Sucrose-mediated transcriptional regulation of sucrose symporter activity in the phloem
AUTOR(ES)
Vaughn, Matthew W.
FONTE
National Academy of Sciences
RESUMO
A proton–sucrose symporter mediates the key step in carbon export from leaves of most plants. Sucrose transport activity and steady-state mRNA levels of BvSUT1, a sugar beet leaf sucrose symporter, are negatively regulated specifically by sucrose. Results reported here show that BvSUT1 mRNA was localized to companion cells of the leaf's vascular system, which supports its role in the systemic distribution of photoassimilate. Immunoblot analysis showed that decreased transport activity was caused by a reduction in the abundance of symporter protein. RNA gel blot analysis of the leaf symporter revealed that message levels also declined, and nuclear run-on experiments demonstrated that this was the result of decreased transcription. Further analysis showed that symporter protein and message are both degraded rapidly. Taken together, these data show that phloem loading is regulated by means of sucrose-mediated changes in transcription of a phloem-specific sucrose symporter gene in a regulatory system that may play a pivotal role in balancing photosynthetic activity with resource utilization.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=125066Documentos Relacionados
- Sucrose-mediated translational control
- Phytochrome Mediated Regulation of Sucrose Phosphate Synthase Activity in Maize
- Transcriptional Regulation of Sorghum Defense Determinants against a Phloem-Feeding Aphid1
- His-65 in the proton–sucrose symporter is an essential amino acid whose modification with site-directed mutagenesis increases transport activity
- Circadian Regulation of Sucrose Phosphate Synthase Activity in Tomato by Protein Phosphatase Activity.