scholarly journals Starch Granules in Arabidopsis thaliana Mesophyll and Guard Cells Show Similar Morphology but Differences in Size and Number

2021 ◽  
Vol 22 (11) ◽  
pp. 5666
Author(s):  
Qingting Liu ◽  
Xiaoping Li ◽  
Joerg Fettke
Keyword(s):  
Arabidopsis Thaliana ◽  
Starch Synthesis ◽  
Guard Cells ◽  
Morphological Properties ◽  
Fast Method ◽  
Starch Granules ◽  
Mesophyll Cells ◽  
Laser Confocal Scanning Microscopy ◽  
Transitory Starch ◽  
Confocal Scanning

Transitory starch granules result from complex carbon turnover and display specific situations during starch synthesis and degradation. The fundamental mechanisms that specify starch granule characteristics, such as granule size, morphology, and the number per chloroplast, are largely unknown. However, transitory starch is found in the various cells of the leaves of Arabidopsis thaliana, but comparative analyses are lacking. Here, we adopted a fast method of laser confocal scanning microscopy to analyze the starch granules in a series of Arabidopsis mutants with altered starch metabolism. This allowed us to separately analyze the starch particles in the mesophyll and in guard cells. In all mutants, the guard cells were always found to contain more but smaller plastidial starch granules than mesophyll cells. The morphological properties of the starch granules, however, were indiscernible or identical in both types of leaf cells.

scholarly journals The pathway of starch synthesis in Arabidopsis thaliana leaves

2021 ◽  
Author(s):  
Maximilian M.F.F. Fünfgeld ◽  
Wei Wang ◽  
Hirofumi Ishihara ◽  
Stéphanie Arrivault ◽  
Regina Feil ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Sucrose Synthase ◽  
Significant Contribution ◽  
Starch Synthesis ◽  
Classical Pathway ◽  
Mesophyll Cells ◽  
Fluctuating Light ◽  
Leaf Sampling ◽  
Transitory Starch ◽  
Made In

AbstractMany plants accumulate transitory starch reserves in their leaves during the day to buffer their carbohydrate supply against fluctuating light conditions, and to provide carbon and energy for survival at night. It is universally accepted that transitory starch is synthesized from ADP-glucose (ADPG) in the chloroplasts. However, the consensus that ADPG is made in the chloroplasts by ADPG pyrophosphorylase has been challenged by a controversial proposal that ADPG is made primarily in the cytosol, probably by sucrose synthase (SUS), and then imported into the chloroplasts. To resolve this long-standing controversy, we critically re-examined the experimental evidence that appears to conflict with the consensus pathway. We show that when precautions are taken to avoid artefactual changes during leaf sampling, Arabidopsis thaliana mutants that lack SUS activity in mesophyll cells (quadruple sus1234) or have no SUS activity (sextuple sus123456) have wild-type levels of ADPG and starch, while ADPG is 20 times lower in the pgm and adg1 mutants that are blocked in the classical pathway of starch synthesis. We conclude that the ADPG needed for starch synthesis in leaves is synthesized primarily by ADPG pyrophosphorylase in the chloroplasts.Significance statementMutant analysis shows that sucrose synthase makes no significant contribution to transitory starch synthesis in Arabidopsis leaves, resolving a 20-year old controversy about one of the most important pathways of photosynthetic metabolism.

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.

Ultrastructural observations on guard cells of Vicia faba and Allium porrum

1972 ◽  
Vol 50 (6) ◽  
pp. 1405-1413 ◽  
Author(s):  
W. G. Allaway ◽  
George Setterfield
Keyword(s):  
Vicia Faba ◽  
Small Groups ◽  
Guard Cell ◽  
Cell Walls ◽  
Guard Cells ◽  
Cell Physiology ◽  
Allium Porrum ◽  
Starch Granules ◽  
Mesophyll Cells ◽  
Guard Cell Chloroplasts

