title: Engineering α-amylase levels in wheat grain suggests a highly sophisticated level of carbohydrate regulation during development.
abstract: Wheat starch degradation requires the synergistic action of different amylolytic enzymes. Our spatio-temporal study of wheat α-amylases throughout grain development shows that AMY3 is the most abundant isoform compared with the other known α-amylases. Endosperm-specific over-expression of AMY3 resulted in an increase of total α-amylase activity in harvested grains. Unexpectedly, increased activity did not have a significant impact on starch content or composition but led to an increase of soluble carbohydrate (mainly sucrose) in dry grain. In AMY3 overexpression lines (A3OE), germination was slightly delayed and triacylglycerol (TAG) content was increased in the endosperm of mature grain. Despite increased AMY3 transcript and protein content throughout grain development, alterations of α-amylase activity and starch granule degradation were not detected until grain maturation, suggesting a post-translational inhibition of α-amylase activity in the endosperm during the starch filling period. These findings show unexpected effects of a high level of α-amylase on grain development and composition, notably in carbon partitioning and TAG accumulation, and suggest the presence of a hitherto unknown regulatory pathway during grain filling.
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia.
authors: Alex
authors: A
authors: Whan
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia. Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
authors: Anne-Sophie
authors: AS
authors: Dielen
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia.
authors: Jos
authors: J
authors: Mieog
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia. Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
authors: Andrew F
authors: AF
authors: Bowerman
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia. Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
authors: Hannah M
authors: HM
authors: Robinson
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia. CSIRO Animal, Food and Health Sciences, St Lucia, Queensland, Australia.
authors: Keren
authors: K
authors: Byrne
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia. CSIRO Animal, Food and Health Sciences, St Lucia, Queensland, Australia.
authors: Michelle
authors: M
authors: Colgrave
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia. CSIRO Plant Industry, GPO Box 1600, Canberra ACT 2601 Australia.
authors: Philip J
authors: PJ
authors: Larkin
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia.
authors: Crispin A
authors: CA
authors: Howitt
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia.
authors: Matthew K
authors: MK
authors: Morell
authors: CSIRO Food Futures National Research Flagship, GPO Box 1600, Canberra ACT 2601 Australia. Jean.ral@csiro.au.
authors: Jean-Philippe
authors: JP
authors: Ral
mesh_terms: D050260:Carbohydrate Metabolism / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism; D014908:Triticum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014280:Triglycerides; D000516:alpha-Amylases
keywords: AMY3; endosperm.; oil; starch; sucrose; wheat