Elevated CO2-induced changes in mesophyll conductance and anatomical traits in wild type and carbohydrate-metabolism mutants of Arabidopsis

Abstract Decreases in photosynthetic rate, stomatal conductance (gs), and mesophyll conductance (gm) are often observed under elevated CO2 conditions. However, which anatomical and/or physiological factors contribute to the decrease in gm is not fully understood. Arabidopsis thaliana wild-type and carbon-metabolism mutants (gwd1, pgm1, and cfbp1) with different accumulation patterns of non-structural carbohydrates were grown at ambient (400 ppm) and elevated (800 ppm) CO2. Anatomical and physiological traits of leaves were measured to investigate factors causing the changes in gm and in the mesophyll resistance (expressed as the reciprocal of mesophyll conductance per unit chloroplast surface area facing to intercellular space, Sc/gm). When grown at elevated CO2, all the lines showed increases in cell wall mass, cell wall thickness, and starch content, but not in leaf thickness. gm measured at 800 ppm CO2 was significantly lower than at 400 ppm CO2 in all the lines. Changes in Sc/gm were associated with thicker cell walls rather than with excess starch content. The results indicate that the changes in gm and Sc/gm that occur in response to elevated CO2 are independent of non-structural carbohydrates, and the cell wall represents a greater limitation factor for gm than starch.

Download Full-text

The unusual cell wall of the Lyme disease spirochaete Borrelia burgdorferi is shaped by a tick sugar

Nature Microbiology ◽

10.1038/s41564-021-01003-w ◽

2021 ◽

Vol 6 (12) ◽

pp. 1583-1592

Author(s):

Tanner G. DeHart ◽

Mara R. Kushelman ◽

Sherry B. Hildreth ◽

Richard F. Helm ◽

Brandon L. Jutras

Keyword(s):

Cell Wall ◽

Lyme Disease ◽

Borrelia Burgdorferi ◽

Cell Walls ◽

Structural Strength ◽

Cell Envelope ◽

Wild Type ◽

Tick Vector ◽

Cell Wall Alteration ◽

Main Component

AbstractPeptidoglycan—a mesh sac of glycans that are linked by peptides—is the main component of bacterial cell walls. Peptidoglycan provides structural strength, protects cells from osmotic pressure and contributes to shape. All bacterial glycans are repeating disaccharides of N-acetylglucosamine (GlcNAc) β-(1–4)-linked to N-acetylmuramic acid (MurNAc). Borrelia burgdorferi, the tick-borne Lyme disease pathogen, produces glycan chains in which MurNAc is occasionally replaced with an unknown sugar. Nuclear magnetic resonance, liquid chromatography–mass spectroscopy and genetic analyses show that B. burgdorferi produces glycans that contain GlcNAc–GlcNAc. This unusual disaccharide is chitobiose, a component of its chitinous tick vector. Mutant bacteria that are auxotrophic for chitobiose have altered morphology, reduced motility and cell envelope defects that probably result from producing peptidoglycan that is stiffer than that in wild-type bacteria. We propose that the peptidoglycan of B. burgdorferi probably evolved by adaptation to obligate parasitization of a tick vector, resulting in a biophysical cell-wall alteration to withstand the atypical torque associated with twisting motility.

Download Full-text

Cytokinesis in fra2 Arabidopsis thaliana p60-katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

10.20944/preprints202101.0226.v1 ◽

2021 ◽

Author(s):

Emmanuel Panteris ◽

Anna Kouskouveli ◽

Dimitris Pappas ◽

Ioannis-Dimosthenis S. Adamakis

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Cell Walls ◽

Higher Plants ◽

Cell Plate ◽

Wild Type ◽

Microtubule Organization ◽

Root Cells ◽

Wall Formation ◽

In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate, to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), while deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy, in root cells of the fra2 Arabidopsis thaliana mutant. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls appeared also faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild-type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild-type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

Download Full-text

Arabidopsis cell wall composition determines disease resistance specificity and fitness

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2010243118 ◽

2021 ◽

Vol 118 (5) ◽

pp. e2010243118 ◽

Cited By ~ 1

Author(s):

Antonio Molina ◽

Eva Miedes ◽

Laura Bacete ◽

Tinguaro Rodríguez ◽

Hugo Mélida ◽

...

