produced as a defence mechanism against biotic stress by providing plants with antimicrobial and antioxidant weapons. In higher plants, the majority of secondary metabolites accumulate as glycoconjugates. Glycosylation is one of the commonest modifications of secondary metabolites, and is carried out by enzymes called glycosyltransferases. Results: Here we provide evidence that the previously described tomato wound and pathogen-induced glycosyltransferase Twi1 displays in vitro activity toward the coumarins scopoletin, umbelliferone and esculetin, and the flavonoids quercetin and kaempferol, by uncovering a new role of this gene in plant glycosylation. To test its activity in vivo, Twi1-silenced transgenic tomato plants were generated and infected with Tomato spotted wilt virus. The Twi1-silenced plants showed a differential accumulation of Twi1 substrates and enhanced susceptibility to the virus. Conclusions: Biochemical in vitro assays and transgenic plants generation proved to be useful strategies to assign a role of tomato Twi1 in the plant defence response. Twi1 glycosyltransferase showed to regulate quercetin and kaempferol levels in tomato plants, affecting plant resistance to viral infection.

scholarly journals Interference of Cd2+ in functioning of the photosynthetic apparatus of higher plants

2014 ◽  
Vol 55 (2) ◽  
pp. 291-304 ◽  
Author(s):  
Tadeusz Baszyński
Keyword(s):  
Photosystem Ii ◽  
Thylakoid Membrane ◽  
Higher Plants ◽  
Photosynthetic Apparatus ◽  
Light Phase ◽  
Membrane Degradation ◽  
Transport Chain ◽  
Photosystem Ii Activity

The actual opinions concerning the role of Cd<sup>2+</sup> in inhibition of photosynthesis have been reviewed. The light phase of photosynthesis, particularly the site of Cd<sup>2+</sup> action in the photosynthetic transport chain has been given the greatest attention. Cd<sup>2+</sup>-induced inhibition of Photosystem II activity as the result of thylakoid membrane degradation has been discussed. The present studies on Cd<sup>2+</sup>-inhibited dark reactions occurring in stroma has been analysed. Attention has been drawn to the fact that the results of studies in vitro are not always compatible with the changes found in the photosynthetic apparatus of higher plants growing in a Cd2 containing medium.

scholarly journals Tomato glycosyltransferase Twi1 plays a role in flavonoid glycosylation and defence against virus

2019 ◽  
Author(s):  
Laura Campos ◽  
María Pilar López-Gresa ◽  
Diana Fuertes ◽  
José María Bellés ◽  
Ismael Rodrigo ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Higher Plants ◽  
Plant Defence ◽  
In Vitro Assays ◽  
Tomato Plants ◽  
Transgenic Tomato Plants ◽  
Wilt Virus

Abstract Background: Secondary metabolites play an important role in the plant defensive response. They are produced as a defence mechanism against biotic stress by providing plants with antimicrobial and antioxidant weapons. In higher plants, the majority of secondary metabolites accumulate as glycoconjugates. Glycosylation is one of the commonest modifications of secondary metabolites, and is carried out by enzymes called glycosyltransferases. Results: Here we provide evidence that the previously described tomato wound and pathogen-induced glycosyltransferase Twi1 displays in vitro activity toward the coumarins scopoletin, umbelliferone and esculetin, and the flavonoids quercetin and kaempferol, by uncovering a new role of this gene in plant glycosylation. To test its activity in vivo, Twi1-silenced transgenic tomato plants were generated and infected with Tomato spotted wilt virus. The Twi1-silenced plants showed a differential accumulation of Twi1 substrates and enhanced susceptibility to the virus. Conclusions: Biochemical in vitro assays and transgenic plants generation proved to be useful strategies to assign a role of tomato Twi1 in the plant defence response. Twi1 glycosyltransferase showed to regulate quercetin and kaempferol levels in tomato plants, affecting plant resistance to viral infection.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

A in Vivo Assay for Standardizing Heparin Preparations

1979 ◽  
Vol 41 (03) ◽  
pp. 576-582
Author(s):  
A R Pomeroy
Keyword(s):  
In Vitro Assays ◽  
British Pharmacopoeia ◽  
In Vitro Method ◽  
Standard Preparation ◽  
Reliable Estimation ◽  
Assay Procedure ◽  
Accuracy And Precision ◽  
Heparin Preparation

SummaryThe limitations of currently used in vitro assays of heparin have demonstrated the need for an in vivo method suitable for routine use.The in vivo method which is described in this paper uses, for each heparin preparation, four groups of five mice which are injected intravenously with heparin according to a “2 and 2 dose assay” procedure. The method is relatively rapid, requiring 3 to 4 hours to test five heparin preparations against a standard preparation of heparin. Levels of accuracy and precision acceptable for the requirements of the British Pharmacopoeia are obtained by combining the results of 3 to 4 assays of a heparin preparation.The similarity of results obtained the in vivo method and the in vitro method of the British Pharmacopoeia for heparin preparations of lung and mucosal origin validates this in vivo method and, conversely, demonstrates that the in vitro method of the British Pharmacopoeia gives a reliable estimation of the in vivo activity of heparin.

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