scholarly journals Coalescence and directed anisotropic growth of starch granule initials in subdomains of Arabidopsis thaliana chloroplasts

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Léo Bürgy ◽  
Simona Eicke ◽  
Christophe Kopp ◽  
Camilla Jenny ◽  
Kuan Jen Lu ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Enzyme Activities ◽  
Starch Granule ◽  
Imaging Techniques ◽  
Thylakoid Membranes ◽  
Living Cells ◽  
Anisotropic Growth ◽  
Starch Granules ◽  
Glucose Storage ◽  
Granule Surface

AbstractLiving cells orchestrate enzyme activities to produce myriads of biopolymers but cell-biological understanding of such processes is scarce. Starch, a plant biopolymer forming discrete, semi-crystalline granules within plastids, plays a central role in glucose storage, which is fundamental to life. Combining complementary imaging techniques and Arabidopsis genetics we reveal that, in chloroplasts, multiple starch granules initiate in stromal pockets between thylakoid membranes. These initials coalesce, then grow anisotropically to form lenticular granules. The major starch polymer, amylopectin, is synthesized at the granule surface, while the minor amylose component is deposited internally. The non-enzymatic domain of STARCH SYNTHASE 4, which controls the protein’s localization, is required for anisotropic growth. These results present us with a conceptual framework for understanding the biosynthesis of this key nutrient.

scholarly journals Starch Granule Size and Morphology of Arabidopsis thaliana Starch-Related Mutants Analyzed during Diurnal Rhythm and Development

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5859
Author(s):  
Qingting Liu ◽  
Yuan Zhou ◽  
Joerg Fettke
Keyword(s):  
Arabidopsis Thaliana ◽  
Starch Granule ◽  
Granule Size ◽  
High Temporal Resolution ◽  
Starch Granules ◽  
Transitory Starch ◽  
Young Leaves ◽  
Size And Morphology ◽  
Safranin O

Transitory starch plays a central role in the life cycle of plants. Many aspects of this important metabolism remain unknown; however, starch granules provide insight into this persistent metabolic process. Therefore, monitoring alterations in starch granules with high temporal resolution provides one significant avenue to improve understanding. Here, a previously established method that combines LCSM and safranin-O staining for in vivo imaging of transitory starch granules in leaves of Arabidopsis thaliana was employed to demonstrate, for the first time, the alterations in starch granule size and morphology that occur both throughout the day and during leaf aging. Several starch-related mutants were included, which revealed differences among the generated granules. In ptst2 and sex1-8, the starch granules in old leaves were much larger than those in young leaves; however, the typical flattened discoid morphology was maintained. In ss4 and dpe2/phs1/ss4, the morphology of starch granules in young leaves was altered, with a more rounded shape observed. With leaf development, the starch granules became spherical exclusively in dpe2/phs1/ss4. Thus, the presented data provide new insights to contribute to the understanding of starch granule morphogenesis.

scholarly journals Mass Spectrometric Analysis Reveals Remnants of Host–Pathogen Molecular Interactions at the Starch Granule Surface in Wheat Endosperm

2010 ◽  
Vol 100 (9) ◽  
pp. 848-854 ◽  
Author(s):  
Michael L. Wall ◽  
Heather L. Wheeler ◽  
Jeffrey Smith ◽  
Daniel Figeys ◽  
Illimar Altosaar
Keyword(s):  
Molecular Interactions ◽  
Plant Pathogens ◽  
Magnaporthe Grisea ◽  
Starch Granule ◽  
Surface Proteins ◽  
Molecular Evidence ◽  
Starch Granules ◽  
Wheat Seed ◽  
Host Pathogen ◽  
Granule Surface

The starch granules of wheat seed are solar energy-driven deposits of fixed carbon and, as such, present themselves as targets of pathogen attack. The seed's array of antimicrobial proteins, peptides, and small molecules comprises a molecular defense against penetrating pathogens. In turn, pathogens exhibit an arsenal of enzymes to facilitate the degradation of the host's endosperm. In this context, the starch granule surface is a relatively unexplored domain in which unique molecular barriers may be deployed to defend against and inhibit the late stages of infection. Therefore, it was compelling to explore the starch granule surface in mature wheat seed, which revealed evidence of host–pathogen molecular interactions that may have occurred during grain development. In this study, starch granules from the soft wheat Triticum aestivum cv. AC Andrew and hard wheat T. turgidum durum were isolated and water washed 20 times, and their surface proteins were digested in situ with trypsin. The peptides liberated into the supernatant and the peptides remaining at the starch granule surface were separately examined. In this way, we demonstrated that the identified proteins have a strong affinity for the starch granule surface. Proteins with known antimicrobial activity were identified, as well as several proteins from the plant pathogens Agrobacterium tumefaciens, Pectobacterium carotovorum, Fusarium graminearum, Magnaporthe grisea, Xanthomonas axonopodis, and X. oryzae. Although most of these peptides corresponded to uncharacterized hypothetical proteins of fungal pathogens, several peptide fragments were identical to cytosolic and membrane proteins of specific microbial pathogens. During development and maturation, wheat seed appeared to have resisted infection and lysed the pathogens where, upon desiccation, the molecular evidence remained fixed at the starch granule surface.

