Has Arabidopsis SWEETIE protein a role in sugar flux and utilization?

In plants, sugars affect growth and development and play an important role in the intricate machinery of signal transduction. Understanding the mechanisms behind the flux of sugar in the plant is of central interest. We recently characterized an Arabidopsis mutant: sweetie, which is defective in the control of growth and development, sterile, shows premature senescence and affects sugar metabolism. Our microarray analysis showed that 15 genes annotated as sugar transporter related proteins were found to be upregulated in sweetie while one sugar transporter gene was found to be downregulated. Most of them are unspecified sugar transporters but four genes have been annotated as monosaccharide transporters and one has been annotated as a disaccharide transporter. Moreover, as computer analyses predicted that SWEETIE might be a membrane protein and might have a function of glycosyl transferase, our data suggest that SWEETIE could be involved in the general control of sugar flux and modulates many important processes such as morphogenesis, flowering, stress responses and senescence.