Cytosolic Phosphorylating Glyceraldehyde-3-Phosphate Dehydrogenases
Affect Arabidopsis Cellular Metabolism and Promote Seed Oil
Accumulation |
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Authors: | Liang Guo Fangfang Ma Fang Wei Brian Fanella Doug K Allen Xuemin Wang |
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Institution: | aDepartment of Biology, University of Missouri, St. Louis, Missouri 63121;bDonald Danforth Plant Science Center, St. Louis, Missouri 63132;cU.S. Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, St. Louis, Missouri 63132 |
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Abstract: | The cytosolic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPC) catalyzes a key
reaction in glycolysis, but its contribution to plant metabolism and growth are not
well defined. Here, we show that two cytosolic GAPCs play important roles in cellular
metabolism and seed oil accumulation. Knockout or overexpression of
GAPCs caused significant changes in the level of intermediates in
the glycolytic pathway and the ratios of ATP/ADP and NAD(P)H/NAD(P). Two double
knockout seeds had ∼3% of dry weight decrease in oil content compared with
that of the wild type. In transgenic seeds under the constitutive 35S promoter, oil
content was increased up to 42% of dry weight compared with 36% in the wild type and
the fatty acid composition was altered; however, these transgenic lines exhibited
decreased fertility. Seed-specific overexpression lines had >3% increase in seed
oil without compromised seed yield or fecundity. The results demonstrate that
GAPC levels play important roles in the overall cellular
production of reductants, energy, and carbohydrate metabolites and that
GAPC levels are directly correlated with seed oil accumulation.
Changes in cellular metabolites and cofactor levels highlight the complexity and
tolerance of Arabidopsis thaliana cells to the metabolic
perturbation. Further implications for metabolic engineering of seed oil production
are discussed. |
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