scholarly journals PII1: a protein involved in starch initiation that determines granule number and size in Arabidopsis chloroplast

2018 ◽  
Author(s):  
Camille Vandromme ◽  
Corentin Spriet ◽  
David Dauvillée ◽  
Adeline Courseaux ◽  
Jean-Luc Putaux ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Growth Rates ◽  
Starch Granule ◽  
Length Distribution ◽  
Soluble Starch ◽  
Starch Granules ◽  
Wild Type ◽  
Granule Formation ◽  
Chain Length Distribution ◽  
Priming Process

AbstractThe initiation of starch granule formation is still poorly understood. However, soluble starch synthase 4 (SS4) appears to be a major component of this process since it is required to synthetize the correct number of starch granules in the chloroplasts of Arabidopsis thaliana plants. A yeast-2-hybrid screen allowed the identification of several putative SS4 interacting partners. We identified the product of At4g32190 locus as a chloroplast-targeted PROTEIN INVOLVED IN STARCH INITIATION (named PII1). Arabidopsis mutants devoid of PII1 display an alteration of starch initiation process and accumulate, on average, one starch granule per plastid instead of the 5 to 7 granules found in plastids of wild-type plants. These granules are larger than in wild type and they remain flat and lenticular. pii1 mutants display wild-type growth rates and accumulate standard starch amounts. Moreover, starch characteristics, such as amylopectin chain length distribution, remain unchanged. Our results reveal the involvement of PII1 in starch priming process in Arabidopsis leaves through interaction with SS4.

scholarly journals 3D super-resolved imaging in live cells using sub-diffractive plasmonic localization of hybrid nanopillar arrays

Nanophotonics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2847-2859
Author(s):  
Soojung Kim ◽  
Hyerin Song ◽  
Heesang Ahn ◽  
Seung Won Jun ◽  
Seungchul Kim ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Imaging Techniques ◽  
Optical Loss ◽  
Super Resolution ◽  
Living Cells ◽  
Live Cells ◽  
Complex Biological System ◽  
Observation Volume ◽  
Resolution Imaging ◽  
Nanopillar Arrays

AbstractAnalysing dynamics of a single biomolecule using high-resolution imaging techniques has been had significant attentions to understand complex biological system. Among the many approaches, vertical nanopillar arrays in contact with the inside of cells have been reported as a one of useful imaging applications since an observation volume can be confined down to few-tens nanometre theoretically. However, the nanopillars experimentally are not able to obtain super-resolution imaging because their evanescent waves generate a high optical loss and a low signal-to-noise ratio. Also, conventional nanopillars have a limitation to yield 3D information because they do not concern field localization in z-axis. Here, we developed novel hybrid nanopillar arrays (HNPs) that consist of SiO2 nanopillars terminated with gold nanodisks, allowing extreme light localization. The electromagnetic field profiles of HNPs are obtained through simulations and imaging resolution of cell membrane and biomolecules in living cells are tested using one-photon and 3D multiphoton fluorescence microscopy, respectively. Consequently, HNPs present approximately 25 times enhanced intensity compared to controls and obtained an axial and lateral resolution of 110 and 210 nm of the intensities of fluorophores conjugated with biomolecules transported in living cells. These structures can be a great platform to analyse complex intracellular environment.

