Stanford, CA Scientists at Carnegie's Department of Plant Biology have made the first real-time observations of sugars in the cells of intact and living plant tissues. With the help of groundbreaking imaging techniques, the group has determined that plants maintain extremely low levels of sugar in their roots--as much as 100,000 times lower than previous estimates. The new technology will enable new studies of sugar metabolism in plants, which will inform the effort to engineer higher crop yields for food and biofuel production.
Led by Carnegie staff member Wolf Frommer, the researchers designed genetically-encoded fluorescent tags to monitor glucose, an important sugar, in leaf and root tissues of the model plant Arabidopsis thaliana. The technique has allowed the researchers to track glucose over time and space at unprecedented detail, in living and undisturbed plant tissues. The work appears in the September issue of the journal Plant Cell. The group has also developed a FRET sensor for sucrose, a major transport sugar in plants. This work will appear in the September issue of the Journal of Biological Chemistry.
"Until now, we have had few clues regarding how much sugar is in an individual cell in a multicellular plant," Frommer said. "We normally grind up a leaf or a root and average the information for all cells, but if sugar levels rise in one cell and drop in another, we would see no change in this average." Also, because the cell can distribute sugar among subcellular organelles, it is nearly impossible to know how much sugar is in any cell compartment at a given time.
"Time resolution is another problem," Frommer added. "We can sample tissue at intervals, but if the sugar changes in waves, we might miss the right time point. Our new technology addresses all of these problems by measuring sugar flux in real time in individual cells, with subcellular resolution."