Keyword(s):

Cell Wall ◽

Disease Resistance ◽

Plant Cell ◽

Cell Walls ◽

Plant Cell Walls ◽

Wild Type ◽

Glycome Profiling ◽

Enhanced Resistance ◽

Trade Offs ◽

Resistance Specificity

Plant cell walls are complex structures subject to dynamic remodeling in response to developmental and environmental cues and play essential functions in disease resistance responses. We tested the specific contribution of plant cell walls to immunity by determining the susceptibility of a set of Arabidopsis cell wall mutants (cwm) to pathogens with different parasitic styles: a vascular bacterium, a necrotrophic fungus, and a biotrophic oomycete. Remarkably, most cwm mutants tested (29/34; 85.3%) showed alterations in their resistance responses to at least one of these pathogens in comparison to wild-type plants, illustrating the relevance of wall composition in determining disease-resistance phenotypes. We found that the enhanced resistance of cwm plants to the necrotrophic and vascular pathogens negatively impacted cwm fitness traits, such as biomass and seed yield. Enhanced resistance of cwm plants is not only mediated by canonical immune pathways, like those modulated by phytohormones or microbe-associated molecular patterns, which are not deregulated in the cwm tested. Pectin-enriched wall fractions isolated from cwm plants triggered immune responses in wild-type plants, suggesting that wall-mediated defensive pathways might contribute to cwm resistance. Cell walls of cwm plants show a high diversity of composition alterations as revealed by glycome profiling that detect specific wall carbohydrate moieties. Mathematical analysis of glycome profiling data identified correlations between the amounts of specific wall carbohydrate moieties and disease resistance phenotypes of cwm plants. These data support the relevant and specific function of plant wall composition in plant immune response modulation and in balancing disease resistance/development trade-offs.

Download Full-text

Overproduction of Chloroplast Glyceraldehyde-3-Phosphate Dehydrogenase Improves Photosynthesis Slightly under Elevated [CO2] Conditions in Rice

Plant and Cell Physiology ◽

10.1093/pcp/pcaa149 ◽

2020 ◽

Author(s):

Yuji Suzuki ◽

Keiki Ishiyama ◽

Misaki Sugawara ◽

Yuka Suzuki ◽

Eri Kondo ◽

...

Keyword(s):

Oryza Sativa ◽

Elevated Co2 ◽

Transgenic Rice ◽

Starch Content ◽

Co2 Assimilation ◽

Wild Type ◽

Rice Plants ◽

Gapdh Activity ◽

Low Co2 ◽

Transgenic Rice Plants

Abstract Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) limits the regeneration of ribulose 1,5-bisphosphate (RuBP) in the Calvin–Benson cycle. However, it does not always limit the rate of CO2 assimilation. In the present study, the effects of overproduction of GAPDH on the rate of CO2 assimilation under elevated [CO2] conditions, where the capacity for RuBP regeneration limits photosynthesis, were examined in transgenic rice (Oryza sativa). GAPDH activity was increased to 3.2- and 4.5-fold of the wild-type levels by co-overexpression of the GAPDH genes, GAPA and GAPB, respectively. In the transgenic rice plants, the rate of CO2 assimilation under elevated [CO2] conditions increased by approximately 10%, whereas that under normal and low [CO2] conditions was not affected. These results indicate that overproduction of GAPDH is effective in improving photosynthesis under elevated [CO2] conditions, although its magnitude is relatively small. By contrast, biomass production of the transgenic rice plants was not greater than that of wild-type plants under elevated [CO2] conditions, although starch content tended to increase marginally.

