Journal article
Engineering starch biosynthesis for increasing rice seed weight: the role of the cytoplasmic ADP-glucose pyrophosphorylase
Plant science (Limerick), Vol.167(6), pp.1323-1333
2004
Handle:
https://hdl.handle.net/2376/108525
Abstract
ADP-glucose pyrophosphorylase (AGPase) controls a rate-limiting step in starch biosynthesis. In cereals, manipulation of this enzyme is a prime target to increase starch production during seed development as a means to increase sink strength and, in turn, crop yields. The
Escherichia coli glgC triple mutant (TM) gene, which encodes a highly active and allosterically insensitive AGPase, was introduced into rice and expressed during endosperm development. The mutated enzyme was targeted to either the amyloplast or cytoplasm to determine the relationship between intracellular location of ADP-glucose formation and starch synthesis. Transgenic rice seeds expressing the amyloplast or cytoplasmic AGPase-TM showed up to 13-fold higher levels of AGPase activity compared to untransformed plants when assayed in the presence of inorganic phosphate to suppress the endogenous activity. Plants having elevated cytoplasmic AGPase activity under Pi-inhibitory conditions showed increases in
14C-sucrose labeling into starch and, in turn, increases (up to 11%) in seed weight over the wt. In contrast, transgenic plants expressing the amyloplast-targeted AGPase activity showed small to moderate increases in
14C-sucrose-labeling rates into starch and either a moderate increase in seed weight or, in several instances, a reduction in seed weight. Our results demonstrate that the intracellular location of AGPase has a marked effect on the capacity of the enzyme to increase starch synthesis and, in turn, seed weight.
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Details
- Title
- Engineering starch biosynthesis for increasing rice seed weight: the role of the cytoplasmic ADP-glucose pyrophosphorylase
- Creators
- Chotipa Sakulsingharoj - Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USASang-Bong Choi - Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USASeon-Kap Hwang - Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USAGerald E Edwards - School of Biological Sciences, Washington State University, Pullman, WA 99164-6340, USAJennifer Bork - Department of Biochemistry, Michigan State University, East Lansing, MI 48824, USAChristopher R Meyer - Department of Biochemistry, Michigan State University, East Lansing, MI 48824, USAJack Preiss - Department of Biochemistry, Michigan State University, East Lansing, MI 48824, USAThomas W Okita - Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA
- Publication Details
- Plant science (Limerick), Vol.167(6), pp.1323-1333
- Academic Unit
- Biological Chemistry, Institute of; Biological Sciences, School of
- Publisher
- Elsevier Ireland Ltd
- Identifiers
- 99900547224101842
- Language
- English
- Resource Type
- Journal article