Abstract
Main conclusion
Linear glucans with degree of polymerization of up to 23 were detected in rice endosperm at the very early developmental stage of endosperm and considered to play an important role in the de novo synthesis of branched glucans.
Abstract
Little is known concerning the contribution of malto-oligosaccharides (MOS) and longer linear glucans to the starch biosynthesis in cereal endosperm. In the present study, the changes in the amount of major metabolic intermediates including MOS and linear glucans with a degree of polymerization (DP) of ≤ 9 and ≥ 10, respectively, in rice endosperm were measured during the development. Significant amounts of linear glucans of at least DP23 were present in the endosperm at 3 and 5 days after pollination (DAP), whereas most MOS of DP up to 8 were detected in the endosperm throughout the development up to 20 DAP. It was also found that a significant amount of simple sugars such as sucrose, glucose, and fructose, and organic acids such as malic acid, citric acid, and succinic acid were present in the developing endosperm. Although the levels of metabolites are not directly related to the extent of the metabolic flux, the present results suggest that MOS and linear glucans as well as these sugars and organic acids are involved in starch biosynthesis of rice endosperm. It is thought that linear glucans might play a role in starch biosynthesis in rice endosperm, presumably as the precursor for the subsequent synthesis of branched glucans involved in the initiation process that is possibly active in the endosperm at the very early developmental stage.
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Abbreviations
- APTS:
-
8-Amino-1,3,6-pyrenesulfonic acid
- BE:
-
Starch branching enzyme
- DAP:
-
Days after pollination
- DBE:
-
Starch debranching enzyme
- DP:
-
Degree of polymerization
- DPE:
-
Disproportionating enzyme
- ELSD:
-
Evaporative light scattering detector
- FACE:
-
Fluorophore-assisted carbohydrate electrophoresis
- GBSS:
-
Granule-bound starch synthase
- LOD:
-
Limit of detection
- LOQ:
-
Limit of quantification
- MOS:
-
Malto-oligosaccharide
- Pho1:
-
Plastidial phosphorylase
- SS:
-
Starch synthase
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We thank Dr. Fujita for her help to use facilities of Akita Prefectural University.
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Communicated by Anastasios Melis.
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Nakamura, Y., Ono, M., Suto, M. et al. Analysis of malto-oligosaccharides and related metabolites in rice endosperm during development. Planta 251, 110 (2020). https://doi.org/10.1007/s00425-020-03401-6
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DOI: https://doi.org/10.1007/s00425-020-03401-6