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Barley grains, deficient in cytosolic small subunit of ADP-glucose pyrophosphorylase, reveal coordinate adjustment of C:N metabolism mediated by an overlapping metabolic-hormonal control.
- Source :
-
The Plant journal : for cell and molecular biology [Plant J] 2012 Mar; Vol. 69 (6), pp. 1077-93. Date of Electronic Publication: 2012 Jan 10. - Publication Year :
- 2012
-
Abstract
- The barley Risø16 mutation leads to inactivation of cytosolic ADP-Glc pyrophosphorylase, and results in decreased ADP-Glc and endospermal starch levels. Here we show that this mutation is accompanied by a decrease in storage protein accumulation and seed size, which indicates that alteration of a single enzymatic step can change the network of storage metabolism as a whole. We used comprehensive transcript, metabolite and hormonal profiling to compare grain metabolism and development of Risø16 and wild-type endosperm. Despite increased sugar availability in mutant endosperm, glycolytic intermediates downstream of hexose phosphates remained unchanged or decreased, while several glycolytic enzymes were downregulated at the transcriptional level. Metabolite and transcript profiling also indicated an inhibition of the tricarboxylic acid cycle at the level of mitochondrial nicotinamide adenine dinucleotide (NAD)-isocitrate dehydrogenase and an attendant decrease in alpha-ketoglutarate and amino acids levels in Risø16, compared with wild type. Decreased levels of cytokinins in Risø16 endosperm suggested co-regulation between starch synthesis, abscisic acid (ABA) deficiency and cytokinin biosynthesis. Comparative cis-element analysis in promoters of jointly downregulated genes in Risø16 revealed an overlap between metabolic and hormonal regulation, which leds to a coordinated downregulation of endosperm-specific and ABA-inducible gene expression (storage proteins) together with repression by sugars (isocitrate dehydrogenase, amylases). Such co-regulation ensured that decreased carbon fluxes into starch lead to a coordinated inhibition of glycolysis, amino acid and storage proteins biosynthesis, which is useful in the prevention of osmotic imbalances and oxidative stress due to increased accumulation of sugars.<br /> (© 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.)
- Subjects :
- Abscisic Acid biosynthesis
Amino Acids metabolism
Amylases genetics
Amylases metabolism
Citric Acid Cycle
Cytokinins biosynthesis
Endosperm genetics
Endosperm metabolism
Endosperm physiology
Gene Expression Regulation, Plant
Glucose-1-Phosphate Adenylyltransferase genetics
Glycolysis
Hordeum genetics
Hordeum metabolism
Hordeum physiology
Isocitrate Dehydrogenase genetics
Isocitrate Dehydrogenase metabolism
Mitochondria enzymology
Mitochondria genetics
Mitochondria metabolism
Mutation
Plant Growth Regulators genetics
Plant Proteins genetics
Plant Proteins metabolism
Promoter Regions, Genetic
Seed Storage Proteins genetics
Seed Storage Proteins metabolism
Starch biosynthesis
Carbon metabolism
Cytosol metabolism
Glucose-1-Phosphate Adenylyltransferase metabolism
Hordeum enzymology
Nitrogen metabolism
Plant Growth Regulators metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1365-313X
- Volume :
- 69
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- The Plant journal : for cell and molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 22098161
- Full Text :
- https://doi.org/10.1111/j.1365-313X.2011.04857.x