title: The evolution of the starch biosynthetic pathway in cereals and other grasses.
abstract: In most species, the precursor for starch synthesis, ADPglucose, is made exclusively in the plastids by the enzyme ADPglucose pyrophosphorylase (AGPase). However, in the endosperm of grasses, including the economically important cereals, ADPglucose is also made in the cytosol via a cytosolic form of AGPase. Cytosolic ADPglucose is imported into plastids for starch synthesis via an ADPglucose/ADP antiporter (ADPglucose transporter) in the plastid envelope. The genes encoding the two subunits of cytosolic AGPase and the ADPglucose transporter are unique to grasses. In this review, the evolutionary origins of this unique endosperm pathway of ADPglucose synthesis and its functional significance are discussed. It is proposed that the genes encoding the pathway originated from a whole-genome-duplication event in an early ancestor of the grasses.
authors.affiliation: John Innes Centre, Norwich Research Park, Colney, Norwich, Norfolk NR4 7UH, UK.
authors.forename: Sylviane
authors.initials: S
authors.lastname: Comparot-Moss
authors.forename: Kay
authors.initials: K
authors.lastname: Denyer
mesh_terms: D005075:Biological Evolution; D053898:Biosynthetic Pathways; D002523:Edible Grain / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D006109:Poaceae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D013213:Starch / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D010940:Plant Proteins; D013213:Starch; D051599:Glucose-1-Phosphate Adenylyltransferase; D005947:Glucose