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Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm

The enzyme starch synthase IIa (SSIIa) in cereals has catalytic and regulatory roles during the synthesis of amylopectin that influences the functional properties of the grain. Rice endosperm SSIIa is more active in indica accessions compared to japonica lines due to functional SNP variations in the...

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Autores principales: Jr., Vito M. Butardo, Luo, Jixun, Li, Zhongyi, Gidley, Michael J., Bird, Anthony R., Tetlow, Ian J., Fitzgerald, Melissa, Jobling, Stephen A., Rahman, Sadequr
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142255/
https://www.ncbi.nlm.nih.gov/pubmed/32300357
http://dx.doi.org/10.3389/fgene.2020.00289
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author Jr., Vito M. Butardo
Luo, Jixun
Li, Zhongyi
Gidley, Michael J.
Bird, Anthony R.
Tetlow, Ian J.
Fitzgerald, Melissa
Jobling, Stephen A.
Rahman, Sadequr
author_facet Jr., Vito M. Butardo
Luo, Jixun
Li, Zhongyi
Gidley, Michael J.
Bird, Anthony R.
Tetlow, Ian J.
Fitzgerald, Melissa
Jobling, Stephen A.
Rahman, Sadequr
author_sort Jr., Vito M. Butardo
collection PubMed
description The enzyme starch synthase IIa (SSIIa) in cereals has catalytic and regulatory roles during the synthesis of amylopectin that influences the functional properties of the grain. Rice endosperm SSIIa is more active in indica accessions compared to japonica lines due to functional SNP variations in the coding region of the structural gene. In this study, downregulating the expression of japonica-type SSIIa in Nipponbare endosperm resulted in either shrunken or opaque grains with an elevated proportion of A-type starch granules. Shrunken seeds had severely reduced starch content and could not be maintained in succeeding generations. In comparison, the opaque grain morphology was the result of weaker down-regulation of SSIIa which led to an elevated proportion of short-chain amylopectin (DP 6-12) and a concomitant reduction in the proportion of medium-chain amylopectin (DP 13-36). The peak gelatinization temperature of starch and the estimated glycemic score of cooked grain as measured by the starch hydrolysis index were significantly reduced. These results highlight the important role of medium-chain amylopectin in influencing the functional properties of rice grains, including its digestibility. The structural, regulatory and nutritional implications of down-regulated japonica-type SSIIa in rice endosperm are discussed.
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spelling pubmed-71422552020-04-16 Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm Jr., Vito M. Butardo Luo, Jixun Li, Zhongyi Gidley, Michael J. Bird, Anthony R. Tetlow, Ian J. Fitzgerald, Melissa Jobling, Stephen A. Rahman, Sadequr Front Genet Genetics The enzyme starch synthase IIa (SSIIa) in cereals has catalytic and regulatory roles during the synthesis of amylopectin that influences the functional properties of the grain. Rice endosperm SSIIa is more active in indica accessions compared to japonica lines due to functional SNP variations in the coding region of the structural gene. In this study, downregulating the expression of japonica-type SSIIa in Nipponbare endosperm resulted in either shrunken or opaque grains with an elevated proportion of A-type starch granules. Shrunken seeds had severely reduced starch content and could not be maintained in succeeding generations. In comparison, the opaque grain morphology was the result of weaker down-regulation of SSIIa which led to an elevated proportion of short-chain amylopectin (DP 6-12) and a concomitant reduction in the proportion of medium-chain amylopectin (DP 13-36). The peak gelatinization temperature of starch and the estimated glycemic score of cooked grain as measured by the starch hydrolysis index were significantly reduced. These results highlight the important role of medium-chain amylopectin in influencing the functional properties of rice grains, including its digestibility. The structural, regulatory and nutritional implications of down-regulated japonica-type SSIIa in rice endosperm are discussed. Frontiers Media S.A. 2020-04-02 /pmc/articles/PMC7142255/ /pubmed/32300357 http://dx.doi.org/10.3389/fgene.2020.00289 Text en Copyright © 2020 Butardo, Luo, Li, Gidley, Bird, Tetlow, Fitzgerald, Jobling and Rahman. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Genetics
Jr., Vito M. Butardo
Luo, Jixun
Li, Zhongyi
Gidley, Michael J.
Bird, Anthony R.
Tetlow, Ian J.
Fitzgerald, Melissa
Jobling, Stephen A.
Rahman, Sadequr
Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm
title Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm
title_full Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm
title_fullStr Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm
title_full_unstemmed Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm
title_short Functional Genomic Validation of the Roles of Soluble Starch Synthase IIa in Japonica Rice Endosperm
title_sort functional genomic validation of the roles of soluble starch synthase iia in japonica rice endosperm
topic Genetics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142255/
https://www.ncbi.nlm.nih.gov/pubmed/32300357
http://dx.doi.org/10.3389/fgene.2020.00289
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