Stomata of Vicia faba and Allium porrum were examined in thin section with the electron microscope. Guard cells contained numerous mitochondria, few plastids, and relatively small vacuoles traversed by many strands of cytoplasm. Spherosomes were often observed but were variable in occurrence. Endoplasmic reticulum and dictyosomes were present, although not well developed. Scattered microtubules were present at the periphery of the cells. Microbodies were very rarely observed in guard cells and no plasmodesmata were ever seen in the guard cell walls. Plastids were small and irregular in outline in guard cells of both species. Guard cell plastids of V. faba contained abundant large starch granules. In both species thylakoids were few and grana were small in comparison with mesophyll plastids. The inner of the two bounding membranes of guard cell chloroplasts was extensively invaginated, forming a peripheral reticulum. This was not observed in mesophyll plastids of these species. Small groups of microtubule-like structures were often observed in V. faba guard cell plastids; microtubule-like structures were less frequent in A. porrum plastids, and were not in groups. The structures described are compared with those of other epidermal cells and mesophyll cells, and are discussed in relation to guard cell physiology.

Lipoxygenase 2 functions in exogenous nitric oxide-induced stomatal closure in Arabidopsis thaliana

2015 ◽  
Vol 42 (11) ◽  
pp. 1019 ◽  
Author(s):  
Yanfeng Sun ◽  
Dong Lv ◽  
Wei Wang ◽  
Wei Xu ◽  
Li Wang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Arabidopsis Thaliana ◽  
Potassium Channels ◽  
Stomatal Closure ◽  
Normal Growth ◽  
Guard Cells ◽  
Growth Conditions ◽  
Mesophyll Cells ◽  
No Donor ◽  
Leaf Water Loss

Nitric oxide (NO) and lipoxygenase (LOX)-derived oxylipins play important roles in stomatal closure in plants, and LOX–NO crosstalk has been indicated in mesophyll cells. However, whether the crosstalk also exists in guard cells is not clear and the detailed mechanisms remain unknown. Here, we report that exogenous sodium nitroprusside (SNP, a NO donor)-induced stomatal closure was clearly impaired in the AtLOX2 null mutant lox2–1 compared with wild-type (WT) Arabidopsis thaliana (L.) Heynh. Patch clamp analysis showed that the SNP-suppressed activity of inward-rectifying potassium channels in lox2–1 guard cell protoplasts was reduced. Moreover, SNP promoted an increase in cytosolic Ca2+ concentration in guard cells of lox2–1 mutants was inhibited compared with the WT. These results suggest that AtLOX2 plays an important role in NO-induced stomatal closure by affecting the cytosolic Ca2+ concentration increase and the activity of inward-rectifying potassium channels in guard cells. Furthermore, lox2–1 mutants showed a higher rate of leaf water loss and a relatively wider stomatal aperture than the WT under normal growth conditions. These data imply that AtLOX2 might modulate stomatal movement by increasing oxylipin generation in A. thaliana.

scholarly journals The Effect of Sonication on Plant Stomatal Movement

2020 ◽  
Vol 22 ◽  
Author(s):  
Suren Jeevaratnam ◽  
Chuwei Lin ◽  
Sixue Chen
Keyword(s):  
Arabidopsis Thaliana ◽  
Guard Cell ◽  
Guard Cells ◽  
Neutral Red ◽  
Time Interval ◽  
Stomatal Movement ◽  
Mesophyll Cells ◽  
Cell Purification ◽  
Cell Enrichment ◽  
A Minor

The primary goal of this study was to determine the effect of sonication on stomatal movement. A minor goal was to determine the best time interval at which sonication is the most effective at removing mesophyll cells and enriching guard cells. For this study, abaxial leaf peels of Arabidopsis thaliana were sonicated for 1, 3, 5, and 7-minute intervals at a set amplitude to analyze the removal of mesophyll cells. To juxtapose the leaves and to determine guard cell enrichment, microscopic images were taken prior to and after sonication. Furthermore, to establish that the stomata are alive, neutral red staining was used in conjunct with 40x magnification. It was hypothesized that sonication is an effective method for the removal of mesophyll cells and the enrichment of guard cells. The results of this study suggest that sonication is in fact an effective protocol for guard cell enrichment; however, it is not as effective for guard cell purification. This is due to the presence of mesophyll cells and epidermal layers present after sonication. Previous research dealing with sonication is very prevalent; however, research on sonication dealing with the removal of mesophyll cells in Arabidopsis thaliana is not widely studied. Thus, previous information to support this study could not be attained. Results from the first part of the experiment were then extended to determine how sonication affects stomatal movement. It was determined that in the experimental group, the average stomatal aperture decreased over a two-hour period.

