Structural features of α-glucans in the very early developαmental stage of rice endosperm. (September 2019)

• Record Type: Journal Article
• Authors: Nakamura, Yasunori; Ono, Masami; Ozaki, Noriaki
• Is Part Of: Journal of cereal science. Volume 89(2019)
• Publication Date: 2019-09
• Subjects: Amylopectin -- Initiation -- Rice endosperm -- Starch granules -- Starch biosynthesis; APTS 8-amino-1, 3, 6-pyrenesulfonic acid -- BDX branched dextrin -- BE starch branching enzyme -- BGI branched glucan intermediate -- DAP days after pollination -- DBE starch debranching enzyme -- DP degree of polymerization -- FACE fluorophore-assisted carbohydrate electrophoresis -- Փ-LD phosphorylase limit dextrin -- GBSS granule-bound starch synthase -- ISA isoamylase -- MDX maltodextrin -- MOS malto-oligosaccharide -- PaISA Pseudomonas amyloderamosa isoamylase -- Pho1 plastidial phosphorylase -- SEM scanning electron microscopy -- SS starch synthase; Grain -- Periodicals; Cereal products -- Periodicals; Céréales -- Périodiques; Produits céréaliers -- Périodiques; Cereal products; Grain; Periodicals; 664.705
• DOI: 10.1016/j.jcs.2019.05.012
• Languages: English
• ISSNs: 0733-5210

Abstract

Abstract: Up to now, no information on the structural characteristics of glucans involved in the initiation of starch biosynthesis in cereal endosperm has been available. Since amylopectin is a major constituent of starch and largely affects the starch physicochemical properties, we attempted to characterize the fine structures of branched glucans. We isolated small glucan granules with a diameter of approximately 40–80 nm from rice endosperm at the early developmental stages and analyzed the chain-length distribution of the glucans and their phosphorylase-limit dextrins. Compared with normal amylopectin, the proportion of long chains of these glucans with degree of polymerization (DP) ≥ 35 was significantly lower and these long chains did not form a peak. These structural features were commonly found in small glucan granules in three rice cultivars. Based on the present results, we propose that these immature glucans located in small granules in young endosperm are involved in the initiation process of amylopectin biosynthesis in rice endosperm. Highlights: Isolation and characterization of immature glucans in very young rice endosperm. The glucans having structurally an immature cluster compared with amylopectin. Possible role of immature glucans in the initial starch synthesis in rice endosperm. New insights into the specific initial stage of starch synthesis in cereal endosperm.