Download Full-text

Ultrastructure of a palmelloid-forming strain of Chlamydomonas eugametos

Canadian Journal of Botany ◽

10.1139/b78-285 ◽

1978 ◽

Vol 56 (19) ◽

pp. 2348-2356 ◽

Cited By ~ 5

Author(s):

Kazuo Nakamura ◽

Douglas F. Bray ◽

Emile B. Wagenaar

Keyword(s):

Cell Wall ◽

Cell Walls ◽

Transitional Region ◽

Chloroplatinic Acid ◽

Cell Wall Formation ◽

Body Structure ◽

Wild Type ◽

Adhesive Properties ◽

Chlamydomonas Eugametos ◽

Unicellular Green Alga

A palmelloid-forming mutant of the unicellular green alga Chlamydomonas eugametos has been studied ultrastructurally. The repetition, within the palmelloid envelope, of four-celled groups surrounded by wall layers suggests that normal asexual cytokinesis occurs but successive cell generations are unable to separate. Individual palmelloid cells are smaller than wild-type cells and possess flagella which are short (1–2 μm) and occasionally bulbous at the tip but appear normal with regard to internal microtubular, transitional region, and basal body structure. The association of granules with the outer surface of the palmelloid envelope and the tendency of palmelloids to form large aggregates in culture indicate a change in the adhesive properties of the cell walls of this mutant. A comparison of the ultrastructure of mutant palmelloids with previously described chloroplatinic-acid-induced palmelloids shows that the two types differ in both flagellar development and in the extent of cell wall formation.

Download Full-text

Cytokinesis in fra2 Arabidopsis thaliana p60-Katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

International Journal of Molecular Sciences ◽

10.3390/ijms22031405 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1405

Author(s):

Emmanuel Panteris ◽

Anna Kouskouveli ◽

Dimitris Pappas ◽

Ioannis-Dimosthenis S. Adamakis

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Cell Walls ◽

Higher Plants ◽

Cell Plate ◽

Wild Type ◽

Microtubule Organization ◽

Root Cells ◽

Wall Formation ◽

In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast have been reported to occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), in root cells of the fra2 Arabidopsis thaliana loss-of-function mutant. In addition, deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls also appeared faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

Download Full-text

Carbon source dependent differences in the composition of the cell walls of the basidiomycete Picnoporus cinnabarinus

Canadian Journal of Microbiology ◽

10.1139/m77-199 ◽

1977 ◽

Vol 23 (9) ◽

pp. 1313-1317 ◽

Cited By ~ 1

Author(s):

J. A. Cury ◽

Déa Amaral

Keyword(s):

Cell Wall ◽

Carbon Source ◽

Cell Walls ◽

Amino Sugars ◽

Enzymatic Analysis ◽

Wild Type ◽

Monokaryotic Strain ◽

Morphological Differences ◽

Isolated Cell

A wild-type monokaryotic strain of Picnoporus cinnabarinus grown on glucose produced shorter and thicker hyphae than cultures grown on acetate. Colonies from glucose media were smaller and more compact than acetate-grown colonies. Chemical and enzymatic analysis of the isolated cell wall of both morphological types showed that the amount of amino sugars and the ratio glucosamine:galactosamine were higher in the acetate-grown cells. This may be the cause of morphological differences observed.

Download Full-text

Xylem Anatomy and Cell Wall Ultrastructure of Nicotiana Tabacum After Lignin Genetic Modification Through Transcriptional Activator EgMYB2

IAWA Journal ◽

10.1163/22941932-90000093 ◽

2012 ◽

Vol 33 (3) ◽

pp. 269-286 ◽

Cited By ~ 2

Author(s):

Veronica De Micco ◽

Katia Ruel ◽

Jean-Paul Joseleau ◽

Jacqueline Grima-Pettenati ◽

Giovanna Aronne

Keyword(s):

