Gene that controls ozone resistance of plants could lead to drought-resis...(at the gene responsible for the mutation...)

Date:2/27/2008

at the gene responsible for the mutation is essential for the function of what they called a slow or S-type anion channel. Anions are negatively charged ions and these particular anion channels are located within specialized cells called guard cells that surround the stomatal pores. The gene was therefore named SLAC1 for slow anion channel 1.

Guard cells close stomatal pores in the event of excess ozone or drought. When this gene is absent or defective, the mutant plant fails to close its stomatal pores.

In 1989, Schroeder discovered these slow anion channels in guard cells by electrical recordings from guard cells using tiny micro-electrodes. He predicted that these anion channels would be important for closing the stomatal breathing pores in leaves under drought stress.

The model we proposed back then was that the anion channels are a kind of electrical tire valve in guard cells, because our studies suggested that closing stomatal pores requires a type of electrically controlled deflation of the guard cells, he said. But finding the gene responsible for the anion channels has eluded many researchers since then.

The latest study shows that the SLAC1 gene encodes a membrane protein that is essential for the function of these anion channels. We analyzed a lot of mechanisms in the guard cells and, in the end, the slow anion channels were what was missing in the mutant, said Yongfei Wang, a post doctoral associate in Schroeders lab and co-first author of the paper.

The scientists showed that the SLAC1 gene is required for stomatal closing to various stresses, including ozone and the plant hormone abscisic acid, which controls stomatal closing in response to drought stress. Elevated carbon dioxide in the atmosphere also causes a partial closing of stomatal pores in leaves. By contrast, the scientists found, the mutant gene does not close the plants stomatal pores when carbon dioxide levels are elevated.

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Contact: Kim McDonald kmcdonald@ucsd.edu 858-534-7572 University of California - San Diego Source:Eurekalert

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