Co-ordinate regulation of genes involved in storage lipid mobilization in Arabidopsis thaliana

2001 ◽  
Vol 29 (2) ◽  
pp. 283-286 ◽  
Author(s):  
E. L. Rylott ◽  
M. A. Hooks ◽  
I. A. Graham
Keyword(s):  
Arabidopsis Thaliana ◽  
Enzyme Activities ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Molecular Genetic ◽  
Regulation Of Gene Expression ◽  
Growth Period ◽  
Malate Synthase ◽  
The Glyoxylate Cycle

Molecular genetic approaches in the model plant Arabidopsis thaliana (ColO) are shedding new light on the role and control of the pathways associated with the mobilization of lipid reserves during oilseed germination and post-germinative growth. Numerous independent studies have reported on the expression of individual genes encoding enzymes from the three major pathways: β-oxidation, the glyoxylate cycle and gluconeogenesis. However, a single comprehensive study of representative genes and enzymes from the different pathways in a single plant species has not been done. Here we present results from Arabidopsis that demonstrate the co-ordinate regulation of gene expression and enzyme activities for the acyl-CoA oxidase- and 3-ketoacyl-CoA thiolasemediated steps of β-oxidation, the isocitrate lyase and malate synthase steps of the glyoxylate cycle and the phosphoenolpyruvate carboxykinase step of gluconeogenesis. The mRNA abundance and enzyme activities increase to a peak at stage 2, 48 h after the onset of seed germination, and decline thereafter either to undetectable levels (for malate synthase and isocitrate lyase) or low basal levels (for the genes of β-oxidation and gluconeogenesis). The co-ordinate induction of all these genes at the onset of germination raises the possibility that a global regulatory mechanism operates to induce the expression of genes associated with the mobilization of storage reserves during the heterotrophic growth period.

Production and Characterization of Porous Starch Granule and Poly(butylene adipate-co-terephthalate) Blend as a Bio-Composite

2012 ◽  
Vol 550-553 ◽  
pp. 1513-1521
Author(s):  
Sirirat Thothong ◽  
Klanarong Sriroth ◽  
Rattana Tantatherdtam ◽  
Amnat Jarerat
Keyword(s):  
Starch Granule ◽  
Rice Starch ◽  
Starch Granules ◽  
Screw Extruder ◽  
Elongation At Break ◽  
Single Screw ◽  
Single Screw Extruder ◽  
Scanning Electron ◽  
Granular Starch

To improve the miscibility of native rice starch granules and poly(butylene adipate-co-terephthalate)(PBAT), rice starch was hydrolyzed by a mixture of α-amylase and amyloglucosidase. The obtained porous rice granular starch was then mechanically blended with PBAT by single screw extruder. Many pits and holes on the surface of starch granules were observed by scanning electron microscopy (SEM). The rough surface of the rice starch granules improved the compatibility of the polymers in the blends, which consequently increased the tensile strength and the elongation at break. In addition, SEM also revealed that the porous granules were homogeneously distributed in the polymer matrix with no appearance of gaps.

scholarly journals KARAKTERISTIK PATI BERPORI MIKRO DARI TAPIOKA HASIL PERLAKUAN AMILASE SEBAGAI AGEN PENJERAPAN MINYAK [The Characteristic of Microporous Tapioca Starch After Amylase Treatment For Oil Adsorbent Agent]

2020 ◽  
Vol 25 (2) ◽  
pp. 71
Author(s):  
Dwi Ajias Pramasari ◽  
Dewi Sondari ◽  
Danang Sudarwoko Adi ◽  
Bernadeta Ayu Widyaningrum ◽  
Anugerah Fajar ◽  
...  
Keyword(s):  
Oil Palm ◽  
Functional Group ◽  
Starch Granule ◽  
Granule Size ◽  
The Other ◽  
Partial Hydrolysis ◽  
Color Analysis ◽  
Tapioca Starch ◽  
Granule Surface ◽  
The One

Microporous starch can be used as oil adsorbent agent. The microporous starch can be produced through partial hydrolysis at temperature below gelatinization point using amylase. On the other hand, the study of amylase produced from Indonesian sea microbe, especially Brevibacterium sp. was rarely studied. Therefore, this paper discusses the tapioca characteristic made from Brevibacterium sp. amylase (treatment A) and commercial amylase (treatment B) as oil adsorbent agent. The result showed that the yield from treatment A and B was 74.65% and 12.75% while the starch granule size was 14.60 μm and 12,59 μm. The adsorbent test showed adsorption level of oil palm were 91,08% and 142,14% while for olive oil were 94,70% and 133,17%, for treatment A and B, respectively. The morphological test showed the presence of pori on the granule surface for both treatments with FTIR assessment showed no significant change in chemical functional group for both treatments. The color analysis showed almost similar brightness level between two treatments. In the end, microporous starch of treatment A has prospect as oil adsorbent agent like the one from commercial amylase

scholarly journals Alpha Carbonic Anhydrase 5 Mediates Stimulation of ATP Synthesis by Bicarbonate in Isolated Arabidopsis Thylakoids

