Sonnewald U (2005)
Publication Status: Published
Publication Type: Journal article
Publication year: 2005
Publisher: SPRINGER
Book Volume: 221
Pages Range: 479-492
Journal Issue: 4
DOI: 10.1007/s00425-004-1458-4
The aim of this work was to examine the role of sucrose-6-phosphate phosphatase (SPP; EC 3.1.3.24) in photosynthetic carbon partitioning. SPP catalyzes the final step in the pathway of sucrose synthesis; however, until now the importance of this enzyme in plants has not been studied by reversed-genetics approaches. With the intention of conducting such a study, transgenic tobacco plants with reduced SPP levels were produced using an RNA interference (RNAi) strategy. Transformants with less than 10% of wild-type SPP activity displayed a range of phenotypes, including those that showed inhibition of photosynthesis, chlorosis, and reduced growth rates. These plants had strongly reduced levels of sucrose and hexoses but contained 3-5 times more starch than the control specimens. The leaves were unable to export transient starch during extended periods of darkness and as consequence showed a starch- and maltose-excess phenotype. This indicates that no alternative mechanism for carbon export was activated. Inhibition of SPP resulted in an approximately 1,000-fold higher accumulation of sucrose-6-phosphate (Suc6P) compared to wildtype leaves, whereas the content of hexose-phosphates was reduced. Although the massive accumulation of Suc6P in the cytosol of transgenic leaves was assumed to impair phosphate-recycling into the chloroplast, no obvious signs of phosphate-limitation of photosynthesis became apparent. 3-Phosphoglycerate (3-PGA) levels dropped slightly and the ATP/ADP ratio was not reduced in the transgenic lines under investigation. It is proposed that in SPP-deficient plants, long-term compensatory responses give rise to the observed acceleration of starch synthesis, increase in total cellular Pi content, decrease in protein content, and related reduction in photosynthetic activity.
APA:
Sonnewald, U. (2005). Decreased sucrose-6-phosphate phosphatase level in transgenic tobacco inhibits photosynthesis, alters carbohydrate partitioning, and reduces growth. Planta, 221(4), 479-492. https://doi.org/10.1007/s00425-004-1458-4
MLA:
Sonnewald, Uwe. "Decreased sucrose-6-phosphate phosphatase level in transgenic tobacco inhibits photosynthesis, alters carbohydrate partitioning, and reduces growth." Planta 221.4 (2005): 479-492.
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