scholarly journals Thiophene Derivatives as Anticancer Agents and Their Delivery to Tumor Cells Using Albumin Nanoparticles

Molecules ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 192 ◽  
Author(s):  
Guangsheng Cai ◽  
Simiao Wang ◽  
Lang Zhao ◽  
Yating Sun ◽  
Dongsheng Yang ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Cell Lines ◽  
Anticancer Agents ◽  
Drug Loading ◽  
Great Promise ◽  
Self Assembling ◽  
Laser Confocal Scanning Microscopy ◽  
Confocal Scanning ◽  
Thiophene Derivatives

A series of thiophene derivatives (TPs) were synthesized and evaluated for cytotoxicity in HepG2 and SMMC-7721 cell lines by MTT assay. TP 5 was identified as a potential anticancer agent based on its ability to inhibit tumor cell growth. Drawbacks of TPs, including poor solubility and high toxicity, were overcome through delivery using self-assembling HSA nanoparticles (NPs). The optimum conditions for TP 5-NPs synthesis obtained by adjusting the temperature and concentration of TP 5. The NPs had an encapsulation efficiency of 99.59% and drug-loading capacity of 3.70%. TP 5 was slowly released from TP 5-NPs in vitro over 120 h. HepG2 and SMMC-7721 cell lines were employed to study cytotoxicity of TP 5-NPs, which exhibited high potency. ROS levels were elevated and mitochondrial membrane potentials reversed when the two cell lines were treated with TP 5-NPs for 12 h. Cellular uptake of fluorescence-labeled TP 5-NPs in vitro was analyzed by flow cytometry and laser confocal scanning microscopy. Fluorescence intensity increased over time, suggesting that TP 5-NPs were efficiently taken up by tumor cells. In conclusion, TP 5-NPs showed great promise as an anticancer therapeutic agent.

scholarly journals A carbohydrate-binding protein, B-GRANULE CONTENT 1, influences starch granule size distribution in a dose-dependent manner in polyploid wheat

2019 ◽  
Vol 71 (1) ◽  
pp. 105-115 ◽  
Author(s):  
Tansy Chia ◽  
Marcella Chirico ◽  
Rob King ◽  
Ricardo Ramirez-Gonzalez ◽  
Benedetta Saccomanno ◽  
...  
Keyword(s):  
Size Distribution ◽  
Starch Granule ◽  
Starch Synthesis ◽  
Granule Size ◽  
Starch Granules ◽  
Grain Development ◽  
Polyploid Wheat ◽  
Gene Dose ◽  
Dose Dependent ◽  
B Granules

Abstract In Triticeae endosperm (e.g. wheat and barley), starch granules have a bimodal size distribution (with A- and B-type granules) whereas in other grasses the endosperm contains starch granules with a unimodal size distribution. Here, we identify the gene, BGC1 (B-GRANULE CONTENT 1), responsible for B-type starch granule content in Aegilops and wheat. Orthologues of this gene are known to influence starch synthesis in diploids such as rice, Arabidopsis, and barley. However, using polyploid Triticeae species, we uncovered a more complex biological role for BGC1 in starch granule initiation: BGC1 represses the initiation of A-granules in early grain development but promotes the initiation of B-granules in mid grain development. We provide evidence that the influence of BGC1 on starch synthesis is dose dependent and show that three very different starch phenotypes are conditioned by the gene dose of BGC1 in polyploid wheat: normal bimodal starch granule morphology; A-granules with few or no B-granules; or polymorphous starch with few normal A- or B-granules. We conclude from this work that BGC1 participates in controlling B-type starch granule initiation in Triticeae endosperm and that its precise effect on granule size and number varies with gene dose and stage of development.

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