Background: Plants exchange carbon dioxide and water through stomatal pores located in the epidermis of leaves and stems. Carbon dioxide is taken up for photosynthesis and water is lost through transpiration through the stomatal pore. The stomatal pore is made up of specialized cells called guard cells that balance the plants need for carbon dioxide uptake and water loss by opening and closing of the pores in response to environmental conditions. Stomata open in response to low levels of carbon dioxide and will close when the levels are high. Knowledge of how atmospheric CO2 is perceived by the guard cells could be used to manipulate plant CO2 responses so that the carbon and water use efficiency during plant growth could be optimized. Technology Description: UC San Diego investigators have identified the OST1 (Open Stomata 1) SnRK2.2 or SnRK2.3 protein kinases as major regulators of carbon dioxide-induced stomatal pore opening or closing. Expression of these genes from a guard cell-specific promoter can increase the water use efficiency enhance CO2 sensitivity or increase the rate of growth or biomass production of a plant. Control of expression levels of carbonic anhydrases together with OST1 or related protein kinases using guard cell-targeted expression could allow engineering of water transpiration and water use efficiency in plants. Guard cell specific overexpression or suppression of these kinases can be a useful approach to control CO2 influx for photosynthesis and regulation of stomatal movements and for improved water use efficiency in plants. Applications: Manipulating how plants sense carbon dioxide using OST1 may aid in the production of crops with altered and improved gas exchange and water use efficiency. This approach may also improve plant growth of various plant species at a higher atmospheric carbon dioxide concentration. This is critically important in light of increasing atmospheric carbon dioxide levels and limited fresh water supplies.
1) Improving water-use efficiency for crops 2) Creating drought resistant crops 3) Optimizing plant growth in higher CO2 conditions 4) biomass accumulation/biofuel production