scholarly journals Starch Biosynthesis: Understanding the Functions and Interactions of Multiple Isozymes of Starch Synthase and Branching Enzyme.

1998 ◽  
Vol 10 (54) ◽  
pp. 307-319 ◽  
Author(s):  
H. P. Guan ◽  
P. L. Keeling
Keyword(s):  
Starch Biosynthesis ◽  
Starch Synthase ◽  
Branching Enzyme

scholarly journals Inactivation of rice starch branching enzyme IIb triggers broad and unexpected changes in metabolism by transcriptional reprogramming

2020 ◽  
Vol 117 (42) ◽  
pp. 26503-26512
Author(s):  
Can Baysal ◽  
Wenshu He ◽  
Margit Drapal ◽  
Gemma Villorbina ◽  
Vicente Medina ◽  
...  
Keyword(s):  
Amylose Content ◽  
Starch Biosynthesis ◽  
Starch Synthase ◽  
Rice Starch ◽  
Biosynthesis Pathway ◽  
Branching Enzyme ◽  
Starch Branching Enzyme ◽  
Rice Endosperm ◽  
Primary And Secondary Metabolites ◽  
Genes Encoding

Starch properties can be modified by mutating genes responsible for the synthesis of amylose and amylopectin in the endosperm. However, little is known about the effects of such targeted modifications on the overall starch biosynthesis pathway and broader metabolism. Here we investigated the effects of mutating theOsSBEIIbgene encoding starch branching enzyme IIb, which is required for amylopectin synthesis in the endosperm. As anticipated, homozygous mutant plants, in which OsSBEIIb was completely inactivated by abolishing the catalytic center and C-terminal regulatory domain, produced opaque seeds with depleted starch reserves. Amylose content in the mutant increased from 19.6 to 27.4% and resistant starch (RS) content increased from 0.2 to 17.2%. Many genes encoding isoforms of AGPase, soluble starch synthase, and other starch branching enzymes were up-regulated, either in their native tissues or in an ectopic manner, whereas genes encoding granule-bound starch synthase, debranching enzymes, pullulanase, and starch phosphorylases were largely down-regulated. There was a general increase in the accumulation of sugars, fatty acids, amino acids, and phytosterols in the mutant endosperm, suggesting that intermediates in the starch biosynthesis pathway increased flux through spillover pathways causing a profound impact on the accumulation of multiple primary and secondary metabolites. Our results provide insights into the broader implications of perturbing starch metabolism in rice endosperm and its impact on the whole plant, which will make it easier to predict the effect of metabolic engineering in cereals for nutritional improvement or the production of valuable metabolites.

scholarly journals Functional Analysis of Starch Metabolism in Plants

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1152 ◽  
Author(s):  
Yong-Gu Cho ◽  
Kwon-Kyoo Kang
Keyword(s):  
Transcription Factors ◽  
Starch Biosynthesis ◽  
Starch Synthase ◽  
Starch Metabolism ◽  
Branching Enzyme ◽  
Structural Genes ◽  
Starch Branching Enzyme ◽  
Fixed Carbon ◽  
Debranching Enzyme ◽  
Storage Organs

In plants, starch is synthesized in leaves during the day-time from fixed carbon through photosynthesis and is mobilized at night to support continued respiration, sucrose export, and growth in the dark. The main crops where starch is biosynthesized and stored are corn, rice, wheat, and potatoes, and they are mainly used as food resources for humankind. There are many genes that are involved in starch biosynthesis from cytosol to storage organs in plants. ADP-glucose, UDP- glucose, and glucose-6-phosphate are synthesized catalyzed by UDP-invertase, AGPase, hexokinase, and P- hexose-isomerase in cytosol. Starch composed of amylopectin and amylose is synthesized by starch synthase, granule bound starch synthase, starch-branching enzyme, debranching enzyme, and pullulanase, which is primarily responsible for starch production in storage organs. Recently, it has been uncovered that structural genes are controlled by proteins derived from other genes such as transcription factors. To obtain more precise information on starch metabolism, the functions of genes and transcription factors need to be studied to understand their roles and functions in starch biosynthesis in plants. However, the roles of genes related to starch biosynthesis are not yet clearly understood. The papers of this special issue contain reviews and research articles on these topics and will be a useful resource for researchers involved in the quality improvement of starch storage crops.

Multiple effects of the starch synthase II mutation in developing wheat endosperm

2007 ◽  
Vol 34 (5) ◽  
pp. 431 ◽  
Author(s):  
Behjat Kosar-Hashemi ◽  
Zhongyi Li ◽  
Oscar Larroque ◽  
Ahmed Regina ◽  
Makoto Yamamori ◽  
...  
Keyword(s):  
Triticum Aestivum L ◽  
Endosperm Development ◽  
Starch Synthase ◽  
Starch Granules ◽  
Branching Enzyme ◽  
Wild Type ◽  
Drastic Reduction ◽  
Branching Patterns ◽  
Soluble Phase ◽  
Mutant Lines

A line of wheat (Triticum aestivum L.), sgp-1, that does not express starch synthase II (SSII, also known as SGP-1) has previously been reported. In this study, F1 derived doubled haploid lines with homozygous wild type or mutant alleles for SGP-1 genes were identified from a cross between the original mutant and a wild type Australian cultivar. Analysis of the starch granules showed that in the mutant lines they are markedly distorted from 15 days postanthesis during grain development. Starch branching patterns showed an increase in the proportion of short chains (DP 6–10) at an earlier stage, but this increase became much more pronounced at 15 days postanthesis and persisted until maturity. There was also a consistent and drastic reduction throughout seed development in the relative amounts of starch branching enzyme II (SBEII, comprising SBEIIa and SBEIIb) and starch synthase I (SSI) bound to the starch granules. In the soluble phase, however, there was relatively little change in the amount of SBEIIb, SBEIIa or SSI protein. Therefore loss of SSII specifically leads to the loss of SBEIIb, SBEIIa and SSI protein in the granule-bound phase and the effect of this mutation is clearly manifest from the mid-stage of endosperm development in wheat.

scholarly journals Soluble isoforms of starch synthase and starch-branching enzyme also occur within starch granules in developing pea embryos

1993 ◽  
Vol 4 (1) ◽  
pp. 191-198 ◽  
Author(s):  
Kay Denyer ◽  
Christopher Sidebottom ◽  
Christopher M. Hylton ◽  
Alison M. Smith
Keyword(s):  
Starch Synthase ◽  
Starch Granules ◽  
Branching Enzyme ◽  
Starch Branching Enzyme
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