Cell Wall ◽

Genetic Modification ◽

Cell Walls ◽

Lignin Content ◽

Transcriptional Activator ◽

Myb Transcription Factor ◽

Wild Type ◽

Reduced Frequency ◽

Light Fluorescence ◽

R2r3 Myb

The transcriptional activator EgMYB2, which belongs to the large R2R3 MYB transcription factor family, plays a major role in the coordinated control of genes in the lignin biosynthetic pathway. Given that lignin genetic modification can lead to xylem alterations compromising vascular functionality, we characterised wood anatomical properties of two transgenic tobacco lines over-expressing EgMYB2, using light, fluorescence, confocal, transmission electron microscopy, immunocytochemical labelling and digital image analysis. Transgenic wood, compared with wild type, was characterised by both reduced frequency of larger vessels and lower vessel grouping; these traits are known to have physiological implications in terms of water transport efficiency and safety against embolism. Transgenic wood also appeared denser due to the occurrence of thicker cell walls and higher incidence of fibres than wild type. Increased lignin content was accompanied by a concomitant increase in cellulose and xylan, but no alterations in the usual distribution of guaiacyl and syringyl units in secondary cell walls were observed. Altogether, these results show that EgMYB2 is a master regulator controlling the synthesis of the three major polymers of the secondary cell wall and that its overexpression has significant influence on quantitative anatomical traits of wood which affect its functional properties.

Download Full-text

The Relationship Between Variability of Cell Wall Mass of Earlywood and Latewood Tracheids in Larch Tree-Rings, the Rate of Tree-Ring Growth and Climatic Changes

Holzforschung ◽

10.1515/hf.2003.001 ◽

2003 ◽

Vol 57 (1) ◽

pp. 1-7 ◽

Cited By ~ 11

Author(s):

P. P. Silkin ◽

A. V. Kirdyanov

Keyword(s):

Cell Wall ◽

Tree Ring ◽

Cell Walls ◽

Cell Mass ◽

Ring Width ◽

Tree Ring Width ◽

Radial Cell ◽

Wall Mass ◽

Larch Tree ◽

Mass Accumulation

Summary Mass accumulation dynamics in earlywood and latewood cell walls of larch from northern regions of Central Siberia are investigated and correlations among cell mass of different tree-ring zones, radial tracheid sizes and tree-ring width are found. A linear relationship exists between cell wall mass and radial cell size. The deviation of cell mass from the regression line (index of mass deviation) and the mean density of the respective tree-ring zone are similarly functionally dependent on the radial cell size and reflect the realization of the potential determined during the period of cell formation. There is a critical value of larch tree-ring width in relation to cell mass. For the tree-rings with width less than this critical value the difference in the mass of earlywood and latewood cells increases with decreasing tree-ring width.The cell wall mass correlates with the monthly temperatures of June and July. Under favorable growing conditions tracheids with similar mass of cell walls are formed in earlywood and latewood, while under unfavorable conditions cell wall mass accumulation in latewood is severly limited. A comparative analysis of the cell wall mass in earlywood and latewood indicates that mass accumulation is independent of the switching processes from earlywood production to the production of latewood.

Download Full-text

Reduced Cell Size and Cell Wall Components of Apple Softening before Ripening on the Tree

HortScience ◽

10.21273/hortsci.39.6.1227 ◽

2004 ◽

Vol 39 (6) ◽

pp. 1227-1230 ◽

Cited By ~ 1

Author(s):

Dong Geun Choi ◽

Song Joong Yun

Keyword(s):

Cell Wall ◽

Cell Size ◽

Cell Walls ◽

Morphological Changes ◽

Sugar Content ◽

Free Sugar ◽

Fruit Softening ◽

Intercellular Spaces ◽

Wall Mass ◽

Wall Components

The softening of fruit dramatically reduces its market value, especially when this occurs on the tree before ripening. The causes of fruit softening, before ripening, were examined through anatomical and phytochemical comparative analyses between normal fruit, fruit softened on the tree, and stored fruit. The typical morphological changes that occurred with the fruit included early senescence and decreased firmness. The decrease in firmness of softening fruit was due to smaller cell sizes but larger intercellular spaces. The water and free sugar content of the fruit flesh, as well as the weight and sugar content of the cell walls, were significantly lower in softening fruit. Conversely, uronic acid levels and β-galactosidase activity were slightly higher in the softening compared to normal fruit, but the latter was lower than in stored fruit. The results indicated that reduced cell size and cell wall mass were major changes occurring during fruit softening on the tree before ripening, suggesting a difference in the softening mechanisms in ripening and stored fruit.

Download Full-text