scholarly journals Enzymic capacities of amyloplasts from wheat (Triticum aestivum) endosperm

1988 ◽  
Vol 255 (2) ◽  
pp. 391-396 ◽  
Author(s):  
G Entwistle ◽  
T A Rees
Keyword(s):  
Triticum Aestivum ◽  
Significant Proportion ◽  
Starch Synthesis ◽  
Immunoblot Analysis ◽  
Glycolytic Enzyme ◽  
Starch Synthase ◽  
Wheat Endosperm ◽  
Fructose 1,6 Bisphosphatase ◽  
Enzyme Distribution ◽  
Adp Glucose Pyrophosphorylase

Lysates of protoplasts from the endosperm of developing grains of wheat (Triticum aestivum) were fractionated on density gradients of Nycodenz to give amyloplasts. Enzyme distribution on the gradients suggested that: (i) starch synthase and ADP-glucose pyrophosphorylase are confined to the amyloplasts; (ii) pyrophosphate: fructose-6-phosphate 1-phosphotransferase and UDP-glucose pyrophosphorylase are confined to the cytosol; (iii) a significant proportion (23-45%) of each glycolytic enzyme, from phosphoglucomutase to pyruvate kinase inclusive, is in the amyloplast. Starch synthase, ADP-glucose pyrophosphorylase and each of the glycolytic enzymes showed appreciable latency when assayed in unfractionated lysates of protoplasts. No activity of fructose-1,6-bisphosphatase was found in amyloplasts or in homogenates of endosperm. Antibody to plastidic fructose-1,6-bisphosphatase did not react positively, in an immunoblot analysis, with any protein in extracts of wheat endosperm. It is argued that wheat endosperm lacks significant plastidic fructose-1,6-bisphosphatase and that carbon for starch synthesis does not enter the amyloplast as a C-3 compound but probably as hexose phosphate.

Comprehensive analysis of the transcription of starch synthesis genes and the transcription factor RSR1 in wheat (Triticum aestivum) endosperm

Genome ◽  
2013 ◽  
Vol 56 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Guo-Zhang Kang ◽  
Wei Xu ◽  
Guo-Qin Liu ◽  
Xiao-Qi Peng ◽  
Tian-Cai Guo
Keyword(s):  
Triticum Aestivum ◽  
Transcription Factor ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Starch Synthesis ◽  
Grain Development ◽  
Wheat Endosperm ◽  
Group 2 ◽  
Endosperm Starch ◽  
Late Stages

The cDNA sequences of 26 starch synthesis genes were identified in common wheat (Triticum aestivum L.), and their transcript levels were measured using quantitative real-time RT–PCR to assess the function of individual genes and the regulatory mechanism in wheat endosperm. The expression patterns of 26 genes in wheat endosperm were classified into three groups. The genes in group 1 were richly expressed in the early stage of grain development and may be involved in the construction of fundamental cell machinery, synthesis of glucan primers, and initiation of starch granules. The genes in group 2 were highly expressed during the middle and late stages of grain development, and their expression profiles were similar to the accumulation rate of endosperm starch; these genes are presumed to play a crucial role in starch production. The genes in group 3 were scantily expressed throughout the grain development period and might be associated with transitory starch synthesis. Transcripts of the negative transcription factor TaRSR1 were high at the early and late stages of grain development but low during the middle stage. The expression pattern of TaRSR1 was almost opposite to those of the group 2 starch synthesis genes, indicating that TaRSR1 might negatively regulate the expression of many endosperm starch synthesis genes during grain development.

scholarly journals Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

2020 ◽  
Author(s):  
Adam Schoen ◽  
Anupama Joshi ◽  
Vijay K Tiwari ◽  
Bikram S. Gill ◽  
Nidhi Rawat
Keyword(s):  
Resistant Starch ◽  
Amylose Content ◽  
Starch Content ◽  
Wheat Variety ◽  
Starch Synthesis ◽  
Starch Synthase ◽  
Single Individual ◽  
Individual Genome ◽  
Mutant Genotype ◽  
Knock Out

Abstract Background: Lack of nutritionally appropriate foods is one of the leading causes of obesity in the US and worldwide. Wheat (Triticum aestivum) provides 20% of the calories consumed daily across the globe. The nutrients in the wheat grain come primarily from the starch composed of amylose and amylopectin. Resistant starch content, which is known to have significant human health benefits, can be increased by modifying starch synthesis pathways. Starch synthase enzyme SSIIa, also known as starch granule protein isoform-1 (SGP-1), is integral to the biosynthesis of the branched and readily digestible glucose polymer amylopectin. The goal of this work was to develop a triple null mutant genotype for SSIIa locus in the elite hard red winter wheat variety ‘Jagger’ and evaluate the effect of the knock-out mutations on resistant starch content in grains with respect to wild type. Results: Knock-out mutations in SSIIa in the three genomes of wheat variety ‘Jagger’ were identified using TILLING. Subsequently, these loss-of function mutations on A, B, and D genomes were combined by crossing to generate a triple knockout mutant genotype Jag-ssiia-∆ABD. The Jag-ssiia-∆ABD had an amylose content of 35.70% compared to 31.15% in Jagger, leading to ~118% increase in resistant starch in the Jag-ssiia-∆ABD genotype of Jagger wheat. The single individual genome mutations also had various effects on starch composition. Conclusions: Our full null Jag-ssiia-∆ABD mutant showed a significant increase in RS without the shriveled grain phenotype seen in other ssiia knockouts in elite wheat cultivars. Moreover, this study shows the potential for developing nutritionally improved foods in a non-GM approach. Since all the mutants have been developed in an elite wheat cultivar, their adoption in production and supply will be feasible in future.

scholarly journals Suppression of starch synthase I expression affects the granule morphology and granule size and fine structure of starch in wheat endosperm

2014 ◽  
Vol 65 (8) ◽  
pp. 2189-2201 ◽  
Author(s):  
S. J. McMaugh ◽  
J. L. Thistleton ◽  
E. Anschaw ◽  
J. Luo ◽  
C. Konik-Rose ◽  
...  
Keyword(s):  
Fine Structure ◽  
Granule Size ◽  
Starch Synthase ◽  
Wheat Endosperm ◽  
Granule Morphology

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

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