The pores, which are responsible for the gas exchange of plants, can become water-saving through genetic changes.
Reading aloud Scientists have discovered how to make plants fit for a future with a higher carbon dioxide level in the air: when certain sensor proteins in the leaves are optimized, plants react more sensitively to CO2. As a result, they do not have to open the tiny breathing holes in their leaves quite so far? with the result that less water evaporates at the same time. Especially in arid areas such modified plants could bring many benefits, the researchers believe. However, for the plants, the water-saving mode is associated with a problem: much like a person who suddenly sweats less, they can not lower their temperature so effectively anymore? and that can be a problem in very hot areas. The team around Julian Schroeder of the University of California in San Francisco reports about their discovery. Through microscopic stomata formed by two elongated cells on the leaf surface, the gas exchange of the plant takes place. There, plants absorb carbon dioxide and release oxygen. However, as a side effect, the plant loses hundreds of water molecules to pick up a single carbon dioxide molecule. With an increased concentration of carbon dioxide, however, these openings close something? enough CO2 can still be absorbed and water loss decreases at the same time. The researchers around Schroeder have now found that a particular enzyme, a carbonic anhydrase, acts as a kind of gatekeeper and triggers this closure depending on the carbon dioxide concentration. Carbonic anhydrases are biocatalysts that also play a role in photosynthesis.

However, the gatekeepers react rather sluggishly in many plants. The result is an unnecessary loss of water, which can lead to high additional costs in agriculture. To test whether it is possible to increase the efficiency of the closing enzymes, Schroeder and his colleagues modified the genome of the Arabidopsis thaliana field, a plant that is very popular with geneticists. Specimens without functioning carbonic anhydrase genes do not respond at all to a CO2 increase, the researchers were able to show. However, if they are equipped with an above-average number of copies of the genes, their sensitivity increases significantly: as a result, they lost 44 percent less water than their genetically unchanged counterparts. The photosynthesis was not affected by the sensitization of the plant.

In dry areas it is advantageous to grow water-saving plants, explain the researchers. For example, in the US state of California, irrigation of crops currently requires 79 percent of the total water coming from redirected rivers and pumping up groundwater. However, one must be careful and take into account the greater risk of overheating, the scientists point out.

Julian Schroeder (University of California, San Francisco) et al .: Nature Cell Biology, doi: 10.1038 / ncb2009 ddp / Jessica von Ahn ad


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