Impact of down-regulation of starch branching enzyme IIb in rice by artificial microRNA- and hairpin RNA-mediated RNA silencing

Butardo, Vito M., Fitzgerald, Melissa A., Bird, Anthony R., Gidley, Michael J., Flanagan, Bernadine M., Larroque, Oscar, Resurreccion, Adoracion P., Laidlaw, Hunter K. C., Jobling, Stephen A., Morell, Matthew K. and Rahman, Sadequr (2011) Impact of down-regulation of starch branching enzyme IIb in rice by artificial microRNA- and hairpin RNA-mediated RNA silencing. Journal of Experimental Botany, 62 14: 4927-4941. doi:10.1093/jxb/err188


Author Butardo, Vito M.
Fitzgerald, Melissa A.
Bird, Anthony R.
Gidley, Michael J.
Flanagan, Bernadine M.
Larroque, Oscar
Resurreccion, Adoracion P.
Laidlaw, Hunter K. C.
Jobling, Stephen A.
Morell, Matthew K.
Rahman, Sadequr
Title Impact of down-regulation of starch branching enzyme IIb in rice by artificial microRNA- and hairpin RNA-mediated RNA silencing
Journal name Journal of Experimental Botany   Check publisher's open access policy
ISSN 0022-0957
1460-2431
Publication date 2011-10
Sub-type Article (original research)
DOI 10.1093/jxb/err188
Volume 62
Issue 14
Start page 4927
End page 4941
Total pages 15
Place of publication Southampton, United Kingdom
Publisher Oxford University Press
Collection year 2012
Language eng
Formatted abstract
The inactivation of starch branching IIb (SBEIIb) in rice is traditionally associated with elevated apparent amylose content, increased peak gelatinization temperature, and a decreased proportion of short amylopectin branches. To elucidate further the structural and functional role of this enzyme, the phenotypic effects of down-regulating SBEIIb expression in rice endosperm were characterized by artificial microRNA (amiRNA) and hairpin RNA (hp-RNA) gene silencing. The results showed that RNA silencing of SBEIIb expression in rice grains did not affect the expression of other major isoforms of starch branching enzymes or starch synthases. Structural analyses of debranched starch showed that the doubling of apparent amylose content was not due to an increase in the relative proportion of amylose chains but instead was due to significantly elevated levels of long amylopectin and intermediate chains. Rices altered by the amiRNA technique produced a more extreme starch phenotype than those modified using the hp-RNA technique, with a greater increase in the proportion of long amylopectin and intermediate chains. The more pronounced starch structural modifications produced in the amiRNA lines led to more severe alterations in starch granule morphology and crystallinity as well as digestibility of freshly cooked grains. The potential role of attenuating SBEIIb expression in generating starch with elevated levels of resistant starch and lower glycaemic index is discussed.
Keyword CP
MAS NMR
Crystalline polymorph
RNA interference
Starch granules
XRD
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
Centre for Nutrition and Food Sciences Publications
 
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