Genetic elimination of a starch granule protein, SGP-1, of wheat generates an altered starch with apparent high amylose

A starch granule protein, SGP-1, is a starch synthase bound to starch granules in wheat endosperm. A wheat lacking SGP-1 was produced by crossing three variants each deficient in one of three SGP-1 classes, namely SGP-A1, -B1 or -D1. This deficient wheat (SGP-1 null wheat) showed some alterations in...

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Bibliographic Details
Published in:Theoretical and applied genetics 2000-07, Vol.101 (1-2), p.21-29
Main Authors: YAMAMORI, M, FUJITA, S, HAYAKAWA, K, MATSUKI, J, YASUI, T
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Amino acids
Amylopectin
amylose
Analysis
Biological and medical sciences
Chromatography
Enzymes
Fundamental and applied biological sciences. Psychology
Generalities. Genetics. Plant material
Genetic aspects
Genetic resources, diversity
Genetics and breeding of economic plants
Glucose
Glycerol
Plant genetics
Plant material
Protein research
Proteins
Scanning electron microscopy
Seeds
SGP-1 protein
Sperm
Triticum
Wheat
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Summary:A starch granule protein, SGP-1, is a starch synthase bound to starch granules in wheat endosperm. A wheat lacking SGP-1 was produced by crossing three variants each deficient in one of three SGP-1 classes, namely SGP-A1, -B1 or -D1. This deficient wheat (SGP-1 null wheat) showed some alterations in endosperm starch, meaning that SGP-1 is involved in starch synthesis. Electrophoretic experiments revealed that the levels of two starch granule proteins, SGP-2 and -3, decreased considerably in the SGP-1 null wheat though that of the waxy protein (granule-bound starch synthase I) did not. The A-type starch granules were deformed. Apparent high amylose level (30.8-37.4%) was indicated by colorimetric measurement, amperometric titration, and the concanavalin A method. The altered structure of amylopectin was detected by both high-performance size-exclusion chromatography and high-performance anion exchange chromatography. Levels of amylopectin chains with degrees of polymerization (DP) 6-10 increased, while DP 11-25 chains decreased. A low starch crystallinity was shown by both X-ray diffraction and differential scanning calorimetry (DSC) analyses because major peaks were absent. Abnormal crystallinity was also suggested by the lack of a polarized cross in SGP-1 null starch. The above results suggest that SGP-1 is responsible for amylopectin synthesis. Since the SGP-1 null wheat produced novel starch which has not been described before, it can be used to expand variation in wheat starch.
ISSN:0040-5752
1432-2242
DOI:10.1007/s001220051444