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 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.

Muhammad Nejatullah Siddiqui. Issues in Islamic Banking: Selected Papers, Leicester: The Islamic Foundation. 1983 , I 52pp.Author and Subject Indexes.

1983 ◽  
Vol 22 (1) ◽  
pp. 57-61
Author(s):  
Shahrukh Rafi Khan
Keyword(s):  
Analytical Model ◽  
Significant Contribution ◽  
Profit Sharing ◽  
Islamic Banking ◽  
Current State ◽  
The Subject ◽  
Made In

The book under review is a compilation of the author's articles and lectures that highlight the prominent developments in the literature on the subject of Islamic banking and inform the reader of the current state of debate on it. One of the earliest and main contributors to this topic is the author himself. The focus of this review will mainly be on "Economics of Profit-Sharing", which is the title of the fourth chapter of the book and is among his latest contributions. This chapter is a significant contribution as it is the first attempt to formalise the concept of profit sharing into an analytical model and, therefore, demands closer scrutiny. However, in the remaining chapters of the book, the author has drawn attention to some of the fine points made in the literature on this topic. Since some of these points appear to be controversial to me, I will briefly discuss them before moving on to the analytical chapter of the book.

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.

‘Yield to the mighty mind of the Popular Instructor’: Print and the Press in Martin Chuzzlewit

2020 ◽  
pp. 137-179
Author(s):  
Iain Crawford
Keyword(s):  
Mass Culture ◽  
Significant Contribution ◽  
The Novel ◽  
Negative Experience ◽  
Mass Market ◽  
The Press ◽  
Martin Chuzzlewit ◽  
First Time ◽  
The Relationship ◽  
Made In

Building on the case made in chapter 3, chapter 4 tunes to consider Martin Chuzzlewit and examines the ways in which the novel addresses the relationship between literacy, print media, and the experience of modern urbanism. Together eith its predecessor, the chapter argues that for Dickens America was far more than what has been generally perceived as an increasingly negative experience that chastened his understanding of the press and of mass culture. Rather, and notwithstanding all his complaints about Americans, tobacco, and spit, the encounter with America in fact provided him with a new sense, at once disturbing and alluring, of the potential power of a cheap mass-market press led by entrepreneurial editors operating in a print environment unconstrained by state controls. Moreover, in writing about America, and above all in writing about its newspapers in both American Notes and Martin Chuzzlewit, Dickens for the first time discovered a methodology for fusing fiction and the press in ways that would be foundational his most significant contribution to Victorian journalism, Household Words and its successor, All the Year Round.

Molecular Cloning and Spatial Expression of an ApL1 cDNA for the Large Subunit of ADP-Glucose Pyrophosphorylase from Arabidopsis thaliana

1999 ◽  
Vol 54 (5-6) ◽  
pp. 353-358 ◽  
Author(s):  
Leszek A. Kleszkowski ◽  
Lubomir N. Sokolov ◽  
Cheng Luo ◽  
Per Villand
Keyword(s):  
Arabidopsis Thaliana ◽  
Large Subunit ◽  
Critical Role ◽  
Starch Synthesis ◽  
Transit Peptide ◽  
Homologous Proteins ◽  
Peptide Cleavage ◽  
Reading Frame ◽  
Calculated Molecular Weight ◽  
Adp Glucose Pyrophosphorylase

Abstract A cDNA, A p L 1a , corresponding to a homologue of the large subunit of ADP-glucose pyrophosphorylase (AG Pase), has been isolated/characterised by screening a cDNA library prepared from leaves of Arabidopsis thaliana, followed by rapid amplification of cDNA 3′-ends (3′-RACE). Within the 1685 nucleotide-long sequence (excluding polyA tail), an open reading frame encodes a protein of 522 amino acids (aa), with a calculated molecular weight of 57.7 kDa. The derived aa sequence does not contain any discernible transit peptide cleavage site motif, similarly to two other recently sequenced full-length Arabidopsis homo-logues for AGPase, and shows ca. 58–78 % identity to homologous proteins from other plants/tissues. The corresponding gene was found (rosette and stem leaves, stems, flowers and fruits), consistent with its critical role in starch synthesis in

Non-host resistance responses of Arabidopsis thaliana to the coffee leaf rust fungus (Hemileia vastatrix)

Botany ◽  
2010 ◽  
Vol 88 (7) ◽  
pp. 621-629 ◽  
Author(s):  
Helena Gil Azinheira ◽  
Maria do Céu Silva ◽  
Pedro Talhinhas ◽  
Clara Medeira ◽  
Isabel Maia ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Leaf Rust ◽  
Rust Fungus ◽  
Hemileia Vastatrix ◽  
Callose Deposition ◽  
Mesophyll Cells ◽  
Model Plant ◽  
Heterologous System ◽  
Coffee Leaf Rust ◽  
Model Plant Arabidopsis Thaliana

Leaf rust, caused by Hemileia vastatrix Berk & Broome, is the most destructive fungal disease of coffee. In the absence of a suitable gene validation system in coffee, the objective of this study was to investigate whether the model plant Arabidopsis thaliana (L.) Heynh. may be used as a heterologous system for the molecular dissection of coffee responses to leaf rust. Histological examination of A. thaliana (Col-0) leaves inoculated with H. vastatrix (race II) showed that by 24 h after inoculation (hai), H. vastatrix uredospores differentiated appressoria and penetrated the stomata, but failed to form haustoria. Arabidopsis thaliana cellular resistance responses included hypersensitive-like response (HR) of stomata guard cells together with accumulation of phenolic compounds and callose deposition in walls of epidermal and mesophyll cells. Results indicate that H. vastatrix infection triggered the induction of a set of defence-related genes peaking at 18 and 42 hai. The non-host HR triggered by H. vastatrix in the model plant A. thaliana makes it usable to infer the function of coffee genes involved in pre-haustorial rust resistance.

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