Abstract
BackgroundBy definition, amyloplasts are plastids specialized for starch production. However, a proteomic study of amyloplasts isolated from wheat (Triticum aestivum Butte 86) endosperm at 10 days after anthesis (DPA) detected enzymes from many other metabolic and biosynthetic pathways. To better understand the role of amyloplasts in food production, the data from that study were evaluated in detail and an amyloplast metabolic map was outlined.ResultsAnalysis of 288 proteins detected in an amyloplast preparation predicted that 178 were amyloplast proteins. Criteria included homology with known plastid proteins, prediction of a plastid transit peptide for the wheat gene product or a close homolog, known plastid location of the pathway, and predicted plastid location for other members of the same pathway. Of these, 135 enzymes were arranged into 18 pathways for carbohydrate, lipid, amino acid, nucleic acid and other biosynthetic processes that are critical for grain-fill. Functions of the other proteins are also discussed.ConclusionThe pathways outlined in this paper suggest that amyloplasts play a central role in endosperm metabolism. The interacting effects of genetics and environment on starch and protein production may be mediated in part by regulatory mechanisms within this organelle.
Highlights
IntroductionAmyloplasts are plastids specialized for starch production. a proteomic study of amyloplasts isolated from wheat (Triticum aestivum Butte 86) endosperm at 10 days after anthesis (DPA) detected enzymes from many other metabolic and biosynthetic pathways
By definition, amyloplasts are plastids specialized for starch production
There is an undesirable trade-off between yield and protein content that is determined by genetics and environment [1,2,3,4,5]
Summary
Amyloplasts are plastids specialized for starch production. a proteomic study of amyloplasts isolated from wheat (Triticum aestivum Butte 86) endosperm at 10 days after anthesis (DPA) detected enzymes from many other metabolic and biosynthetic pathways. To better understand the role of amyloplasts in food production, the data from that study were evaluated in detail and an amyloplast metabolic map was outlined. Desirable grain-fill traits for bread wheat include high rates of starch production for yield, and high protein content for breadmaking. There is an undesirable trade-off between yield and protein content that is determined by genetics and environment [1,2,3,4,5]. A better understanding of the role of the amyloplast in endosperm metabolism may help to understand and ameliorate this trade-off [6]. Prior to the grain-fill stage, yield is increased by increasing the number of tillers, heads and kernels through genetics, fertilization and water supply. Breeding for increased grain yield tends to increase starch more than protein, resulting in flour with a lower (page number not for citation purposes)
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