The research groups of the Department of Biological and Environmental Sciences of the University of Helsinki and the University of California in San Diego have discovered a gene that is centrally involved in the regulation of carbon dioxide uptake for photosynthesis and water evaporation in plants. The discovery can aid the development of drought-tolerant crops. The article is published online ahead of print in Nature's Advance Online Publication (AOP) on 27 February 2008.
Stomata are tiny pores on the plant leaf surface, through which the leaves absorb carbon dioxide necessary for photosynthesis and release moisture into the air. The plasma membranes of the guard cells that surround the stomatal pore contain several types of ion channels which control the opening and closing of the circular guard cells when the plant encounters a stressful situation, such as increased ozone in the air or drought. The regulation of stomata is an intensively-studied topic and several ion channel types that control their activity have been discovered earlier. However, an anion channel, which is of central importance in the regulation of stomatal activity, was identified only recently by Finnish and American scientist. A measuring device developed at the University of Tartu, Estonia, was of great help in the process.
Professor Jaakko Kangasjärvi and his research group from the University of Helsinki identified the anion channel using a mutation of Arabidopsis thaliana commonly known as thale cress. The mutant does not react by closing its stomata as a response to high ozone or carbon dioxide concentration in the air like a healthy plant does. Scientist at the University of California demonstrated with electrophysiological measurements that the gene identified encodes an anion channel involved in the regulation of stomatal activities.
The gene discovered is of central importance for the mechanisms of stomatal regulation. Unlike the ion channels detected previously, this newly discovered anion channel takes part in the regulation of all the main stomatal activities.
Climate change makes it all the more important to know about the mechanisms involved in stomata regulation. Aridity is on the increase across the globe, as is the world population. Increasingly dry areas should be taken into cultivation to ensure food production. When developing crops that thrive in dry areas, it is important to know well the mechanisms that regulate stomata, through which plants evaporate moisture.
The effects of climate change, which increases atmospheric ozone and carbon dioxide concentrations, cause another challenge for plants. Plants protect themselves against high ozone by closing the stomata on their leaves. While this protection mechanism minimises damage to the plant, it also reduces carbon dioxide uptake for photosynthesis and thus could reduce the sequestering of the excess atmospheric carbon in plant material. A different kind of plant, however, could grow better in the new conditions. This research will provide a new tool for geneticists in the development of drought-resistant plants.