Agricultural water use accounts for 90 percent of global freshwater—yet production still needs to dramatically increase to feed this century’s growing population. For the first time, scientists have improved how a crop uses water by 25 percent without compromising yield by altering the expression of one gene that is found in all plants, as reported in Nature Communications.
The research is part of the international research project Realizing Increased Photosynthetic Efficiency (RIPE) that is supported by Bill & Melinda Gates Foundation, the Foundation for Food & Agriculture Research and the U.K. Department for International Development.
“This is a major breakthrough,” said RIPE Director Stephen Long, Ph.D., Ikenberry Endowed Chair of Plant Biology and Crop Sciences at University of Illinois. “Crop yields have steadily improved over the past 60 years, but the amount of water required to produce one ton of grain remains unchanged—which led most to assume that this factor could not change. Proving that our theory works in practice should open the door to much more research and development to achieve this all-important goal for the future.”
The international team increased the levels of a photosynthetic protein (PsbS) to conserve water by tricking plants into partially closing their stomata, the microscopic pores in the leaf that allow water to escape. Stomata are the gatekeepers to plants: When open, carbon dioxide enters the plant to fuel photosynthesis, but water is allowed to escape through the process of transpiration.
The team improved the plant’s water-use-efficiency—the ratio of carbon dioxide entering the plant to water escaping—by 25 percent without significantly sacrificing photosynthesis or yield in real-world field trials
Four factors can trigger stomata to open and close: humidity, carbon dioxide levels in the plant, the quality of light and the quantity of light. This study is the first report of hacking stomatal responses to the quantity of light.
This research complements previous work, published in Science, which showed that increasing PsbS and two other proteins can improve photosynthesis and increase productivity by as much as 20 percent. Now the team plans to combine the gains from these two studies to improve production and water-use by balancing the expression of these three proteins.
The research team will now apply their discoveries to improve the water-use-efficiency of food crops and test their efficacy in water-limited conditions.
RIPE is led by the University of Illinois in partnership with the University of Essex, Lancaster University, Australian National University, Chinese Academy of Sciences, Commonwealth Scientific and Industrial Research Organisation, University of California, Berkeley and Louisiana State University and USDA-ARS.
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