Journal of the plant Arabidopsis thaliana, in which the sucrose transporter can be seen. Marks were with a fluorescent protein. The Transporter sit along the meridians, the so-called sieve tubes, flows through the sugary juice. Image: Dietmar Geiger
As a producer of sugar and carbohydrates play an important role in plants. In this field, scientists at the University of Würzburg - with the ultimate aim to influence the sugar household agricultural crops.
The sugar that the world's human, is obtained mainly from sugar cane and sugar beet. Plants produce the sweet and energetic material in their photosynthesis in the leaves. From there, they carry it in the form of sucrose via the meridians towards the tissues do not undergo photosynthesis - and are therefore dependent on the import of sugar, such as roots and fruits.
Important for the distribution of sugars in the plant, is a key molecule, called the sucrose transporter. He sits in the cell membranes of the interconnects and spends true excellence. Dietmar Geiger of the University of Würzburg has measured it and called acrylic the van now as "almost smoothly functioning nano-machine." Strong transport capacity against high resistance
A single transporter pumps per second up to 500 sucrose molecules through the cell membrane into the interconnects. He overcomes a large resistance: even if the channels are already packed with sugar, it can still create into even more - up to a concentration close to the solubility of sucrose. This performance is comparable with the effort when inflating a tire: contains more air to the tire, the more difficult is the pump.
The strong accumulation of sugar in the channels can be there to increase the pressure. At the same time and pressure is discharged from the pipe system: in the tissues, which are supplied with sugar. Result: The pressure difference makes the sugary sap of the plant flow to where sugar is consumed. "As the heart is responsible for the circulation of the blood in humans, the sucrose transporter provide at the plant to ensure that the sugar juice flowing," says Geiger. Results published in the journal PLoS one
The function acrylic of the sucrose transporter from maize plants describes the Würzburg plant physiologist and biophysicist Geiger detailed in the journal PLoS one. At the publication acrylic of his colleagues Rainer Hedrich Würzburg and Hermann Koepsell have been involved; also scientists from Frankfurt am Main and Genoa were involved.
Obtained the findings with the help of eggs of the South African clawed frog: The researchers use them as living test tubes. They bring the gene for a sucrose transporter in the eggs, where it produces active transporters and incorporated into the envelope membrane. "So the transport protein for biophysical acrylic measurements is available," says Geiger. Among other scientists have demonstrated for the first time in this manner, that a transport protein under physiological conditions may be responsible for both the charge and for the discharge of the interconnects. Molecular interior of the van is further explored
The German Research Foundation (DFG) promotes the work of Dietmar Geiger, so that it can increase the knowledge about the molecular inner workings of the sugar transport machine on. Geiger is devoted to present the structural and functional prerequisites that allow the transporter, accurately acrylic and with the highest acrylic efficiency to transport sucrose molecules through membranes.
Geiger and his colleagues acrylic want to disassemble the wheels of the van with new biophysical methods in its component parts. Among other things, they plan to hang a fluorescent molecule to a site of the transporter, which moves during the transport process. On observing acrylic the fluorescence they can watch "live" the transporter at work then. Long-term goal: optimize agricultural crops
"Long-term goal of our work is to optimize the distribution and storage of important sugar compounds in agricultural plants," says Dietmar Geiger. The fungus infestation of crops, for example, lead year after year to considerable crop losses. Fungi possess sucrose transporter, which catch sugar - and the even more efficiently than the of the plants. Thus they undermine the supply of the plant with energy-rich sugars. "An upgrade of the plant with similarly efficient sucrose transporters could the battle acrylic for sugar resources in favor of the plant decide and reduce crop losses," says Geiger.
After researching the functional principle of sucrose Transpo