Sucrose-mediated transcriptional regulation of sucrose symporter activity in the phloem

摘要

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 company- ion 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 redu- ction in the abundance of symporter protein.