Loss of starch synthase IIIa changes starch molecular structure and granule morphology in grains of hexaploid bread wheat.

A - Papers appearing in refereed journals

Fahy, B., Gonzalez, O., Savva, G. M., Ahn-Jarvis, J. H., Warren, F. J., Dunn, J., Lovegrove, A. and Hazard, B. A 2022. Loss of starch synthase IIIa changes starch molecular structure and granule morphology in grains of hexaploid bread wheat. Scientific Reports. 12, p. 10806. https://doi.org/10.1038/s41598-022-14995-0

AuthorsFahy, B., Gonzalez, O., Savva, G. M., Ahn-Jarvis, J. H., Warren, F. J., Dunn, J., Lovegrove, A. and Hazard, B. A
Abstract

Starch synthase III plays a key role in starch biosynthesis and is highly expressed in developing wheat grains. To understand the contribution of SSIII to starch and grain properties, we developed wheat ssIIIa mutants in the elite cultivar Cadenza using in silico TILLING in a mutagenized population. SSIIIa protein was undetectable by immunoblot analysis in triple ssIIIa mutants carrying mutations in each homoeologous copy of ssIIIa (A, B and D). Loss of SSIIIa in triple mutants led to significant changes in starch phenotype including smaller A-type granules and altered granule morphology. Starch chain-length distributions of double and triple mutants indicated greater levels of amylose than sibling controls (33.8% of starch in triple mutants, and 29.3% in double mutants vs. 25.5% in sibling controls) and fewer long amylopectin chains. Wholemeal flour of triple mutants had more resistant starch (6.0% vs. 2.9% in sibling controls) and greater levels of non-starch polysaccharides; the grains appeared shrunken and weighed ~ 11% less than the sibling control which was partially explained by loss in starch content. Interestingly, our study revealed gene dosage effects which could be useful for fine-tuning starch properties in wheat breeding applications while minimizing impact on grain weight and quality.

Year of Publication2022
JournalScientific Reports
Journal citation12, p. 10806
Digital Object Identifier (DOI)https://doi.org/10.1038/s41598-022-14995-0
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDFW - Designing Future Wheat - Work package 2 (WP2) - Added value and resilience
Publisher's version
Output statusPublished
Publication dates
Online25 Jun 2022
Publication process dates
Accepted16 Jun 2022
PublisherNature Publishing Group
ISSN2045-2322

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