Dataset Information

Competition between Granule Bound Starch Synthase and Starch Branching Enzyme in Starch Biosynthesis.

ABSTRACT:

Background

Starch branching enzymes (SBE) and granule-bound starch synthase (GBSS) are two important enzymes for starch biosynthesis. SBE mainly contributes to the formation of side branches, and GBSS mainly contributes for the synthesis of amylose molecules. However, there are still gaps in the understanding of possible interactions between SBE and GBSS.

Results

Nineteen natural rice varieties with amylose contents up to 28% were used. The molecular structure, in the form of the chain-length distribution (CLDs, the distribution of the number of monomer units in each branch) was measured after enzymatic debranching, using fluorophore-assisted carbohydrate electrophoresis for amylopectin and size- exclusion chromatography for amylose. The resulting distributions were fitted to two mathematical models based on the underlying biosynthetic processes, which express the CLDs in terms of parameters reflecting relevant enzyme activities.

Conclusions

Finding statistically valid correlations between the values of these parameters showed that GBSSI and SBEI compete for substrates during rice starch biosynthesis, and synthesis of amylose short chains involves several enzymes including GBSSI, SBE and SSS (soluble starch synthase). Since the amylose CLD is important for a number of functional properties such as digestion rate, this knowledge is potentially useful for developing varieties with improved functional properties.

SUBMITTER: Han H

PROVIDER: S-EPMC6928174 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Publications

Competition between Granule Bound Starch Synthase and Starch Branching Enzyme in Starch Biosynthesis.

Han Huaxin H Yang Chuantian C Zhu Jihui J Zhang Lixia L Bai Yeming Y Li Enpeng E Gilbert Robert G RG

Rice (New York, N.Y.) 20191223 1

<h4>Background</h4>Starch branching enzymes (SBE) and granule-bound starch synthase (GBSS) are two important enzymes for starch biosynthesis. SBE mainly contributes to the formation of side branches, and GBSS mainly contributes for the synthesis of amylose molecules. However, there are still gaps in the understanding of possible interactions between SBE and GBSS.<h4>Results</h4>Nineteen natural rice varieties with amylose contents up to 28% were used. The molecular structure, in the form of the ...[more]

PMID: 31872316

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Project description:BackgroundPolyploidy and hybridization are ubiquitous in Rubus L., a large and taxonomically challenging genus. Chinese Rubus are mainly concentrated into two major sections, the diploid Idaeobatus and the polyploid Malachobatus. However, it remains unclear to be auto- or allo- polyploid origin of polyploids in Rubus. We investigated the homoeologs and the structure of the GBSSI-1 (granule-bound starch synthase I) gene in 140 Rubus individuals representing 102 taxa in 17 (out of the total 24) subsections of 7 (total of 12) sections at different ploidy levels.ResultsBased on the gene structure and sequence divergence, we defined three gene variants, GBSSI-1a, GBSSI-1b, and GBSSI-1c. When compared with GBSSI-1a, both GBSSI-1b and GBSSI-1c have a shorter fourth intron, and GBSSI-1c had an additional deletion in the fifth intron. For diploids, either GBSSI-1a or GBSSI-1b was detected in 56 taxa consisting of 82 individuals from sect. Idaeobatus, while both alleles existed in R. pentagonus and R. peltatus. Both homoeologs GBSSI-1a and GBSSI-1b were identified in 39 taxa (48 individuals) of Malachobatus polyploids. They were also observed in two sect. Dalibardastrum taxa, in one sect. Chamaebatus taxon, and in three taxa from sect. Cylactis. Interestingly, all three homoeologs were observed in the three tetraploid taxa. Phylogenetic trees and networks suggested two clades (I and II), corresponding to GBSSI-1a, and GBSSI-1b/1c sequences, respectively. GBSSI-1 homoeologs from the same polyploid individual were resolved in different well-supported clades, and some of these homoelogs were more closely related to homoelogs in other species than they were to each other. This implied that the homoeologs of these polyploids were donated by different ancestral taxa, indicating their allopolyploid origin. Two kinds of diploids hybridized to form most allotetraploid species. The early-divergent diploid species with GBSSI-1a or -1b emerged before polyploid formation in the evolutionary history of Rubus.ConclusionThis study provided new insights into allopolyploid origin and evolution from diploid to polyploid within the genus Rubus at the molecular phylogenetic level, consistent with the taxonomic treatment by Yü et al. and Lu.

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Dataset Information

Competition between Granule Bound Starch Synthase and Starch Branching Enzyme in Starch Biosynthesis.

Background

Results

Conclusions

Publications

Competition between Granule Bound Starch Synthase and Starch Branching Enzyme in Starch Biosynthesis.

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