2021 ◽  
Vol 12 ◽  
Author(s):  
Tatiana P. Fedorchuk ◽  
Inga A. Kireeva ◽  
Vera K. Opanasenko ◽  
Vasily V. Terentyev ◽  
Natalia N. Rudenko ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Arabidopsis Thaliana ◽  
Carbonic Anhydrase ◽  
Atp Synthesis ◽  
Thylakoid Membranes ◽  
Wild Type ◽  
Gene Encoding ◽  
Mutant Lines ◽  
Stimulation Of ◽  
Soluble Carbonic Anhydrase

We studied bicarbonate-induced stimulation of photophosphorylation in thylakoids isolated from leaves of Arabidopsis thaliana plants. This stimulation was not observed in thylakoids of wild-type in the presence of mafenide, a soluble carbonic anhydrase inhibitor, and was absent in thylakoids of two mutant lines lacking the gene encoding alpha carbonic anhydrase 5 (αCA5). Using mass spectrometry, we revealed the presence of αCA5 in stromal thylakoid membranes of wild-type plants. A possible mechanism of the photophosphorylation stimulation by bicarbonate that involves αCA5 is proposed.

scholarly journals Characterization of Suspension Cultures of Arabidopsis thaliana (L.) Heynh Cells with Altered Expression of the Gene of Alternative Mitochondrial Oxidase Aox1a and Analysis of their Frost Resistance

2021 ◽  
Vol 35 ◽  
pp. 3-18
Author(s):  
A. V. Stepanov ◽  
◽  
S. A. Kashin ◽  
N. S. Zabanova ◽  
O. A. Fedotova ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Suspension Culture ◽  
Mitochondrial Respiration ◽  
Frost Resistance ◽  
Alternative Oxidase ◽  
Uncoupling Protein ◽  
Living Cells ◽  
Subzero Temperature ◽  
Wild Type ◽  
Culture Cells

The enzyme alternative cyanide-resistant oxidase (AOX) localized in mitochondria is involved in the processes of plant adaptation to various unfavorable biotic and abiotic factors. Transfer of electrons from ubiquinone to oxygen by alternative oxidase has a nonprotonmotive character and, by bypassing two sites of H+ pumping in complexes III and IV, lowers the energy efficiency of respiration and energy of electron flow through AOX is released as heat. In this work, we characterized heterotrophic suspension cultures of Arabidopsis thaliana (L.) Heynh cells obtained from seeds of plants with altered (reduced (AS-12 line) and increased (XX-2 line)) expression of the alternative oxidase gene AOX1a and studied their viability under subzero temperature (-10 °С for 3, 6, 9 hours). Cell viability and reactive oxygen species (ROS) production were assessed using fluorescence microscopy with fluorescein diacetate (FDA) and propidium iodide (PI) for cell viability measurement and H2DCF-DA for ROS measurement. The proportion of living cells was calculated as the proportion of FDApositive and PI-negative cells. Differences between the studied lines were determined in the content of mitochondrial proteins of the respiratory chain (AOX, COXII, NDB) and uncoupling protein (UCP), as well as in the intensity of formation of ROS and frost resistance. The obtained results confirmed the higher content of the AOX protein and its high contribution to mitochondrial respiration in line XX-2. Suspension culture cells of the AS-12 line showed a decrease in the AOX protein content and its contribution to mitochondrial respiration, compared to the wild type (Col-0) and line XX-2. Simultaneously with a decrease in the AOX protein content in the AS-12 cell culture, an increase in the content of the uncoupling protein UCP and subunit II of cytochrome oxidase (COXII) was observed. ROS generation was reduced in cell cultures of both XX-2 and AS-12. The obtained results indicate that the cells of the wildtype (Col-0) suspension culture were subjected to the most significant effect of subzero temperature. Long-term exposure (for 9 h) under -10 °С revealed significant differences in the viability of wild-type culture cells and lines with altered AOX1a gene expression. Cells of line XX-2 with an increased content of AOX turned out to be more resistant to subzero temperature compared to wild-type and AS-12 cells. However, while the proportion of living cells in the culture of the AS-12 line 48 h after exposure remained at the same level as immediately after it, in the suspension culture of the wild type cell death developed over time. The obtained results indicate the importance of alternative oxidase in the development of frost resistance in plant cell.

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